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Testosterone is men's primary sex hormone and anabolic steroid, serving an essential role in male development. While we strongly associate testosterone with men, it is also present in females, and both sexes can experience problems when testosterone levels are low. Here we look at how hypothyroidism, the most common thyroid disease, can affect testosterone levels.
Hypothyroidism is a disease state where the thyroid gland does not produce enough thyroid hormone to support metabolic processes in the body. The thyroid gland is located at the nape of the neck and is an endocrine gland because its primary job is to make and secrete hormones.
When a person has hypothyroidism, they struggle with symptoms related to insufficient cellular energy.
Common symptoms of hypothyroidism include:
- Fatigue and lethargy
- Cold intolerance
- Muscle aches and joint pain
- Slow heartbeat
- Sexual dysfunction
Several factors can cause hypothyroidism in a person.
Sometimes, the immune system, meant to protect the body from invading infections, mistakes the thyroid gland as foreign and attacks. If there is enough damage, the thyroid gland can no longer make enough thyroid hormone, causing hypothyroidism.
Surgical removal of part or all of the thyroid gland
People with thyroid nodules, thyroid cancer, or Graves' disease may need to have part or all of their thyroid removed, causing hypothyroidism. If the gland is only partially removed, the body may still be able to make enough thyroid hormone on its own.
People with Graves' disease, nodular goiter, or thyroid cancer may be treated with radioactive iodine to destroy the thyroid gland. Radiation treatment may also be used on patients with Hodgkin's disease, lymphoma, or cancers of the head or neck. These patients may lose part or all of their thyroid function, causing hypothyroidism.
Congenital hypothyroidism is a partial or complete loss of function of the thyroid gland that affects infants from birth. Congenital hypothyroidism is caused by the baby not getting enough iodine in the womb or thyroid gland damage or malformation.
Medicines like amiodarone, lithium, interferon-alpha, and interleukin-2 can prevent the thyroid gland from being able to produce hormones. These drugs may trigger hypothyroidism in patients with a genetic predisposition to autoimmune thyroid disease.
Too much or too little iodine
The thyroid gland needs iodine from food to produce thyroid hormones. However, taking too much iodine can cause or worsen hypothyroidism. Iodine deficiency is not typically an issue in the United States due to the iodization of salt.
Damage to the pituitary gland
The pituitary gland (or the "master gland") instructs the thyroid on how much hormone to make. The pituitary gland may no longer be able to communicate correctly with the thyroid gland if it is damaged by a tumor, radiation, or surgery, possibly leading to hypothyroidism.
Testosterone is made primarily in the gonads (ovaries in women and testes in men), but the adrenal glands also produce a small amount. All three of these organs are receptive to thyroid hormone levels.
Hypothyroidism can lower free testosterone in the body. Indeed, low thyroid hormone can throw off the balance of many other hormones related to testosterone, including luteinizing hormone (LH) and follicle-stimulating hormone (FSH). When a person has hypothyroidism, it can cause LH and FSH to increase, especially in men.
Testosterone levels can fall in hypothyroidism because sex-hormone binding globulin (SHBG) decreases when thyroid activity is low. SHBG is a protein made by the liver that binds to testosterone, dihydrotestosterone (DHT), and estrogen. Essentially, its role is to determine how much of these hormones should be delivered to tissues in the body.
On the contrary, when a person has hyperthyroidism, it can cause an increase in total serum testosterone levels because SHBG increases. Incidentally, because of the increase in SHBG, estradiol has also been found to increase in men, which can cause gynecomastia, decreased libido, and spider angiomas.
Most studies on testosterone and thyroid hormone focus on men, so we know more about how this relationship can affect men over women. And surprisingly, many of the symptoms related to low testosterone are also common in hypothyroidism.
Signs of low testosterone in men include:
- Decreased sexual function, including low sexual desire
- Erectile dysfunction
- Loss of muscle mass
- Weight gain
- Hair loss
When it comes to low testosterone in women, we know much less, as there has been little research on how lower levels of testosterone impact women. However, testosterone levels appear to drop significantly with age in women, and they likely decrease by half once a woman reaches perimenopause.
Many of the symptoms of low testosterone in women are similar to those in men and include:
- Low libido
- Depressed mood
- Increased sexual responsiveness
- Muscle weakness
If you have hypothyroidism and are concerned about your testosterone levels, there is some promising news: treating hypothyroidism often corrects low testosterone levels. Hypothyroidism is relatively easy to treat, as it usually requires a person to take daily thyroid hormone medication to keep thyroid levels stable.
You will need a complete thyroid function test that includes TSH, free T3, free T4, and TPO antibodies. The last marker, TPO antibodies, is essential for assessing if you have Hashimoto's disease. If your lab results indicate thyroid disease, your thyroid doctor can prescribe thyroid hormone replacement medication that will likely resolve most symptoms related to low testosterone.
Testosterone replacement therapy is still being researched and is most commonly used to treat primary hypogonadism, a condition where the testes cannot produce enough testosterone. However, many clinics promote testosterone replacement therapy to combat signs and symptoms of aging. While there is anecdotal evidence of people saying they feel better and more energized when taking testosterone in the form of gels, patches, or pills, there is little research to back up these claims.
What is more, testosterone therapy used outside of treating hypogonadism can cause or worsen certain health conditions, including sleep apnea, acne, benign and cancerous growth of the prostate, and fertility.
To start feeling better, take an at-home thyroid blood test to determine if a thyroid disorder is behind your symptoms. A top thyroid doctor from Paloma Health can help you interpret your lab results and create a personalized thyroid treatment plan to help you get back on track.