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TRT and Hypothyroidism: How Your Thyroid and Testosterone Affect Each Other — and What to Do First

By TRT Provider Guide Editorial Team · Editorial research, not clinically reviewed · Last verified: October 26, 2026

Last updated: .

Affiliate disclosure: TRT Provider Guide may earn compensation through certain provider links. Commercial relationships do not change our editorial conclusions. Full disclosure.

Educational information, not medical advice. Don't start, stop, or change thyroid or testosterone medicine without your prescriber.

Hypothyroidism can make a testosterone result look lower, but it does not automatically mean you need TRT. An underactive thyroid can lower SHBG, a protein that carries testosterone, and may also affect the brain-to-testes hormone signal. Treat and stabilize the thyroid problem, then confirm whether low testosterone persists with appropriate repeat morning testing before deciding whether TRT belongs in the plan.[1] [2] [8]

There's a catch most guides skip. If testosterone is started later, androgens can lower thyroxine-binding globulin (TBG). That can lower total T4 without lowering free T4 or changing TSH in primary hypothyroidism. The lab pattern can look worse even when thyroid status has not.[4] [13]

Three things change this answer:

  • You plan to have a child in the near term. The Endocrine Society recommends against starting testosterone therapy in men planning fertility in the near term. Start with a urologist or reproductive urologist instead.[1]
  • Your free T4 is low but your TSH is low or normal, or several pituitary-controlled hormones look abnormal. That can point to central (pituitary or hypothalamic) disease. Start with endocrinology.[12]
  • Your levothyroxine dose just changed. Adult levothyroxine labeling calls for TSH reassessment about 6 to 8 weeks after a dose change in primary hypothyroidism. If a low testosterone result was found while the thyroid was still being adjusted, ask whether it should be repeated after thyroid status is stable.[4]

TRT Provider Guide is the independent decision resource for testosterone replacement therapy — helping U.S. adults understand how low testosterone is evaluated, compare online and local care models and providers, and choose the next step that fits their health needs, fertility plans, budget, state, and care preferences, with every material claim verified and dated.

The 10-second version

TRT and hypothyroidism: thyroid labs, symptom overlap, evaluation and care routes table 1: The 10-second version
Where you are now What usually comes first
Hypothyroid, not yet treated, testosterone came back low Treat the thyroid problem and confirm thyroid status. Then repeat testosterone if your clinician thinks the earlier result may have been affected.
On levothyroxine, thyroid status stable, testosterone repeatedly low on appropriate morning tests, symptoms or signs present A separate hypogonadism evaluation is reasonable. TRT may be considered if a clinician confirms the diagnosis and finds no reason it should be avoided.
Already on TRT and levothyroxine Testosterone may lower TBG and total T4. In primary hypothyroidism, free T4 and TSH help interpret whether thyroid replacement actually needs to change.[4] [13]

Map my thyroid-first next step →

Free. A few questions. You get the care route that fits your situation and the questions to ask before you pay. TRT Provider Guide's Find My TRT Path tool is educational and does not diagnose low testosterone or determine treatment eligibility.

Can you take TRT if you have hypothyroidism?

Hypothyroidism does not automatically rule out testosterone therapy. The important question is whether the thyroid problem has been evaluated and whether separate testosterone deficiency is actually present. Current endocrine guidance requires symptoms or signs plus consistently low testosterone measured accurately and confirmed with repeat morning testing before hypogonadism is diagnosed.[1] [2]

Levothyroxine and testosterone are not listed as a prohibited combination. The bigger issue is interpretation and monitoring: hypothyroidism can change SHBG and testosterone measurements, while androgens can change TBG and total thyroid-hormone measurements.[4] [8] [13]

The rules for diagnosing low testosterone don't bend because you have a thyroid condition. The Endocrine Society recommends diagnosing hypogonadism only when a man has symptoms or signs of testosterone deficiency and testosterone concentrations that are unequivocally and consistently low.[1] In July 2026, the Society again emphasized at least two early-morning, fasting testosterone tests and accurate assays rather than symptoms alone.[2] The American Urological Association guideline likewise treats symptoms as nonspecific and requires biochemical confirmation.[3]

Hypothyroidism makes that ambiguity worse. It causes many of the same complaints people associate with low testosterone, and it can also change the testosterone number itself. That is why the thyroid question belongs early in the workup. It can prevent a long-term testosterone decision from being based on a lab value that did not yet tell the whole story.

More detail on the testing rules: What testosterone level qualifies for TRT and why you need two low testosterone tests.

