Hormone Guide · Spoke 20

Prolactin and Thyroid in Men: the overlooked axes

When testosterone and libido fade, the gaze almost always goes to the testes. Yet two quiet axes have a say that are often overlooked: prolactin and the thyroid. Both can co-steer the male hormone system from above. Whoever understands this measures more wisely and looks in the right place.

Shukri Jarmoukli · Physician, Integrative Medicine · ViveCura Berlin
My starting point

When a man comes with loss of libido and fatigue and his testosterone really is low, that is not the end of the search. It is the beginning. Because low testosterone with low signaling hormones is a hint that the problem lies further up, in the control center in the brain. This is exactly where prolactin and the thyroid come into play. Both are easily overlooked, because their complaints are so nonspecific. Yet they can change the whole picture. This article shows you why the second look is worth it.

Perhaps you know this. The desire is gone, the drive flat, perhaps things in bed no longer work as reliably. At the doctor testosterone is measured, it is low, and the obvious explanation reads: too little testosterone, so top up testosterone. Sometimes that is right. Sometimes it is only half the story. Because testosterone is the last step of a long chain of command that begins in the brain.

In this chain of command there are two players who are rarely named first. Prolactin, which can brake the control from above. And the thyroid, which through a binding protein co-determines how much testosterone circulates in the blood at all and stays active. This spoke article is devoted to exactly these two axes. We look at the mechanisms, at real studies, and at when which values make sense.

Prolactin: the quiet brake in the male hormone system

Most people know prolactin as the breastfeeding hormone in women. That the male body produces it too surprises many. In small amounts this is entirely normal and part of the healthy hormone concert. It becomes interesting when prolactin is persistently too high. This state is called hyperprolactinemia, and in men it can set a whole chain in motion.

The decisive point is the control. High up in the brain, in the hypothalamus, the hormone GnRH is released in pulses. It is the timekeeper that, through the pituitary gland, instructs the testes to build testosterone. Elevated prolactin can disturb this rhythm. It brakes the GnRH pulses, the signaling hormones LH and FSH fall, and testosterone may follow. The result is a so-called secondary or central hypogonadism, that is a testosterone deficiency whose root does not lie in the testes but in the control center above them.

Study · men with central hypogonadism

When prolactin falls, testosterone often recovers

Cohort, retrospective, n=29 Angelo Milioto and colleagues from Genoa investigated 29 men in 2025 in the journal Pituitary who had central hypogonadism from isolated hyperprolactinemia, mostly caused by a prolactinoma. After prolactin had been successfully lowered, around two thirds of the men reached normal testosterone values again, entirely without testosterone replacement. One part recovered immediately, another with a delay of a few months. Men with higher baseline testosterone recovered more readily. This suggests that the low testosterone in these cases is often a consequence of the elevated prolactin and not an independent damage of the testes.

Milioto A, Petolicchio C, Mattioli L, et al. Pituitary. 2025;28(4):75. doi:10.1007/s11102-025-01548-7 · PMID: 40544385

And now it becomes clear why the order of the workup matters so much. Whoever gives testosterone straight away for low testosterone and low signaling hormones may be treating the symptom and overlooking the cause up in the system. This is exactly why prolactin belongs on the lab list with this constellation of findings.

Reframe

A low testosterone value is an answer, not a diagnosis. When the signaling hormones LH and FSH are also low, that points upward, toward the brain. Prolactin and the thyroid are then two of the first questions, not the last. This is good news, because a recognized and treated cause from above can affect the whole system, rather than just replacing one value.

The prolactinoma: common, benign, often detected late in men

The most common cause of a marked hyperprolactinemia is a prolactinoma. This is a usually benign tumor of the pituitary gland that produces too much prolactin. It is the most common hormone-producing pituitary tumor of all. The word tumor sounds threatening at first, yet most prolactinomas are small and treatable.

In men there is a problem with time. Prolactinomas are often detected later in men than in women. In women a hyperprolactinemia draws attention early through cycle disturbances. In men it shows up as loss of libido, erectile problems, or fatigue, and these complaints are easily attributed to age, to stress, or to the job. So sometimes a lot of time passes before anyone thinks of prolactin.

