Thyroid Hormone Disorders
// October 29th, 2010 // No Comments » // Hormones
The thyroid hormone thyroxine stabilizes the body’s metabolism and allows us to proceed on an even keel from day to day. Both excessive and inadequate thyroxine production (hyperthyroidism and hypothyroidism) can interfere with normal male sexual function.
The diagnosis of thyroid hormone disorders is usually not difficult in young men. Nervousness, palpitations, weight loss, tremor, and anxiety are manifestations of excessive thyroid hormone secretion. Fatigue, lethargy, slowness of thought, constipation, dry skin, cold intolerance, and a deepening voice are indications of hypothyroidism.
In the older man, symptoms are more subtle. An irregular heartbeat or unexplained weight loss may be a clue to an overactive thyroid. Memory loss can reflect inadequate thyroid production. In the middle-aged or older male, impotence may be the only obvious evidence of either condition.
Daniel, a fifty-two-year-old scientist, became impotent shortly after his divorce. His impotence was thought to be related to depression, and he had been seeing a psychiatrist for about one year. He had made some progress coping with his postdivorce depression, but his impotence persisted. Now he had a new problem — his left breast seemed to be growing.
Physical examination revealed a rapid pulse and a slightly enlarged thyroid. Daniel’s’ left breast was indeed large and glandular. His hands trembled. The thyroid enlargement, increased breast size, rapid pulse, and tremor suggested the possibility of an overactive thyroid. Blood tests provided confirmation. With treatment, thyroid hormone levels normalized, breast tissue receded, and potency was restored.
Disorders of thyroid function are generally not considered in the evaluation of impotence despite the fact that loss of libido (in about 70 percent of cases), impotence (in about 55 percent of cases), and breast enlargement (incidence unknown) are prominent in hyperthyroid men. It remains unclear exactly how hyperthyroidism predisposes men to these sexual problems. The hyperthyroid state does create several associated hormonal abnormalities. Testosterone production is adequate, but the body converts an inordinate amount of the testosterone into an estrogen hormone (estradiol). Correction of the hyperthyroidism diminishes the stimulus for excessive estrogen production and coincides with a return of libido and potency.
Men with underactive thyroids tend to have low serum testosterone levels. Correction of the hypothyroidism usually allows serum testosterone levels to return to normal, and sexual function resumes. Unfortunately, some hypothyroid patients experience failure of both thyroid and testicular hormone secretion. For those men, treatment with thyroid hormone and testosterone together is necessary to restore metabolic, and then sexual, health.
Men with hypothyroidism have one other hormone abnormality that contributes to their sexual dysfunction. Their serum prolactin levels are often elevated. For them, bromocriptine treatment is unnecessary; thyroid hormone alone will normalize prolactin levels. Once prolactin levels normalize, sexual function resumes.