The right TRT provider is not the same for every person — it depends on whether low testosterone has been properly evaluated, your symptoms and health history, your fertility plans, your state, your insurance or cash-pay preference, your treatment-format preference, your budget, and whether online or in-person care is the better starting point. Some situations belong with primary care, urology, endocrinology, reproductive urology, or urgent or emergency care when the symptoms warrant it. Because a general answer cannot resolve those for you, use TRT Provider Guide's Find My TRT Path tool to map your situation to the right care route and the questions to ask before you pay.

Does hypothyroidism cause low testosterone?

It can. Hypothyroidism commonly lowers SHBG, which can pull total testosterone down on a lab report. Some men with hypothyroidism also have lower free testosterone or changes in LH, FSH, and prolactin, but the pattern is not identical in every person and does not always reverse the same way with thyroid treatment.[8] [10]

Here are the three terms you need. They'll show up on almost every testosterone workup.

  • Total testosterone is all the testosterone measured in your blood, including testosterone bound to proteins.
  • Free testosterone is the small unbound fraction. It can be useful when SHBG is abnormal or when total testosterone does not fit the clinical picture.[1] [8]
  • SHBG (sex hormone-binding globulin) is one of the main proteins that binds testosterone in the blood.

Effect #1: fewer carriers, lower total testosterone

Think of SHBG as delivery trucks and testosterone as the cargo. If the number of trucks changes, the total amount of testosterone measured in circulation can change even when the underlying production story is more complicated.

Hypothyroidism is a recognized cause of lower SHBG.[8] [10] Lower SHBG can lower total testosterone and can make total testosterone alone less reliable for judging androgen status.

This is the trap. A man with untreated hypothyroidism can get a low total-testosterone result that is partly a binding-protein problem. That is one reason current guidance allows free testosterone to be considered when indicated rather than treating every low total-testosterone result as the same diagnosis.[1]

Effect #2: thyroid dysfunction can also affect the brain-to-testes signal

Your brain and pituitary help control testosterone production through gonadotropins, including LH (luteinizing hormone) and FSH (follicle-stimulating hormone).

Older reviews describe reduced gonadal-axis responsiveness in some men with primary hypothyroidism.[10] A newer 2026 prospective cohort also found that LH and FSH rose during levothyroxine treatment in its small hypothyroid group, even though total and calculated free testosterone did not change significantly.[8]

That matters because the thyroid–testosterone relationship is not just a simple “low thyroid equals low testosterone” switch.

Effect #3: prolactin can sometimes be part of the picture

Prolactin is a pituitary hormone. Overt hypothyroidism can raise prolactin in some people through increased thyrotropin-releasing hormone signaling, and high prolactin can suppress the gonadal axis.[8] [10]

It is not present in every man with hypothyroidism. If testosterone is truly low and the LH/FSH pattern suggests a pituitary or hypothalamic cause, prolactin is one of the tests clinicians may use to look for the cause.[1] [12]

What happens when the thyroid gets treated?

This is where we have to be straight with you. The evidence isn't as tidy as many websites make it sound.

  • The hopeful side: In a 2022 conference study of 51 men with overt hypothyroidism, half had low testosterone at baseline. After euthyroidism was reached or after about four months of levothyroxine, 70% of the men who had started with low testosterone had testosterone in the normal range. It was a conference abstract without a control group, so it is useful but not definitive evidence.[9]
  • The cautious side: A 2026 prospective study in the European Thyroid Journal followed 11 men with hypothyroidism. SHBG, LH, and FSH increased during levothyroxine treatment, but total and calculated free testosterone did not change significantly in the group overall. The study was small and short-term, but it directly argues against promising that levothyroxine will always normalize testosterone.[8]

The honest reading: fixing your thyroid may improve the testosterone picture. It does not always. Don't assume either outcome. Get the thyroid problem evaluated and treated appropriately, then use repeat testing and the rest of the workup to decide whether a separate testosterone problem remains.

