Anemia, testosterone, and pituitary adenoma in men

Older men with clinically nonfunctioning pituitary tumors have been noted to be anemic, to have hypopituitarism, and to have low serum levels of testosterone. The authors hypothesized that men with pituitary adenomas and hypogonadism have a physiologically related decrease in hematocrit.

A retrospective analysis was conducted of 216 patients older than 50 years of age who harbored pituitary adenomas. In 100 men serum testosterone levels and a complete blood (cell) count (CBC) were obtained before treatment; a CBC was also acquired in a series of women with pituitary adenomas. Using clinical laboratory standards, anemia was defined as a hematocrit less than 40% in men and less than 35% in women. Thirty-one (46.3%) of 67 men with low serum concentrations of testosterone were anemic. In men with low levels of testosterone, the average hematocrit was 39.9%, compared with 45.6% for men with normal testosterone levels (p < 0.001). Men with macroadenomas were most likely to have both anemia and a low serum concentration of testosterone. Anemia was associated with a low level of testosterone, adjusting for tumor size (odds ratio 19, 95% confidence interval 4.86-77.03). Of patients with anemia, 84% were men and 16% were women (p < 0.001). The prevalence of anemia in women was low and was not correlated with tumor size. Men receiving testosterone replacement therapy had a significantly higher hematocrit value than men with low or normal testosterone levels.

These findings support a direct relationship between serum testosterone levels and hematopoiesis in men, and demonstrate that hematopoiesis is compromised in men who have low concentrations of testosterone due to a pituitary adenoma.