Hormones are the body’s chemical messengers, influencing everything from mood and energy to metabolism and fertility. When they are balanced, the body works in harmony. But when one hormone is off, it can trigger a cascade of effects. A common question many patients ask is: does hypothyroidism cause low testosterone? The connection between thyroid health and testosterone levels is more significant than many realize. Both men and women may experience frustrating and sometimes confusing symptoms when these hormones are out of balance.

Understanding the thyroid-testosterone link is critical for identifying the root cause of fatigue, weight gain, mood changes, or fertility struggles. For men, low testosterone often translates into reduced energy and muscle mass. For women, it may cause irregular periods, low libido, or bone health issues. Exploring how hypothyroidism contributes to low testosterone can empower patients to seek the right diagnosis and treatment.

In this blog, we’ll break down the science of thyroid and testosterone, explain how they interact, explore overlapping symptoms, and discuss available treatment options. By the end, you’ll know how to identify signs of imbalance, why testing is vital, and the best strategies to restore health. Whether you live in NYC or elsewhere in the USA, understanding this hormonal connection can be the key to reclaiming your vitality.

Understanding Hypothyroidism and Testosterone

Hypothyroidism occurs when the thyroid gland fails to produce enough thyroid hormones (T3 and T4). This butterfly-shaped gland, located at the base of the neck, regulates metabolism, body temperature, and energy levels. When the thyroid slows down, nearly every system in the body is impacted.

Causes of hypothyroidism include:

• Autoimmune disorders like Hashimoto’s thyroiditis.
• Iodine deficiency.
• Medications such as lithium or amiodarone.
• Radiation treatment or surgical removal of the thyroid.
• Pituitary gland dysfunction.

Connection to hormone health: Thyroid hormones regulate how cells use energy. If they are insufficient, the pituitary and hypothalamus adjust hormone signals throughout the body, including those involved in testosterone production.

Symptoms of hypothyroidism include:

• Fatigue and sluggishness.
• Weight gain despite no diet changes.
• Cold intolerance.
• Depression and mood swings.
• Hair thinning and dry skin.
• Slow heart rate and swelling in the face or neck.

What is Testosterone?

Testosterone is a sex hormone produced primarily in the testes in men and in smaller amounts in the ovaries and adrenal glands in women. While best known for driving male sexual development, testosterone plays a vital role in both sexes.

Key functions of testosterone:

• Regulates libido and sexual performance
  
• Supports muscle growth and strength
  
• Maintains bone density
  
• Influences energy and mood
  
• Affects red blood cell production
  
• Supports fertility in both men and women
  

When testosterone levels fall, men often experience fatigue, reduced muscle mass, erectile dysfunction, and mood swings. Women may notice decreased libido, irregular cycles, bone weakness, and low energy.

Because both thyroid hormones and testosterone are interlinked through the endocrine system, disruption in one often impacts the other.

Roles of testosterone in men:

• Development of male sexual characteristics.
• Muscle mass and strength.
• Libido and erectile function.
• Sperm production and fertility.
• Mood regulation and motivation.

Roles of testosterone in women:

• Bone density and strength.
• Libido and sexual satisfaction.
• Red blood cell production.
• Hormonal balance alongside estrogen and progesterone.

When hormone imbalances occur, energy, fertility, and mood are strongly affected. Low testosterone contributes to fatigue, irritability, and reduced motivation. In women, it may worsen menopausal symptoms or lead to decreased fertility.

Does Hypothyroidism Cause Low Testosterone?

The connection between hypothyroidism and low testosterone is stronger than many realize. The thyroid gland plays a central role in regulating hormones throughout the body, including those that influence reproductive health. When thyroid hormone production slows down, the balance of the entire endocrine system shifts, often leading to a low thyroid count and disrupted testosterone production.

Research has shown that individuals with hypothyroidism frequently experience lower levels of sex hormones. This is because the thyroid doesn’t just regulate metabolism—it also communicates with the hypothalamus and pituitary gland, two critical hormone control centers. When thyroid hormones are deficient, these signals weaken, which can suppress testosterone levels in both men and women.

The real challenge lies in how similar the symptoms of hypothyroidism and low testosterone appear. Fatigue, weight gain, depression, and sexual dysfunction can occur in either condition, making it difficult to pinpoint the root cause without proper testing. Misdiagnosis is common, leading to unnecessary treatments or untreated health issues.

So, does hypothyroidism cause low testosterone? Yes, in many cases, it does. The thyroid and testosterone share a deeply interwoven relationship, and treating thyroid dysfunction often helps normalize testosterone naturally. However, for some people, dual treatment—addressing both the thyroid and testosterone—may be required for full recovery.

