Both hyper- and hypogonadotropic hypogonadism occur transiently in acute illness: bio- and immunoactive gonadotropins.

Previous reports of hypogonadotropic hypogonadism in critically ill men may not reflect the complexity of changes in the hypothalamic-pituitary-gonadal (HPG) axis during acute illness. We sampled blood throughout hospitalization in 55 men admitted to acute care units to delineate the spectrum of changes in circulating gonadotropin and sex steroid levels at the onset and during recovery from acute illness. Bioactive LH and FSH were measured in a subset of patients. Percent free testosterone was measured to assess changes in binding to sex hormone binding globulin. Medications and serum estrogen and prolactin levels were monitored as potential causes of hypogonadotropism. Sustained suppression of serum testosterone levels below the normal range occurred in 62% of men with varying diagnoses and disease severity. Percent free testosterone remained constant. Hypogonadotropism was observed in most men (60%) and occurred independently from head injury, surgery, medications, or hyperprolactinemia. In a subset of men (n = 16), LH and/or FSH rose transiently above the normal range. Bioactivity of both LH and FSH remained constant while serum testosterone levels decreased. In contrast to serum testosterone levels, mean serum levels of E1, E2 and androstenedione were not less than control values. We conclude that both primary and secondary hypogonadism occur transiently in acutely ill men and cannot be explained solely by medications, hyperprolactinemia, or hyperestrogenemia. Neither biopotency of gonadotropins nor binding of testosterone to SHBG change across the course of acute illness. The hypogonadism, often severe and prolonged, may contribute to the persistent catabolic state observed in many critically ill patients.