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Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
 
 
 
 
 

Single versus repeated dose human chorionic gonadotropin stimulation in the differential diagnosis of hypogonadotropic hypogonadism.

The responses of serum testosterone ( T), 17 alpha-hydroxyprogesterone, and 17 beta-estradiol (E2) to four im injections of hCG (5000 IU/1.7 m2) given on days 0, 4, 7, and 10 were studied in 10 prepubertal and 10 pubertal boys with hypogonadotropic hypogonadism (groups O and P, respectively). Serum was obtained before each injection and on day 14. The results were compared with those of controls, 16 prepubertal boys with incomplete testicular descent and 6 pubertal boys with constitutional delay of puberty. Serum T levels increased significantly in groups O and P to 2.0 and 4.6 nmol/liter, respectively, after the first injection, then progressively to 5.8 and 11.2 nmol/liter. Basal T levels of group O did not differ from those of the controls, but were subnormal for group P (P less than 0.001). Stimulated T levels were subnormal in both groups (P less than 0.01 and P less than 0.001), but repeated doses increased the difference from the control value only in group P. A difference in E2 response between patients and controls appeared in puberty; only the pubertal control boys had substantial increases in E2 (P less than 0.001). Our results show that the optimal protocol for a diagnostic hCG test in prepubertal boys is a single dose of hCG, with determination of T levels 4 days later. In puberty, if the basal T levels are inconclusive, repeated doses of hCG should be given with determination of both T and E2. These findings also suggest that the full inhibitory effect of E2 on T synthesis results from a pubertal maturation process, possibly induced by endogenous gonadotropins, which cannot be induced by two weeks of hCG stimulation in prepubertal boys or those with hypogonadotropic hypogonadism.[1]

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