The Hormonal Link Between Thyroid and Testosterone

Medical research shows a strong connection between thyroid hormones and testosterone regulation. Thyroid hormones influence the hypothalamic-pituitary-gonadal (HPG) axis, the system responsible for testosterone production.

When thyroid hormone levels are low:

• The pituitary gland may release abnormal levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
  
• These hormones signal the testes (in men) and ovaries (in women) to produce testosterone.
  
• With disrupted signaling, testosterone levels often decline.
  

A low thyroid count does not always guarantee low testosterone, but studies suggest that untreated hypothyroidism is a common hidden cause of testosterone deficiency.

Effects of Low Thyroid Count on Men

Men are often the most visibly affected by the relationship between thyroid and testosterone. Since testosterone is their primary sex hormone, even small changes can create noticeable symptoms. When a man has hypothyroidism, his testosterone levels often decline, leading to issues that affect both physical and emotional well-being.

Common effects of hypothyroidism on men’s testosterone include:

• Fatigue and reduced stamina – Even with rest, energy levels remain low.
  
• Loss of muscle mass and strength – Testosterone is key for maintaining lean muscle.
  
• Sexual dysfunction – Reduced libido, erectile dysfunction, and infertility are common.
  
• Mood changes – Irritability, depression, or lack of motivation often occur.
  
• Cognitive decline – Brain fog and memory issues may develop.
  

For men in NYC and across the USA, these symptoms are often misattributed to aging, stress, or lifestyle. However, when both thyroid and testosterone are tested, a clear link emerges. Treatment of the thyroid alone sometimes restores testosterone naturally, but in cases of severe deficiency, TRT (Testosterone Replacement Therapy) may be necessary alongside thyroid therapy.

Low Thyroid Symptoms in Women and Testosterone Levels

While testosterone is often thought of as a “male hormone,” it is equally important for women—just in smaller amounts. Women with hypothyroidism face unique challenges because thyroid dysfunction impacts not only testosterone but also estrogen and progesterone. This triple imbalance can intensify symptoms and disrupt overall health.

Common Low Thyroid Symptoms in Women

Women experience more thyroid-related conditions than men, making this issue especially relevant. Low thyroid function disrupts reproductive hormones, often leading to irregular menstrual cycles or ovulation problems.

Typical symptoms include:

• Chronic fatigue and sluggishness
  
• Unexplained weight gain despite diet and exercise
  
• Hair loss or thinning
  
• Cold intolerance
  
• Depression and anxiety
  
• Irregular or heavy menstrual periods
  
• Dry skin and brittle nails
  

Since many of these also overlap with low testosterone symptoms, women often face an uphill battle in identifying the true cause of their discomfort.

Can Hypothyroidism Lower Testosterone in Women?

Yes, hypothyroidism can directly lower testosterone levels in women. Unlike men, who rely primarily on testes, women produce testosterone in both the ovaries and adrenal glands. When thyroid hormones are imbalanced, the ovarian cycle and adrenal function become disrupted, leading to reduced testosterone.

Effects of low testosterone in women with hypothyroidism include:

• Low libido and reduced sexual satisfaction
  
• Infertility challenges due to irregular ovulation
  
• Weakened bones (osteopenia or osteoporosis risk)
  
• Loss of lean muscle tone despite exercise
  
• Mood swings and irritability
  

This combined hormonal imbalance can feel overwhelming. For many women, simply treating the thyroid restores balance and improves testosterone naturally. However, in cases where symptoms persist, a doctor may recommend additional hormone support to stabilize both thyroid and testosterone.

Symptoms of Hypothyroidism vs. Symptoms of Low Testosterone

The overlap between hypothyroidism and low testosterone often confuses both patients and healthcare providers. While the symptoms are similar, there are key differences to help distinguish one from the other.

Overlapping Symptoms

Because both conditions affect energy and metabolism, their symptoms often overlap. This explains why many patients are misdiagnosed.

Both conditions can cause:

• Persistent fatigue
  
• Weight gain or difficulty losing weight
  
• Depression or mood swings
  
• Low libido and sexual dysfunction
  
• Infertility challenges
  

These overlaps explain why someone with hypothyroidism may mistakenly believe they only have low testosterone—or vice versa.

Key Differences to Watch For

While similar, each condition also has distinct symptoms:

• Hypothyroidism specific signs: Dry skin, constipation, cold intolerance, swelling in the neck, hair loss at the outer eyebrows.
• Low Testosterone specific signs: Erectile dysfunction in men, reduced body hair, night sweats, hot flashes, and decreased muscle tone.