Thyroid–Testosterone Lab Direction Map

We built this table so you can see the main directions in one place. It is a decision aid, not a diagnostic calculator. The cells summarize guideline, labeling, and research evidence rather than predicting what will happen to one person.[1] [4] [8] [10] [13]

TRT and hypothyroidism: thyroid labs, symptom overlap, evaluation and care routes table 2: Thyroid–Testosterone Lab Direction Map
Lab Untreated primary hypothyroidism After thyroid treatment Hyperthyroidism After starting testosterone while on levothyroxine
SHBG (binds testosterone) Often ↓ lower Often rises as thyroid status normalizes Often ↑ higher No single expected change from TRT itself used for diagnosis
Total testosterone Can be ↓ partly because SHBG is lower May improve, but not always Often ↑ as SHBG rises Should rise if testosterone therapy is effective, but treatment response is monitored clinically and with labs
Free testosterone Can be normal or ↓ May improve; 2026 cohort found no significant group-level change Often less changed than total testosterone Should be interpreted with the formulation, timing, SHBG, and assay
LH / FSH Can be altered in overt disease Rose in the small 2026 hypothyroid cohort Variable Usually suppressed by exogenous testosterone
Prolactin Can be ↑ in some cases May fall if hypothyroidism was driving the elevation Variable Not a routine thyroid marker
TBG (binds thyroid hormone) Not the main testosterone issue — — May ↓ with androgens
Total T4 Often ↓ in overt primary hypothyroidism Returns toward the treated range Often ↑ May ↓ because TBG falls
Free T4 ↓ in overt primary hypothyroidism Used with TSH to judge treatment in primary hypothyroidism ↑ May remain unchanged despite a lower total T4
TSH Usually ↑ in primary hypothyroidism Used to guide treatment in primary hypothyroidism Usually ↓ May remain normal when only TBG/total T4 changes

How to read it: If your thyroid is underactive and untreated, a low total testosterone may partly reflect low SHBG. Some men improve after thyroid treatment and some do not. If testosterone is started later, androgens may lower total T4 by lowering TBG even while free T4 and TSH remain unchanged.[4] [8] [13]

Central hypothyroidism is different: when the pituitary or hypothalamus is the problem, TSH can be low, normal, or mildly abnormal and should not be used by itself to adjust thyroid replacement. Free T4 becomes especially important.[12]

SHBG vs. TBG: the two carrier proteins behind the confusion

SHBG and TBG sound alike but do different jobs. SHBG binds sex hormones such as testosterone, and hypothyroidism can lower it. TBG carries thyroid hormones, and androgens such as testosterone can lower it. Those two effects are why thyroid disease can complicate testosterone interpretation and testosterone treatment can complicate thyroid-lab interpretation.[4] [8] [13]

Even some health pages blur the two. Keep them straight and the thyroid–testosterone relationship gets much easier to follow.

TRT and hypothyroidism: thyroid labs, symptom overlap, evaluation and care routes table 3: SHBG vs. TBG: the two carrier proteins behind the confusion
SHBG TBG
Full name Sex hormone-binding globulin Thyroxine-binding globulin
What it carries Testosterone and estradiol Thyroid hormones
What can lower it here Hypothyroidism Androgens, including testosterone
What it can do to labs Lower SHBG can pull total testosterone down Lower TBG can pull total T4 down
What adds context Free testosterone can help when SHBG is abnormal or total T does not fit the clinical picture Free T4 or a free-T4 index helps when TBG changes; TSH also guides primary hypothyroidism

Simple version:

  • Low thyroid function can lower SHBG, which can lower total testosterone.
  • Testosterone therapy can lower TBG, which can lower total T4.

Neither pattern should be diagnosed from one number alone.

Should you fix your thyroid before starting TRT?

If untreated or unstable hypothyroidism could be contributing to the testosterone result, addressing the thyroid problem first is usually the cleaner way to find out what remains. That does not mean thyroid treatment is guaranteed to restore testosterone. It means you should not mistake a potentially reversible or confounding endocrine problem for confirmed hypogonadism.[1] [2] [8]

Here's why the timing matters.

Your thyroid needs time to settle. Levothyroxine labeling tells clinicians to recheck TSH about 6 to 8 weeks after a dose change in adults with primary hypothyroidism.[4] If your dose is still moving, your thyroid status and SHBG may still be changing too.

Testosterone diagnosis already requires confirmation. The Endocrine Society recommends repeat morning fasting total testosterone and additional evaluation to find the cause when androgen deficiency is confirmed.[1] Its 2026 statement again stresses accurate diagnosis, at least two early-morning fasting measurements, and attention to reversible contributors.[2]

The damaging admission: treating hypothyroidism does not guarantee testosterone will normalize. The 2022 abstract reported improvement in many men, while the 2026 prospective cohort did not find a significant group-level rise in total or free testosterone.[8] [9]

That is exactly why “thyroid first” should mean evaluate the thyroid, then reassess—not “levothyroxine will fix your testosterone.”