Review · prolactinoma

Cabergoline as the preferred treatment, surgery as the second step

Review Andrea Glezer and Marcello Bronstein summarized the state of knowledge on prolactinoma in 2014 in the Arquivos Brasileiros de Endocrinologia e Metabologia. A hyperprolactinemia can cause low testosterone, sexual dysfunction, and infertility in men, and larger tumors can cause headaches and visual disturbances. Medical treatment with dopamine agonists is regarded as the standard, with cabergoline described as the first choice because of its efficacy and tolerability. In about one fifth of cases the medication works only partially, and then surgery may come into consideration. The interpretation belongs in specialist hands.

Glezer A, Bronstein MD. Arq Bras Endocrinol Metabol. 2014;58(2):118-23. doi:10.1590/0004-2730000002961 · PMID: 24830588

How often something at the pituitary gland really lies behind unclear men's complaints has been investigated more closely by researchers. An analysis from the Cleveland Clinic gives a helpful orientation here.

Study · men with mildly elevated prolactin

The ratio of prolactin to testosterone as a signpost

Cohort, retrospective, n=141 Bryan Naelitz and colleagues investigated 141 men in 2020 in the Journal of Urology who had symptoms of hypogonadism and only mildly elevated prolactin and who underwent imaging of the pituitary gland. In 28 percent the image showed an abnormality. Men with an abnormal image had higher prolactin, lower testosterone, and a markedly higher ratio of prolactin to testosterone. This ratio proved to be the best single predictor of whether the imaging shows something. This suggests that even simple blood values can help to select, in a targeted way, the men in whom imaging really makes sense.

Naelitz BD, Shah A, Nowacki AS, et al. J Urol. 2020;205(3):871-878. doi:10.1097/JU.0000000000001431 · PMID: 33080146

Common misconception

"A slightly elevated prolactin means a brain tumor right away." That is not so. Many things can temporarily raise prolactin: stress, physical exertion, a blood draw at the wrong time, certain medications, or an underactive thyroid. A single, slightly elevated value is therefore no reason to panic, but a reason to measure calmly and ideally repeatedly and to look at the other values alongside it. Only the overall picture decides whether imaging makes sense.

The thyroid: through SHBG right inside the testosterone level

Let us come to the second overlooked axis. The thyroid is the timekeeper of metabolism. It determines how fast the cells work. That it also has a hand in the testosterone level is less well known, but well founded. The main route runs through a binding protein with the unwieldy name SHBG, sex hormone-binding globulin.

SHBG is something like a taxi for testosterone in the blood. Only the unbound, free testosterone is immediately active. How much SHBG is present therefore changes how the testosterone is distributed. And this is exactly where the thyroid steps in. In an overactive thyroid SHBG rises, so more testosterone is bound. Total testosterone can then look high, although the free, active testosterone does not rise accordingly. In an underactive thyroid SHBG tends to fall, and total testosterone can appear lower. Whoever looks only at the total value can easily be misled here.

Study · genetic causal analysis

Thyroid function causally influences SHBG and testosterone

Mendelian randomization, n up to 252,514 Alisa Kjaergaard and colleagues used a genetic method in 2021 in the European Journal of Epidemiology, Mendelian randomization, to separate cause and effect. On the basis of large datasets they found that a higher thyroid signal TSH was causally linked with lower SHBG and lower testosterone. A genetic predisposition to an underactive thyroid lowered SHBG and testosterone, a predisposition to an overactive thyroid raised both. A direct effect on sexual function, by contrast, could not be demonstrated. This suggests that the thyroid intervenes in the testosterone balance mainly through the binding protein SHBG.