Symptom	Hypothyroidism	Low Testosterone
Hair Changes	Dry, brittle hair; scalp thinning	Loss of body/facial hair in men
Energy Levels	Slow metabolism; constant fatigue	Fatigue combined with muscle weakness
Fertility Issues	Irregular or heavy menstrual cycles (women)	Reduced sperm count; erectile dysfunction
Temperature Sensitivity	Cold intolerance	Not typically linked
Bone Health	Secondary risk from prolonged imbalance	Directly linked to decreased bone density

Understanding these distinctions is critical. Misdiagnosis is common without blood tests, which is why comprehensive hormone testing is always recommended.

Why misdiagnosis is common: Both conditions share hallmark symptoms like fatigue and depression, making comprehensive lab tests the only reliable way to differentiate them.

Diagnosing Hormone Imbalances

The only way to truly know if hypothyroidism is causing low testosterone is through comprehensive testing. Symptoms alone can be misleading, since fatigue, mood swings, and weight gain overlap across multiple conditions. A hormone specialist—such as those found in top clinics in NYC—will typically recommend a full panel to measure thyroid function, testosterone levels, and related markers.

Accurate diagnosis is crucial not just for effective treatment, but also for avoiding unnecessary therapies. For example, some men may be placed on Testosterone Replacement Therapy (TRT) when the real issue is an untreated low thyroid count. Similarly, women experiencing infertility may go undiagnosed with hypothyroidism for years if proper testing isn’t done.

Tests for Hypothyroidism

Doctors usually start with thyroid-specific blood tests, which include:

• TSH (Thyroid Stimulating Hormone): Elevated TSH usually indicates hypothyroidism, since the pituitary is working harder to stimulate the thyroid.
  
• Free T4 (Thyroxine): Measures the actual thyroid hormone available in the bloodstream. Low levels confirm underactive thyroid function.
  
• Free T3 (Triiodothyronine): While less commonly tested, T3 is the active form of thyroid hormone and can reveal conversion problems.
  
• Thyroid Antibodies (TPOAb, TgAb): These detect autoimmune conditions like Hashimoto’s thyroiditis, the leading cause of hypothyroidism in the U.S.
  

Together, these tests give a complete picture of thyroid function and can identify whether hypothyroidism is impacting testosterone production.

Tests for Low Testosterone

If thyroid tests reveal abnormalities, most physicians will also check testosterone levels, especially in men. Standard tests include:

• Total Testosterone: Measures the overall amount of testosterone in the blood.
  
• Free Testosterone: The most accurate marker, since it reflects the biologically active testosterone available to the body.
  
• SHBG (Sex Hormone-Binding Globulin): High SHBG can reduce free testosterone, often influenced by thyroid disorders.
  
• LH and FSH: Help determine if the issue originates in the testes/ovaries or from pituitary-thyroid signaling.
  

For men in NYC, many clinics offer same-day blood testing with results available in 24–48 hours. Women may also benefit from hormone panels that assess thyroid, testosterone, estrogen, and progesterone together, since these hormones are tightly connected.

Why Testing Matters

Testing is not just about confirming a diagnosis—it’s about preventing long-term complications. Left undiagnosed, hypothyroidism and low testosterone can contribute to:

• Infertility in men and women
  
• Osteoporosis and bone fractures
  
• Cardiovascular disease and high cholesterol
  
• Cognitive decline and depression
  

By catching hormone imbalances early, patients can begin treatment sooner, often avoiding more aggressive therapies. In many cases, treating hypothyroidism alone can normalize testosterone levels, eliminating the need for TRT.

For anyone in NYC experiencing symptoms of hypothyroidism or low testosterone, scheduling a hormone panel with a trusted clinic is the first step toward recovery.

Treatment Options and Lifestyle Strategies

When it comes to managing hypothyroidism and low testosterone, treatment is highly individualized. Some patients only require thyroid support, while others may need combined therapy that addresses both conditions. The goal is always to restore balance, reduce symptoms, and improve long-term health.

Medical Treatments for Hypothyroidism

The most common and effective treatment is thyroid hormone replacement therapy, usually prescribed as:

• Levothyroxine (Synthetic T4): The standard treatment for most patients.
  
• Combination Therapy (T4 + T3): For those who don’t respond well to levothyroxine alone.
  
• Natural Desiccated Thyroid (NDT): A less common option made from animal thyroid glands, sometimes preferred by patients seeking alternative approaches.

Regular monitoring is critical. Over- or under-treatment can lead to further hormone imbalances, worsening testosterone issues.