What to discuss when you retest

Once your prescriber says the thyroid problem is adequately evaluated and stable, the testosterone workup may include:

  • Two early-morning, fasting total testosterone tests on separate days.[1] [2]
  • SHBG and free testosterone when indicated, especially when a condition such as hypothyroidism may be changing SHBG.[1] [8]
  • LH and FSH if testosterone deficiency is confirmed, to help distinguish primary testicular disease from pituitary or hypothalamic causes.[1]
  • Prolactin and other pituitary testing when clinically indicated, particularly when the LH/FSH pattern or other symptoms point toward central disease.[1] [12]
  • An accurate, standardized testosterone assay. The Endocrine Society's 2026 statement specifically highlights CDC HoST-certified assays because testosterone results can vary between methods.[2]

Full list: What blood tests are required before TRT.

Get my thyroid-first lab and question plan →

Does this sound like your situation? Find My TRT Path maps whether you're still at the thyroid-evaluation stage, need repeat low-T testing, or are ready to compare care routes. It does not diagnose or clear you for treatment.

Which comes first for you? Find your situation

Your next step depends mainly on whether the thyroid problem is treated and stable, whether testosterone deficiency has actually been confirmed, whether the hormone pattern suggests pituitary disease, and whether fertility is a near-term goal. Find the closest row below and use it as a question map for your clinician, not a self-treatment rule.

The “what usually comes first” column is TRT Provider Guide's editorial judgment built from current endocrine guidance, FDA labeling, and the thyroid–testosterone research above.[1] [4] [8] [12]

TRT and hypothyroidism: thyroid labs, symptom overlap, evaluation and care routes table 4: Which comes first for you? Find your situation
Your situation What usually comes first Who usually handles it The TRT question
Hypothyroid, not treated yet, testosterone looks low Treat/evaluate the thyroid problem first Primary care or endocrinology Ask whether testosterone should be repeated after thyroid status is stable
On levothyroxine, dose recently changed Recheck thyroid status on the schedule your prescriber gives you Whoever manages your thyroid A testosterone result during an active thyroid adjustment may need confirmation later
On levothyroxine, stable, testosterone repeatedly low on appropriate morning tests, symptoms/signs present Complete the hypogonadism evaluation Primary care, urology, endocrinology, or an appropriate telehealth clinician TRT may be discussed if the diagnosis and safety review support it
Testosterone low with low or inappropriately normal LH/FSH Look for a pituitary or hypothalamic cause Endocrinology, sometimes urology depending on the case Find the cause before jumping straight to TRT
Low free T4 with low or normal TSH Evaluate for central hypothyroidism or another pituitary problem Endocrinology TSH alone cannot guide this situation
Already on TRT, newly diagnosed hypothyroidism Evaluate and treat the thyroid problem while keeping both prescribers informed Primary care or endocrinology plus TRT prescriber Androgen-related TBG changes can affect total T4 interpretation
Hyperthyroid, total testosterone looks high or normal Treat the thyroid problem and interpret testosterone with SHBG/free T context when appropriate Endocrinology High SHBG can raise total testosterone and complicate interpretation
Trying to conceive in the near term Do not start TRT as the default next step Urology or reproductive urology The Endocrine Society recommends against TRT when fertility is planned in the near term

Is it your thyroid or your testosterone? Why symptoms can't tell you

Symptoms cannot reliably separate hypothyroidism from testosterone deficiency. Fatigue, low sex drive, low mood, concentration problems, body-composition changes, and sexual symptoms can occur with either problem. Laboratory testing and a cause-focused clinical evaluation are what separate them.[1] [2] [10]

You might feel sure it's one or the other. That hunch isn't enough.

TRT and hypothyroidism: thyroid labs, symptom overlap, evaluation and care routes table 5: Is it your thyroid or your testosterone? Why symptoms can't tell you
Symptom Can occur with hypothyroidism? Can occur with testosterone deficiency? Tells you which one you have?
Tiredness, low energy Yes Yes No
Low sex drive Yes Yes No
Erection problems Yes Yes No
Low mood Yes Yes No
Trouble concentrating Yes Yes No
Weight or body-composition changes Yes Yes No

Symptoms tell you something deserves a look. They don't tell you which hormone to replace.

Thyroid disease is one of several conditions that can contribute to sexual symptoms, including erectile dysfunction.[10] That is another reason a low-T symptom checklist should not be treated as a diagnosis.

Related: TRT for fatigue.