Kjaergaard AD, Marouli E, Papadopoulou A, et al. Eur J Epidemiol. 2021;36(3):335-344. doi:10.1007/s10654-021-00721-z · PMID: 33548002

An older but very clear review by A. Wayne Meikle from 2004 in the journal Thyroid frames the interplay further. A primary underactive thyroid can go along with a hypogonadotropic hypogonadism that can recede again under thyroid hormone replacement. In an underactive thyroid, prolactin can also rise and fall again after treatment. Men with an overactive thyroid have higher SHBG and testosterone values and more often a breast enlargement (doi:10.1089/105072504323024552, PMID: 15142373). And now you can see why the thyroid and prolactin belong together in this story. A pronounced underactive thyroid can set both axes in motion at once.

The four KPNI lenses on prolactin and the thyroid

In clinical psychoneuroimmunology, KPNI for short, we look not at a single hormone but at four interwoven levels. With prolactin and the thyroid this view is especially valuable, because both axes sit far up in the system and are influenced from several sides. Each lens explains one part at the cell level.

Nervous system and dopamine

Prolactin is under the constant brake of dopamine from the brain. As long as enough dopamine flows, prolactin stays low. Persistent stress, lack of sleep, or certain medications can disturb this braking system at the cell level and let prolactin rise. Here it shows why hormone control is not an isolated gland topic, but closely coupled to the nervous system. The brain is the conductor, not just the spectator.

Immune system and inflammation

The most common form of an underactive thyroid in our latitudes is an autoimmune disease in which the immune system attacks the body's own thyroid tissue. At the cell level, inflammatory processes lead to a declining hormone production. The thyroid is thus a good example of how the immune system can indirectly reach into the hormone balance and through SHBG right into the testosterone level. Hormones and the immune system are not separate worlds.

Metabolism and tempo

The thyroid determines the metabolic tempo of every cell. It influences how much SHBG the liver builds, and with it how the testosterone is distributed in the blood. A slowed metabolism in an underactive thyroid can bring fatigue, weight gain, and low drive, that is exactly the complaints that a testosterone deficiency also makes. At the cell level these pictures overlap, which makes the distinction in everyday life harder.

Hormone system and control center

Here the threads come together. Hypothalamus and pituitary gland steer the testes through GnRH, LH, and FSH. Prolactin can brake this chain from above, the thyroid modulates through SHBG and through prolactin. Whoever wants to understand testosterone has to think of this upper floor too. A single number always describes only a section of an interconnected system whose control begins in the head.

These four lenses are no theoretical model. They are the reason why a good workup for loss of libido and low testosterone does not stop at testosterone. And now you know why prolactin and the thyroid are so often the missing puzzle pieces.

Thyroid, erection, and mood: an underrated connection

The thyroid acts not only through lab values. It can also make itself felt directly in the sex life and in the mood. Both an overactive and an underactive thyroid are associated with sexual dysfunction in men. This is clinically relevant, because it means the thyroid belongs on the test bench for erectile problems.

Study · men with erectile problems

Hidden underactive thyroid common in erectile disorders

Case-control study, n=141 Dawei Chen and colleagues investigated 109 men with erectile problems and 32 healthy comparison persons in 2018 in the Pakistan Journal of Medical Sciences. Among the men with erectile problems, almost one in three had a hidden, so-called subclinical underactive thyroid. These men had higher TSH and prolactin values and lower values of the free thyroid hormone as well as worse scores in a questionnaire on erectile function. The authors recommend that the thyroid be evaluated in men with erectile problems. This suggests that the thyroid can be an easily overlooked player in erectile disorders.

Chen D, Yan Y, Huang H, Dong Q, Tian H. Pak J Med Sci. 2018;34(3):621-625. doi:10.12669/pjms.343.14330 · PMID: 30034427

That a treatment of the thyroid could change more than just lab values is shown by a small controlled investigation. Robert Krysiak and colleagues found in 2017 in the Pharmacological Reports a worse sexual function and more depressive symptoms in men with an autoimmune underactive thyroid than in healthy men. Under six months of treatment with thyroid hormone, erectile function improved, and in the pronounced underactive thyroid the depressive symptoms also decreased (doi:10.1016/j.pharep.2017.01.005, PMID: 28315587). The groups were small, so restraint is appropriate. But the direction is plausible and fits the mechanism.

