German Lizarralde

Combined deficits in the somatotropic and gonadotropic axes in healthy aging men: An appraisal of neuroendocrine mechanisms by deconvolution analysis

We have employed deconvolution analysis of 24-h serum GH, LH, and FSH concentration profiles to evaluate the nature of age-associated changes in GH, LH, and FSH secretion and disappearance in healthy older individuals. Our findings indicate that healthy aging results in a diminished frequency of detectable GH secretory episodes and an apparent decrease in estimated GH half life in men. These combined effects lead to a significant reduction in mean serum GH concentrations over 24 h. In contrast, we find that LH secretory burst frequency tends to increase with a reciprocal decrease in amplitude as serum total and free testosterone concentrations decline during healthy aging. There is also a prolongation of LH secretory burst duration, and a putative increase in basal LH secretion rates. The changes in LH secretory dynamics are specific, because the half life of immunoradiometric LH and the mass of hormone secreted per burst are not altered. In contrast, the apparent half life of FSH increases with age, and the secretory burst duration may decrease. This spectrum of distinct neuroendocrine sequelae of aging has interesting implications to both investigative and therapeutic strategies for modifying the somatotropic and gonadotropic axes in aging individuals.

Amenorrhea and edema.

In a 22 year old woman extensive edema developed during evaluation for amenorrhea. It was learned then that she was consuming escessive amounts of a laxative daily. Balance studies were performed which demonstrated that she excreted large amounts of sodium in her liquid stools while taking the dose of laxative she had been using. The presence of increased plasma renin activity and increased urinary aldosterone suggest that in this patient the occurrence of the edema after she discontinued use of the laxative was due to secondary aldosteronism presumably caused by plasma volume depletion.