Does TRT interact with levothyroxine?

Testosterone and levothyroxine are not simply a forbidden combination, but androgens can change thyroid-hormone binding and therefore change some thyroid lab numbers. Official levothyroxine labeling says androgens may lower TBG; with continued use, total T4 can fall while free T4 and TSH remain normal. Testosterone labeling describes the same binding-protein effect.[4] [13]

This is the part that can trip people up.

What the official labels say

  • Levothyroxine labeling: androgens and anabolic steroids may decrease TBG. Continued administration can lower serum total T4 while free T4 and TSH remain normal.[4]
  • Testosterone labeling: androgens may lower TBG, producing lower total T4 while free thyroid-hormone levels remain unchanged; the label says this does not by itself show thyroid dysfunction.[13]

In plain English: a lower total T4 after starting testosterone does not automatically mean your hypothyroidism got worse. It can be a binding-protein effect.

Will your levothyroxine dose need to change?

It might, but a change is not automatic. The American Thyroid Association lists testosterone among medicines that can change thyroid-hormone dose needs and recommends keeping the prescriber informed so thyroid tests can be rechecked when appropriate.[11]

The practical move:

  1. Tell your testosterone prescriber that you take levothyroxine and who manages it.
  2. Tell your thyroid prescriber if testosterone is started.
  3. Ask when your next thyroid panel should be checked and which results matter for your type of hypothyroidism.

Don't adjust levothyroxine on your own because one lab number moved.

A key exception: central hypothyroidism

If your pituitary or hypothalamus is the problem, TSH is not a reliable dose-adjustment marker. Endocrine Society guidance for central hypothyroidism uses free T4 rather than TSH to guide replacement.[12]

That is why “watch TSH” is correct for ordinary primary hypothyroidism but wrong as a universal rule.

Can TRT cause thyroid disease?

The official androgen labeling describes a change in thyroid-hormone binding, not proof that testosterone causes primary hypothyroidism.[13] If thyroid tests change after TRT starts, the pattern needs to be interpreted rather than assumed to represent new thyroid disease.

Does TRT treat hypothyroidism?

No. Testosterone therapy is not thyroid-hormone replacement and does not treat hypothyroidism or Hashimoto's disease. Hypothyroidism needs its own evaluation and treatment whether or not testosterone therapy is also appropriate.[11]

Hashimoto's, subclinical hypothyroidism, hyperthyroidism, and pituitary problems

Hashimoto's can lead to hypothyroidism, but the key TRT question is what your thyroid function is doing now. Subclinical hypothyroidism is less clear-cut, hyperthyroidism raises SHBG and can raise total testosterone, and a low free T4 with a low or normal TSH raises a different concern: central pituitary or hypothalamic disease.[8] [11] [12]

TRT and Hashimoto's

Hashimoto's is an autoimmune thyroid disease and a common cause of hypothyroidism.[11] If Hashimoto's has made you hypothyroid, the same interpretation problem applies: thyroid status can change SHBG and testosterone measurements.

Do not use TRT as a Hashimoto's treatment. The presence of Hashimoto's does not establish testosterone deficiency.

Subclinical hypothyroidism

“Subclinical hypothyroidism” generally means TSH is elevated while free T4 remains within the reference range. Much of the classic literature linking hypothyroidism with testosterone changes comes from more overt thyroid dysfunction.

Do not assume a mildly high TSH explains a low testosterone result, and do not assume it cannot matter. Whether subclinical hypothyroidism needs treatment depends on the full clinical context.

Hyperthyroidism

This flips the SHBG story. Hyperthyroidism commonly raises SHBG. In the 2026 prospective cohort, treating hyperthyroidism lowered SHBG and total testosterone while free testosterone did not change significantly.[8]

That means a high or normal total testosterone during hyperthyroidism can be misleading in the opposite direction. The thyroid condition still deserves treatment and testosterone should be interpreted in context.

When the pituitary is the real problem

Your pituitary helps control both thyroid function and testicular function. It releases TSH to signal the thyroid and LH/FSH to help control the testes.

If pituitary function is impaired, both hormone systems can look abnormal at the same time. Endocrine Society guidance for hypopituitarism recommends measuring testosterone, LH, FSH, and prolactin when central hypogonadism is suspected, and it specifically warns that TSH should not be used to adjust thyroid replacement in central hypothyroidism.[12]

Start with an endocrinologist rather than an online TRT program if several of these fit you:

  • Free T4 is low but TSH is low or normal
  • Testosterone is clearly low and LH/FSH are low or inappropriately normal
  • Prolactin is persistently elevated
  • You have symptoms that could reflect a pituitary mass, such as new visual problems or persistent severe headaches
  • More than one pituitary-controlled hormone system looks abnormal
  • Your thyroid condition remains difficult to explain or control

None of this means you'll never need TRT. It means the cause should be found first.

