Your thyroid gland is small structure in the front of your neck, just above your collarbone. Its importance for your health and well-being is far out of proportion to its diminutive size. The thyroid makes hormones that regulate the metabolic rate of your cells in addition to influencing growth and development, and the functions of your cardiovascular, nervous and reproductive systems. When the thyroid is underactive in hypothyroidism or overactive in hyperthyroidism, many bodily functions are affected. Although changes caused by thyroid problems are similar for both sexes, men can experience some symptoms that differ from those in women.
With both hyperthyroidism and hypothyroidism, men might experience fertility problems. When a man has an overactive thyroid, he may produce sperm with poor mobility, also known as low motility. This could interfere with a man's ability to father a child. Thyroid disorder-related changes in sperm are reversed in most cases when treatment brings the thyroid hormones back to normal levels.
Hypothyroidism can also cause fertility problems in men because the condition may lead to overproduction of a pituitary hormone called prolactin. Too much prolactin can lead to a drop in testosterone, a male hormone that supports sperm production. A study published in the winter 2012 issue of the "Urology Journal" found that men with hypothyroidism had low sperm counts that could interfere with conception, compared to men with normal thyroid function. Fertility problems associated with hypothyroidism are often reversible with successful treatment.
Hypothyroidism and hyperthyroidism can affect sexual function in men, according to a study published in the December 2005 issue of the "Journal of Clinical Endocrinology and Metabolism." Among a group of 34 men with hyperthyroidism, 50 percent experienced premature ejaculation and about 15 percent had erectile dysfunction that interfered with their ability to maintain an erection. Among a group of 14 men with hypothyroidism, about 65 percent had erectile dysfunction, delayed ejaculation and low libido, or poor sex drive. Although the exact mechanisms by which abnormal thyroid hormone levels affect male sexual function are not fully understood, these symptoms improved in many of the men in both study groups when their thyroid problems were treated.
In addition to problems affecting male reproductive function, men with thyroid problems often experience non-reproductive symptoms that also commonly occur in women with thyroid disorders. When thyroid hormone levels are too high, a man may feel uncomfortably warm or sweat excessively at normal room temperature. Weight loss may occur despite no change in diet or eating more than usual. Loose stools, nervousness, anxiety, jitteriness and trembling of the hands are also common. The heart rate is often fast and commonly perceived as pounding or fluttering in the chest.
A man with hypothyroidism may feel unusually cold, even when outside in warm weather or indoors at normal room temperature. Other possible symptoms include lack of energy, weakness, fatigue, constipation, depression, mental sluggishness and muscle aches. Weight gain frequently occurs despite no change in diet.
Other Considerations, Next Steps and Precautions
Hypothyroidism and hyperthyroidism are considerably more common in women than men, as is thyroid cancer. Hyperthyroidism occurs in only 0.2 percent of men, compared to about 2 percent of women. Hypothyroidism occurs in 4 to 5 women per 1,000, but only 0.6 to 0.9 men per 1,000. Approximately 75 percent of thyroid cancers occur in women, reports the American Cancer Society.
See your doctor if you experience problems with erectile function or ejaculation, or note any other symptoms that might indicate a thyroid problem. Blood tests can determine whether your thyroid hormone levels are normal, depressed or elevated. Consult with your doctor as right away if you notice any warning signs or symptoms that might suggest thyroid cancer, including:
-- a lump at the front of your neck
-- difficulty swallowing or breathing
-- hoarseness or a change in your voice
-- frontal neck pain
Reviewed and revised by: Tina M. St. John, M.D.