A broad review by Rohan Morenas and colleagues in 2023 in the International Journal of Impotence Research frames the field. It describes that thyroid disorders can contribute to sexual dysfunction in men through several routes, from erectile and ejaculatory disorders to a disturbed control of the testicular axis, and it argues for thinking of the thyroid in the workup (doi:10.1038/s41443-023-00768-4, PMID: 37752332). And now you know why the thyroid is more than a metabolic topic.

When which values? A sober orientation

This brings us to the practical question that occupies many men. When is it worth measuring prolactin and the thyroid alongside, and what matters there? Up front: this section does not replace a medical workup. It is meant to help you ask the right questions.

The most important hint is the constellation of findings. When a low testosterone occurs together with low or inappropriately normal signaling hormones LH and FSH, that points upward toward the brain. Exactly then prolactin and the thyroid are obvious next steps. A review by Shiri Levy and colleagues in 2019 in the Current Urology Reports stresses that with low gonadotropins, reversible causes in the hypothalamic-pituitary axis should be considered, and that men with a small prolactinoma stand out more with sexual complaints, while larger tumors tend to make problems through their size (doi:10.1007/s11934-019-0935-z, PMID: 31734886).

With a breast enlargement the look at both axes is especially worthwhile, because both a hyperprolactinemia and an overactive thyroid are among the possible causes. A review by Andrea Sansone and colleagues in 2016 in the journal Endocrine describes that a true gynecomastia often arises from an imbalance between estrogen and androgen and names hyperprolactinemia and an overactive thyroid explicitly among the hormone disorders to be evaluated (doi:10.1007/s12020-016-0975-9, PMID: 27145756).

With the prolactin measurement itself, care pays off at the blood draw. Stress, physical exertion, and some stimuli can briefly raise the value. A single slightly elevated value should therefore be checked calmly and ideally repeated before further steps follow. The medication list belongs to this too, because some agents can raise prolactin without a tumor being behind it. A comprehensive review on pituitary insufficiency reminds us that in men a hypogonadotropic hypogonadism goes along with low testosterone and low or normal LH and FSH, and that hyperprolactinemia and a low SHBG belong in the differential diagnosis (doi:10.1007/s11102-006-0416-5, PMID: 17077946).

Three levers you hold in your own hands

First the most important thing: a prolactinoma and a true thyroid disorder belong in specialist care. No lifestyle lever replaces a medical workup or a necessary therapy. These three levers are a start and a stance, not a treatment plan. You will find the individual path with medical guidance.

1

Insist on the complete constellation of findings

When your testosterone is low, ask for the signaling hormones LH and FSH as well as for prolactin and the thyroid values. This combined view shows whether the problem lies in the testes or further up in the system. It is no distrust of your doctor, but a contribution to good diagnostics. A complete snapshot can prevent a treatable cause from above being overlooked.

2

Look at stress, sleep, and the dopamine brake

Prolactin is under the brake of dopamine, and this brake responds to sleep and stress. Restful sleep and an honest stress regulation can support the nervous system that co-steers this axis. This is no guarantee and does not replace the workup of a clearly elevated value. But it is a sensible foundation that can benefit the whole interconnected system, not just a single hormone.

3

Check the medication list together with your doctor

Some medications can raise prolactin by acting on the dopamine system. When your prolactin is abnormal, the joint look at everything you take regularly is worthwhile. Never stop a prescribed medication on your own. Discuss anything unusual with the doctor who prescribed the medication. This can often clarify whether a value has a harmless explanation.

And when the complaints remain despite good foundations, a workup belongs to it that keeps the whole picture in view. Testosterone, LH, FSH, prolactin, and thyroid values together give a much clearer picture than a single value. This way treatable causes can be found, rather than attributing complaints prematurely to one hormone. A good workup takes your complaints seriously.