Fertility: read this before you start TRT

Testosterone therapy can suppress sperm production, and the Endocrine Society recommends against starting TRT in men planning fertility in the near term. Thyroid dysfunction can affect reproductive health too. If a baby is in your near-term plans, a urologist or reproductive urologist is usually a better first stop than a general TRT program.[1]

Testosterone from outside the body suppresses the hypothalamic-pituitary-gonadal signals that support testicular testosterone production and spermatogenesis. That is why fertility has to be discussed before TRT, not after.[1]

If pregnancy is in your plans:

  • Get the thyroid problem properly evaluated and treated.
  • Tell the clinician that fertility matters before testosterone is prescribed.
  • Consider urology or reproductive urology when fertility is central.
  • Ask about non-testosterone treatments only with a clinician who can explain their actual approval status, evidence, risks, and whether they fit the cause of your low testosterone.

Clomiphene citrate is sometimes used off-label in men with hypogonadism, but it is not FDA-approved for that male indication.[14] hCG is a different medication and is not “TRT.” Enclomiphene is also not interchangeable with testosterone therapy.

We cannot promise whether one person will become infertile on TRT, preserve fertility, or recover sperm production on a set timeline. That uncertainty is exactly why this conversation comes first.

Questions to bring to your appointment

Bringing specific questions makes it easier to get the thyroid and testosterone evaluated together instead of one at a time. Copy or print this list.

About your thyroid

  1. Is my hypothyroidism adequately treated right now, and are my labs stable?
  2. When was my last levothyroxine dose change, and could that timing affect how we interpret my testosterone result?
  3. Is this ordinary primary hypothyroidism, or is there any reason to suspect pituitary or central hypothyroidism?

About your testosterone

  1. Were my testosterone tests done under appropriate early-morning conditions and repeated on a different day?
  2. Could low SHBG from thyroid disease be affecting my total testosterone?
  3. Would free testosterone add useful information in my case?
  4. If testosterone is truly low, what do LH and FSH suggest about the cause?
  5. Is prolactin or any additional pituitary testing appropriate?
  6. Could another medicine or health condition explain this result?

If testosterone therapy is being considered

  1. How would testosterone affect interpretation of my thyroid labs?
  2. When should my thyroid labs be rechecked after treatment starts?
  3. Who will manage my levothyroxine if thyroid results change?
  4. How does testosterone therapy fit my fertility plans?
  5. What else will be monitored, and how often?

What risks should you know about when you have both conditions?

Hypothyroidism does not erase the usual risks and monitoring needs of testosterone therapy. The thyroid-specific wrinkle is mainly lab interpretation and coordination between prescribers. Testosterone can raise hematocrit and suppress sperm production, while longer-term cardiovascular and prostate safety still require appropriate clinical judgment and monitoring.[1] [2]

What current evidence says:

  • Red blood cells. Testosterone can raise hematocrit. Endocrine Society guidance calls for hematocrit monitoring and lists elevated hematocrit among reasons not to start testosterone without addressing the issue.[1]
  • Heart attack and stroke. The TRAVERSE trial did not show a meaningful increase in major adverse cardiovascular events over its follow-up in the studied population; FDA's 2026 review likewise said it found no new cardiovascular safety signal from TRAVERSE.[2] [5]
  • Other safety signals remain. The Endocrine Society's 2026 statement highlights a roughly 50% relative increase in pulmonary embolism in TRAVERSE and a higher incidence of fractures among testosterone-treated men, while emphasizing that long-term safety questions remain.[2]
  • Fertility. Exogenous testosterone can suppress sperm production, so near-term fertility plans should be discussed before treatment.[1]
  • Thyroid labs. Androgens may lower TBG and total T4. That is a lab-interpretation issue, not proof by itself that hypothyroidism has worsened.[4] [13]

Get urgent or emergency care for severe or sudden symptoms such as chest pain, severe trouble breathing, sudden neurologic weakness, fainting, or other symptoms that may represent a medical emergency.

See also: TRT side effects and who should not take TRT.

Where should you get care if you have hypothyroidism and confirmed low testosterone?