TRT and Hormone Therapy for Low Testosterone

When hypothyroidism treatment does not fully restore testosterone, Testosterone Replacement Therapy (TRT) may be considered, especially in men.

TRT options include:

• Injections: Administered weekly or bi-weekly.
  
• Topical gels or creams: Applied daily.
  
• Pellets: Implanted under the skin, lasting several months.
  
• Patches: Slow-release over 24 hours.

For women, testosterone therapy is used more cautiously but can improve libido, bone health, and energy when combined with thyroid treatment.

It’s important to work with an experienced hormone specialist, as improper dosing can lead to side effects. NYC clinics like TRTNYC offer personalized protocols based on comprehensive lab work.

Lifestyle Approaches

While medical treatment forms the foundation, lifestyle adjustments play a huge role in supporting thyroid and testosterone health.

Key strategies include:

• Diet: Focus on whole foods rich in iodine, selenium, and zinc (found in fish, nuts, and eggs). Avoid ultra-processed foods that disrupt hormone balance.
  
• Exercise: Strength training boosts testosterone naturally, while cardio supports thyroid function and metabolism.
  
• Stress management: Chronic stress elevates cortisol, which suppresses both thyroid and testosterone production. Meditation, yoga, or therapy can help.
  
• Sleep hygiene: Aim for 7–9 hours of quality sleep to allow hormonal cycles to reset.

For many patients, these changes reduce reliance on medication and enhance overall treatment success.

Long-Term Effects of Untreated Hypothyroidism on Testosterone

Failing to treat hypothyroidism doesn’t just worsen fatigue and weight gain—it also poses serious risks for testosterone and overall health.

1. Fertility Challenges

• In men, untreated hypothyroidism can cause low sperm count and erectile dysfunction.
  
• In women, ovulation becomes irregular, lowering fertility and increasing miscarriage risk.
  

2. Bone Health Risks

• Both hypothyroidism and low testosterone contribute to decreased bone density.
  
• Without treatment, osteoporosis and fractures become more likely, particularly in women post-menopause.
  

3. Cardiovascular Issues

• Hypothyroidism raises LDL cholesterol and triglycerides.
  
• Low testosterone weakens heart muscle and blood vessel health.
  
• Together, they significantly increase cardiovascular risk.

Ultimately, untreated thyroid dysfunction has a domino effect—damaging testosterone levels, reproductive health, bones, and heart health. Early intervention prevents these complications and improves long-term quality of life.

Comparison Table: Hypothyroidism vs. Low Testosterone

Feature	Hypothyroidism	Low Testosterone
Primary Cause	Underactive thyroid gland	Reduced production in testes/ovaries
Key Symptoms	Fatigue, weight gain, cold intolerance	Fatigue, low libido, muscle loss
Affects Both Men & Women?	Yes	Yes
Common in Women	Irregular periods, infertility, mood swings	Low libido, bone loss, depression
Common in Men	Slowed metabolism, depression	Erectile dysfunction, infertility
Diagnosis	TSH, T3, T4, antibody tests	Total & free testosterone

Conclusion

So, does hypothyroidism cause low testosterone? The answer is yes—low thyroid function can disrupt hormone signaling and lower testosterone in both men and women. This overlap often explains why patients experience fatigue, low libido, mood swings, and fertility challenges.

The good news is that with proper diagnosis and treatment—whether through thyroid hormone replacement, testosterone therapy, or lifestyle improvements—most people can restore balance and reclaim their energy.

If you live in NYC or across the USA and suspect your symptoms may be tied to hormone imbalances, don’t wait. Schedule a consultation with a hormone specialist at TRT NYC to explore testing and treatment options. With the right care, you can take control of your thyroid, testosterone, and overall well-being.

FAQs: Does Hypothyroidism Cause Low Testosterone?

1. Can a low thyroid count really affect testosterone production?

Yes. Hypothyroidism disrupts the pituitary gland and hormone signaling, often lowering testosterone production.

2. What are the low thyroid symptoms in women that overlap with testosterone deficiency?

Fatigue, mood changes, weight gain, and reduced libido are common overlaps.

3. How do I know if my symptoms of hypothyroidism are linked to low testosterone?

The only way to know is through testing—TSH, T3, T4 for thyroid, and total/free testosterone levels.

4. Can treating hypothyroidism restore testosterone naturally?

Often yes. For many men and women, correcting thyroid function improves testosterone without TRT.

5. Is testosterone replacement safe for people with thyroid issues?

Generally, yes — but it should be carefully monitored by a doctor who understands the interplay between thyroid and testosterone therapies.