Association of low prostate-specific antigen concentration and panhypopituitarism

Objective: To report the association of undetectable or very low prostate-specific antigen (PSA) concentrations with hypopituitarism. Methods: We present a case series of 4 patients with low or undetectable PSA concentrations and associated panhypopituitarism and summarize the clinical presentation and pertinent laboratory and radiologic findings. We review related literature and discuss possible mechanisms explaining the described association. Results: Four men with PSA values below the second percentile of a healthy population had hypopituitarism. In 3 men, low PSA concentrations were noted before large pituitary tumors were diagnosed. No man had headaches, visual problems, or other symptoms that were severe enough to prompt a search for tumor. All 4 patients had undetectable total testosterone levels. Luteinizing hormone and follicle-stimulating hormone levels were low to low-normal in 3 of the 4 patients. Baseline growth hormone level was low in 1 patient and undetectable in the other 3. The insulinlike growth factor 1 concentration was less than 73 ng/mL in each patient. Conclusions: We believe that the association of low PSA concentrations and hypopituitarism is not incidental and that the extremely low PSA values in this case series were a consequence of both gonadal and growth hormone deficiency. We suggest that low PSA is a marker of combined profound testosterone and growth hormone deficiency in men with panhypopituitarism. This marker is important because PSA is frequently measured during routine health care visits; a low concentration may be the first clue to the presence of hypopituitarism in an otherwise asymptomatic patient.