Robert M. Blizzard

We undertook a study of the separate and combined effects of age and sex on the pulsatile pattern of GH secretion. The 24-h secretory profile of GH was generated by 20-min sampling in 10 young women (aged 18-33 yr), 10 young men (aged 18-33 yr), 8 postmenopausal women (aged greater than 55 yr), and 8 older men (aged greater than 55 yr). A computer-assisted pulse analysis program was used to assess both total GH secretion, as reflected in the 24-h integrated GH concentration (IGHC), and pulsatile secretion, as denoted by pulse frequency, duration, amplitude, and the fraction of GH secreted in pulses during the 24-h period (FGHP). IGHC was significantly greater in women than in men (P less than 0.025) and greater in the young than in the old (P less than 0.003). The mean pulse amplitude, duration, and FGHP were each greater in the young (P less than 0.006, P less than 0.03, and P less than 0.0001, respectively), but not significantly different between the sexes. The mean pulse frequency was not affected by sex or age. The serum concentration of free estradiol, but not free testosterone, correlated with IGHC (r = 0.46; P less than 0.005), pulse amplitude (r = 0.53; P less than 0.001), and FGHP (r = 0.59; P less than 0.0002). After correcting for the effects of estradiol, neither sex nor age influenced IGHC or mean pulse amplitude, while the effect of age on FGHP was reduced from 81% to 29%. Of the indices of GH secretion, FGHP had the strongest correlation (r = 0.43; P less than 0.006) with somatomedin-C. Somatomedin-C declined significantly with age in both sexes. Our results indicate that sex and age have independent and interrelated effects on GH secretion. These effects can be largely accounted for by corresponding variations in endogenous estradiol levels. These observations suggest an amplifying action of estradiol on the neuroendocrine regulation of pulsatile GH release.

A review of 295 patients with autoimmune Addison's disease which occurred as part of a polyglandular autoimmune syndrome is presented. Information of 41 cases was obtained from our clinics and from the examination of medical records, while 254 cases were culled from the literature. We report that autoimmune Addison's disease in association with other autoimmune diseases occurs in at least two distinct types. Addison's disease occurring in Type I polyglandular autoimmune disease (PGA) is associated with chronic mucocutaneous candidiasis and/or acquired hypoparathyroidism. The age of onset is predominately in childhood or in the early adult years. Type I PGA syndrome is also frequently associated with chronic active hepatitis, malabsorption, juvenile onset pernicious anemia, alopecia and primary hypogonadism. Insulin requiring diabetes and/or autoimmune thyroid disease are infrequent. In contrast, Addison's disease in Type II PGA is associated with insulin requiring diabetes and/or autoimmune thyroid disease(s). Although the age of onset of Addison's disease in Type II PGA syndrome is not confined to any age group or any specific sex, it occurs predominately in the middle years of life in females. The associated autoimmune diseases found in Type I disease, such as chronic active hepatitis, etc. (see table II) are rare in Type II PGA disease except for a low frequency of gonadal failure. We provide evidence to support the concept that the Addison's diseases in Type I and II PGA syndromes have different genetic bases, as related to HLA haplotypes, and possibly have different underlying pathogeneses.