Testosterone-Related Exacerbation of a Prolactin-Producing Macroadenoma: Possible Role for Estrogen

Men with PRL-producing macroadenomas often present with hypogonadism and impotence. This report documents exacerbation of a PRL-secreting tumor after two separate 200-mg testosterone enanthate (T) injections despite continued bromocriptine (BRC) therapy. A 37-yr-old man with a 60-mm invasive tumor and a serum PRL level of 13,969 ± 332 ng/ml (mean ± SD) responded to BRC therapy with rapid disappearance of visual field defect, headache, and facial pain as well as decrease in serum PRL to 5,103 ± 1,446 ng/ml. T injection was followed by severe headache, facial pain, and increase in PRL to 13, 471 ng/ml. Visual field deterioration and increased tumor size (height, 40–43 mm) by computed tomography were documented. A relationship between T injection and exacerbation of the prolactinoma was not recognized until after a second T injection 3 months later. After that therapy, baseline PRL increased from 6,900 to 12,995 ng/ml. The hypothesis that T was aromatized to estradiol, directly stimulating lactotrophs, was s...