The core

Sometimes the answer lies one floor up

Your testosterone is the last step of a long chain of command that begins in the brain. When the values do not fit together, the look upward is worthwhile, toward prolactin and the thyroid. These two quiet axes can explain the whole picture. You do not have to solve everything yourself. But you may ask the right questions and insist on a workup that sees the whole system.

Frequently asked questions about prolactin and the thyroid in men

What does prolactin do in men?

Prolactin is best known as the breastfeeding hormone in women, but the male body produces it too, in the pituitary gland. In small amounts this is normal. It becomes a problem when prolactin is persistently elevated, a condition called hyperprolactinemia. Elevated prolactin can dampen the higher control of the testes by slowing the pulsing release of the signaling hormone GnRH. As a result LH and FSH fall, and testosterone may follow. This is often felt as fading libido, erectile problems, fatigue, or rarely breast enlargement. Prolactin is thus a quiet player in the male hormone system that belongs on the lab list when complaints are unclear.

Can elevated prolactin cause testosterone deficiency?

Yes, a marked hyperprolactinemia is a recognized cause of secondary, that is centrally driven, hypogonadism in men. The mechanism runs through the brain: elevated prolactin slows the release of GnRH from the hypothalamus, the signal to the testes drops, and testosterone production may decline. It is important that not every slightly elevated value is to blame. Stress, certain medications, an underactive thyroid, or a blood draw at the wrong time can temporarily raise prolactin. Only a repeatedly and clearly elevated value, together with low testosterone and matching complaints, points toward a relevant hyperprolactinemia that needs further evaluation.

What is a prolactinoma?

A prolactinoma is a usually benign tumor of the pituitary gland that produces too much prolactin. It is the most common hormone-producing pituitary tumor. In men a prolactinoma is often detected later than in women, because complaints such as loss of libido or erectile problems are more easily attributed to other causes. Larger prolactinomas, so-called macroprolactinomas, can additionally exert pressure through their size and cause headaches or visual disturbances. The diagnosis rests on repeatedly elevated prolactin values and imaging of the pituitary gland. Treatment is usually with medication that can lower prolactin and shrink the tumor. This belongs in specialist hands.

How does the thyroid influence testosterone?

The thyroid acts on testosterone mainly through a binding protein called SHBG, sex hormone-binding globulin. In an overactive thyroid SHBG rises, so more testosterone is bound and total testosterone can appear high, while the free, active testosterone does not rise accordingly. In an underactive thyroid SHBG tends to fall, and total testosterone can come out lower. A genetic study suggests that this connection through SHBG is causal. In addition, a pronounced underactive thyroid can raise prolactin and so indirectly dampen the control of the testes. This is why the thyroid belongs on the lab list when testosterone values are unclear.

Which symptoms can point to elevated prolactin?

Possible signs are fading libido, erectile problems, fatigue, low drive, reduced resilience, and more rarely breast enlargement or a milky discharge from the breast. With a larger prolactinoma, headaches or visual disturbances can be added. These complaints are nonspecific and overlap strongly with those of testosterone deficiency from other causes. This is exactly what makes prolactin an easily overlooked factor. Anyone being evaluated for loss of libido or erectile problems should therefore also keep an eye on prolactin and the thyroid, not on testosterone alone.

When should prolactin be measured?

A prolactin value makes sense when low testosterone comes together with complaints, especially loss of libido, erectile problems, or breast enlargement, and when the signaling hormones LH and FSH are low or inappropriately normal. Care pays off with the blood draw, because stress, physical exertion, and certain stimuli can briefly raise the value. A single slightly elevated value should therefore be checked calmly and ideally repeated before further steps follow. With clearly elevated or repeatedly abnormal values, imaging of the pituitary gland may be indicated. The interpretation belongs in medical hands.

Does testosterone improve when prolactin is treated?

In many men the control of the testes recovers when the cause of the hyperprolactinemia is treated and prolactin is lowered. An observational study in men with central hypogonadism from isolated hyperprolactinemia found that a large share reached normal testosterone values on their own after prolactin normalized, some immediately, some with a delay of a few months. Those with higher baseline testosterone recovered more readily. This suggests that testosterone in these cases is often a consequence of the elevated prolactin and not an independent defect of the testes. Treatment belongs in specialist care, rather than reaching straight for plain testosterone replacement.