If thyroid disease is stable and hypogonadism has been properly confirmed, care can come from primary care, urology, endocrinology, or an appropriate telehealth practice. The best route depends less on the label “TRT clinic” and more on whether your case still has unresolved thyroid, pituitary, fertility, insurance, or medication-formulation issues.

This is where many readers split into different paths:

TRT and hypothyroidism: thyroid labs, symptom overlap, evaluation and care routes table 6: Where should you get care if you have hypothyroidism and confirmed low testosterone?
Your priority Care route that usually deserves the first look Why
Thyroid is hard to control, central hypothyroidism is possible, or several hormones are abnormal Endocrinology The main problem is endocrine diagnosis, not provider shopping
Fertility is a near-term goal Urology or reproductive urology Exogenous testosterone can suppress spermatogenesis
Thyroid is stable, low testosterone is confirmed, and you want insurance or an FDA-approved testosterone product Local primary care, endocrinology, or urology Local prescribing can work through standard pharmacy and insurance pathways when appropriate
Thyroid is stable, low testosterone is confirmed, and you prefer remote cash-pay care Telehealth may be an option The program still needs a legitimate clinical evaluation, appropriate testing, monitoring, state availability, and lawful controlled-substance prescribing
You are still not sure whether your problem is thyroid, testosterone, pituitary, or fertility-related Find My TRT Path The decision is still about the correct care route, not which provider to buy from

Testosterone remains a Schedule III controlled substance in the United States.[6] Federal telemedicine flexibilities currently allow qualifying DEA-registered clinicians to prescribe Schedule II–V controlled substances by telemedicine without a prior in-person examination when the federal conditions are met, and the current temporary extension runs through December 31, 2026. State law and the clinician's licensing and DEA authority still apply.[7]

Completing a questionnaire, buying a test, or paying a membership fee does not guarantee a testosterone prescription.

Use Find My TRT Path →

Get the care route and the questions to ask before you pay.

How we built this page

We used current endocrine guidance for diagnosis and pituitary evaluation, official drug labeling for the levothyroxine–testosterone lab interaction, and published research for the thyroid–gonadal-axis evidence. The page was rechecked on October 26, 2026 and is editorial research, not clinical review.

  • Medical facts come from the Endocrine Society, FDA/DailyMed labeling, DEA/HHS, the American Thyroid Association, and published endocrine research.
  • Research findings are described with their limitations, including the small 2026 prospective cohort and the 2022 conference abstract.
  • Editorial judgments — such as “thyroid first when thyroid dysfunction may be confounding the result” and the care-route table — are conclusions from those sources, not a medical score.
  • What we did not do: we did not interpret an individual reader's lab results, enroll in a clinic for this page, or claim clinical review that did not occur.

Our provider-review process: How We Review TRT Providers.

Frequently asked questions

Can hypothyroidism cause low testosterone?

Yes. Hypothyroidism can lower SHBG, which can lower total testosterone, and it can affect the gonadal axis in some men.[8] [10] That is why a low testosterone result during thyroid dysfunction may need to be interpreted with SHBG, free testosterone when indicated, thyroid status, and repeat testing rather than treated as a diagnosis by itself.[1] [8]

Can levothyroxine increase testosterone?

Sometimes testosterone measurements improve as hypothyroidism is corrected, but it is not guaranteed. A 2022 conference abstract reported normalization in many men who began with low testosterone, while a small 2026 prospective cohort did not find a significant group-level rise in total or calculated free testosterone.[8] [9]

Can I take levothyroxine and testosterone together?

They are not simply a prohibited combination. Androgens can lower TBG, so total T4 can fall while free T4 and TSH remain normal in primary hypothyroidism.[4] [13] Your prescriber should interpret thyroid tests in context rather than adjusting levothyroxine from one number alone.

Does Synthroid affect TRT?

Levothyroxine does not by itself determine whether testosterone therapy will work. The more clearly documented interaction runs in the other direction: androgens can alter thyroid-hormone binding proteins and change total thyroid-hormone measurements.[4] [13]

Does TRT raise or lower TSH?

There is no reliable rule that TRT must raise or lower TSH in every person. Levothyroxine labeling describes lower TBG and total T4 with continued androgen use while free T4 and TSH remain normal.[4] If TSH changes, the prescriber should look at the full thyroid picture and the type of hypothyroidism.

Can I do TRT with Hashimoto's?

