Abstract
We explored the possibility that the serum bioactive LH (B-LH) response to gonadotropin releasing hormone (GnRH) infusion might provide additional insight into normal and abnormal pubertal maturation. Controls consisted of 24 boys and 10 men; 1 true isosexual precocity (TIP) and 11 hypopituitary (11-53 yr) cases were studied. Maturationa. staging was by AM testosterone (T). B-LH was assayed by rat leydig cell T production, immunoreactive LH (I-LH) by RIA.
Normally the GnRH-induced B-LH was related to maturational stage in a biphasic manner (cubic fit r=0.85): a) stimulated B-LH is minimal in the most immature children (rising only from 23 to 26 ng/ml in the youngest), b) undergoes an initial rise at T = 20-40 ng/dl (p < .05), c) peaks at a T level of 196 ng/dl, and d) then declines modestly (p< .05) as the T level rises further. B-LH was not so closely related to chronologic age, bone age, or Tanner stage. The pubertal peak in LH was not seen in I-LH data, but was in B-LH/I-LH (B/I), a measure of LH biopotency.
The TIP case had elevated basal B-LH, stimulated-B-LH, and B/I, though I-LH was normal. The abnormalities were progestin-suppressible.
Stimulated B-LH corresponded better than I-LH to the maturation achieved by hypogonadotropic men. B-LH responses to GnRH discriminated teenagers with delayed puberty from those with gonadotropin deficiency once T levels exceeded 30 ng/dl.
In summary, the normal biphasic relationship of B-LH reserve to the baseline T level is an improved diagnostic criterion for distinguishing hypogonadotropinism from delayed puberty.
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Rich, B., Rosenfield, R., Moll, G. et al. 442 BIOACTIVE LH PITUITARY RESERVES DURING NORMAL/ABNORMAL MALE PUBERTY. Pediatr Res 15 (Suppl 4), 513 (1981). https://doi.org/10.1203/00006450-198104001-00453
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DOI: https://doi.org/10.1203/00006450-198104001-00453