Can a thyroid disorder cause erectile problems?

Both an overactive and an underactive thyroid are associated with sexual dysfunction in men, including erectile and ejaculatory problems. Studies found a hidden underactive thyroid more often in men with erectile problems, and in small investigations erectile function improved under treatment with thyroid hormone. The connection is layered, because the thyroid influences metabolism, mood, the binding protein SHBG, and through the stress level also the hormone control indirectly. This is one reason why the thyroid belongs in the workup for newly arising erectile problems, rather than looking at testosterone alone.

Which medications can raise prolactin?

A whole range of medications can raise prolactin without a tumor being behind it. These include above all certain remedies against nausea and some psychiatric drugs that act on the dopamine system, because dopamine is the natural brake on prolactin. When this brake is released by a medication, prolactin can rise. A pronounced underactive thyroid can also raise the value. This is why, with an abnormal prolactin value, it is important to check the medication list and the thyroid before evaluating further. Never stop a prescribed medication on your own, but discuss anything unusual with a doctor.

When should I see a doctor with these complaints?

You should have a medical workup for persistent loss of libido, newly arising erectile problems, unexplained fatigue, breast enlargement or a milky discharge from the breast, as well as headaches with visual disturbances. The combination of low testosterone with low signaling hormones in particular should lead to a measurement of prolactin and the thyroid. Behind such complaints there can be well treatable causes, from a thyroid disorder through medication effects to a prolactinoma. A careful workup looks at the whole picture and not at a single value. If you have low moods that do not lift, or thoughts of no longer wanting to live, please get help right away.

Connections to other topics

When the value is lowUnderstanding testosterone deficiency

The deeper framing of when a low value is really a deficiency and which causes from above in the system can lie behind it.

When the thyroid is borderlineFunctional underactive thyroid

Why normal values are not always enough and how a borderline thyroid can co-influence drive, mood, and testosterone through SHBG.

When stress is the themeCortisol and the HPA axis in burnout

The stress axis shares the control center with the hormone control and can co-influence prolactin through the nervous system.

The other side of the hormonesHormonal imbalance in women

How female hormones work as an interconnected system, with many parallels to the role of prolactin and the thyroid in men.

When the energy is missingIron deficiency and iron infusions

Iron deficiency intensifies many complaints that look like a pure hormone problem, from exhaustion to reduced stamina.

When the gut is involvedGut reset: holistic gut treatment

The gut co-influences, through the immune system and silent inflammation, how well the thyroid and hormone balance stay in equilibrium.

SJ
Written by

Shukri Jarmoukli

Physician, Integrative Medicine, Clinical Psychoneuroimmunology · ViveCura Berlin, Skalitzer Straße 137 · Focus: male hormones as an interconnected system. With unclear testosterone values I look not only at the testes but at the control center above them, at prolactin and the thyroid, at the signaling hormones LH and FSH, and at the binding protein SHBG. This spoke draws on the research into the recovery of testosterone after lowering prolactin (Milioto 2025, Pituitary), into the role of the prolactin-to-testosterone ratio (Naelitz 2020, Journal of Urology), into the causal influence of the thyroid through SHBG (Kjaergaard 2021, European Journal of Epidemiology), as well as into the thyroid and sexual function (Chen 2018, Pakistan Journal of Medical Sciences; Morenas 2023, International Journal of Impotence Research). My aim is a men's consultation that takes the whole system seriously, not just one number.