Hashimoto's alone does not establish or rule out testosterone deficiency. If Hashimoto's has caused hypothyroidism, treat and evaluate the thyroid problem and confirm whether hypogonadism remains before deciding on TRT.[1] [11]

Does TRT treat Hashimoto's or hypothyroidism?

No. Testosterone therapy is not thyroid-hormone replacement and is not a treatment for Hashimoto's disease or hypothyroidism.[11]

Can I take Armour Thyroid or another desiccated thyroid product with TRT?

The androgen-related TBG effect is not limited to one thyroid-replacement brand. Desiccated thyroid products also contain thyroid hormones, and the American Thyroid Association does not recommend desiccated thyroid extract as first-line therapy; treatment choice and monitoring belong with the thyroid prescriber.[11] [15]

Does hypothyroidism cause erectile dysfunction?

Thyroid dysfunction can contribute to sexual symptoms, including erectile dysfunction, but erection problems have many possible causes and cannot identify the hormone problem by themselves.[10]

Will fixing my thyroid fix my testosterone?

It might improve the testosterone picture, but there is no guarantee. The most useful next step is to treat/evaluate the thyroid problem appropriately and then confirm whether low testosterone persists with proper testing.[1] [8] [9]

Do online TRT clinics check your thyroid?

Some do and some do not, and testing menus change. Do not assume a clinic's testosterone panel includes a complete thyroid evaluation. If thyroid disease is part of your history, ask which thyroid markers are included, who interprets them, and who will coordinate changes with your thyroid prescriber.

Do I need an endocrinologist?

Not always. Endocrinology becomes especially useful when the thyroid is hard to control, free T4 is low with a low or normal TSH, testosterone is clearly low with an inappropriately low/normal LH/FSH pattern, prolactin is persistently elevated, or more than one pituitary-controlled hormone system looks abnormal.[12]

The bottom line on TRT and hypothyroidism

Hypothyroidism and low testosterone can happen together, and thyroid disease can also distort the testosterone picture. Treat and evaluate the thyroid problem, confirm low testosterone correctly, and then decide whether a separate hypogonadism diagnosis remains. If testosterone therapy starts later, remember that lower TBG can lower total T4 without automatically meaning your thyroid got worse.[1] [4] [8] [13]

You don't have to choose between thyroid treatment and testosterone. You have to find out which problems are actually present and handle them in the right order.

Still not sure which TRT care route fits you? Use our free Find My TRT Path tool.

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Sources

  1. Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018. Endocrine Society guideline
  2. Endocrine Society. Statement on Testosterone Replacement Therapy. July 16, 2026. Endocrine Society
  3. American Urological Association. Evaluation and Management of Testosterone Deficiency. 2018; validity confirmed 2024. AUA guideline
  4. Levothyroxine Sodium Tablets prescribing information. DailyMed. Current labeling checked October 26, 2026. DailyMed
  5. U.S. Food and Drug Administration. Testosterone Information. Content current June 23, 2026. FDA
  6. U.S. Drug Enforcement Administration. Drug Scheduling. Testosterone is listed among Schedule III substances. DEA
  7. U.S. Department of Health and Human Services. HHS & DEA Extend Telemedicine Flexibilities for Prescribing Controlled Medications Through 2026. January 2, 2026. HHS
  8. van Otzel RP, et al. Primary thyroid dysfunction and changes in the gonadal axis and SHBG in adult men: a prospective cohort study. European Thyroid Journal. 2026;15(5):ETJ260111. PubMed
  9. Shrivastav A, Saboo B. Effect of levothyroxine replacement therapy on testosterone, LH, FSH levels in men with overt hypothyroidism. Endocrine Abstracts. 2022;81:P730. Endocrine Abstracts
  10. Meikle AW. The interrelationships between thyroid dysfunction and hypogonadism in men and boys. Thyroid. 2004;14 Suppl 1:S17–25. See also Crawford M, Kennedy L. Testosterone replacement therapy: role of pituitary and thyroid in diagnosis and treatment. Transl Androl Urol. 2016;5(6). Full text
  11. American Thyroid Association. Thyroid Hormone Treatment. ATA
  12. Endocrine Society. Hormone Replacement in Hypopituitarism in Adults: Clinical Practice Guideline. Endocrine Society
  13. Testosterone Cypionate Injection prescribing information, section on decreased thyroxine-binding globulin. DailyMed
  14. Endocrine Society. Hypogonadism in Men. Patient resource noting clomiphene use in men is off-label. Endocrine Society
  15. American Thyroid Association. Statement on Desiccated Thyroid Extract. September 18, 2025. ATA

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