Sources and further reading

  1. Milioto A, Petolicchio C, Mattioli L, et al. Baseline testosterone levels as a predictor of hypogonadism resolution in male patients with isolated hyperprolactinemia. Pituitary. 2025;28(4):75. doi:10.1007/s11102-025-01548-7 · PMID: 40544385 [Cohort, retrospective]
  2. Cheng X, Xiao Y, Deng Y, et al. Idiopathic hyperprolactinemia-associated hypogonadism in men presenting with normal testosterone levels. PLoS One. 2025;20(9):e0332871. doi:10.1371/journal.pone.0332871 · PMID: 40966237 [Case, retrospective]
  3. Naelitz BD, Shah A, Nowacki AS, et al. Prolactin-to-Testosterone Ratio Predicts Pituitary Abnormalities in Mildly Hyperprolactinemic Men with Symptoms of Hypogonadism. J Urol. 2020;205(3):871-878. doi:10.1097/JU.0000000000001431 · PMID: 33080146 [Cohort, retrospective]
  4. Glezer A, Bronstein MD. Prolactinoma. Arq Bras Endocrinol Metabol. 2014;58(2):118-23. doi:10.1590/0004-2730000002961 · PMID: 24830588 [Review]
  5. Kjaergaard AD, Marouli E, Papadopoulou A, et al. Thyroid function, sex hormones and sexual function: a Mendelian randomization study. Eur J Epidemiol. 2021;36(3):335-344. doi:10.1007/s10654-021-00721-z · PMID: 33548002 [Cohort, Mendelian randomization]
  6. Meikle AW. The interrelationships between thyroid dysfunction and hypogonadism in men and boys. Thyroid. 2004;14 Suppl 1:S17-25. doi:10.1089/105072504323024552 · PMID: 15142373 [Review]
  7. Morenas R, Singh D, Hellstrom WJG. Thyroid disorders and male sexual dysfunction. Int J Impot Res. 2023;36(4):333-338. doi:10.1038/s41443-023-00768-4 · PMID: 37752332 [Review]
  8. Chen D, Yan Y, Huang H, Dong Q, Tian H. The association between subclinical hypothyroidism and erectile dysfunction. Pak J Med Sci. 2018;34(3):621-625. doi:10.12669/pjms.343.14330 · PMID: 30034427 [Case, case-control study]
  9. Krysiak R, Szkróbka W, Okopień B. The effect of l-thyroxine treatment on sexual function and depressive symptoms in men with autoimmune hypothyroidism. Pharmacol Rep. 2017;69(3):432-437. doi:10.1016/j.pharep.2017.01.005 · PMID: 28315587 [Case, controlled]
  10. Levy S, Arguello M, Macki M, Rao SD. Pituitary Dysfunction Among Men Presenting with Hypogonadism. Curr Urol Rep. 2019;20(11):78. doi:10.1007/s11934-019-0935-z · PMID: 31734886 [Review]
  11. Sansone A, Romanelli F, Sansone M, Lenzi A, Di Luigi L. Gynecomastia and hormones. Endocrine. 2016;55(1):37-44. doi:10.1007/s12020-016-0975-9 · PMID: 27145756 [Review]
  12. Ascoli P, Cavagnini F. Hypopituitarism. Pituitary. 2006;9(4):335-42. doi:10.1007/s11102-006-0416-5 · PMID: 17077946 [Review]
A note on the evidence: This spoke article combines well-established connections with areas in which the research is still in flux. It is solidly established that a marked hyperprolactinemia in men can trigger a central hypogonadism and that testosterone recovers in many men after prolactin is lowered (Milioto 2025, Naelitz 2020, Glezer 2014). The influence of the thyroid on SHBG and testosterone is supported by a large genetic analysis (Kjaergaard 2021) and well described mechanistically (Meikle 2004). The connection between the thyroid and sexual function rests partly on smaller studies that should be read with restraint (Chen 2018, Krysiak 2017, Morenas 2023). This text serves information and does not replace a medical examination, diagnosis, or treatment. A prolactinoma and a thyroid disorder needing treatment belong in specialist hands. Never stop prescribed medications on your own. With persistent loss of libido, newly arising erectile problems, a breast enlargement, a milky discharge from the breast, or headaches with visual disturbances, a medical workup should take place. If you have low moods that do not lift, or thoughts of no longer wanting to live, please get medical or psychotherapeutic help without delay.

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