Luteinizing hormone pulsatility in men with damage to the germinal epithelium

Abstract

Bioactive‐LH (B‐LH) was measured in plasma by in‐vitro bioassay and immunoactive‐LH (I‐LH) by immunoassay at 10 min intervals for 6 h in five men after standard chemotherapy for Hodgkin's disease. Eleven normal men acted as controls. Follicle‐stimulating hormone (FSH) was markedly raised in the treated patients (mean ± SEM; 12.8 ± 2.8 vs. 2.7 ± 0.4 IU 1‐1, P >0.006) reflecting damage to the germinal epithelium. Bioactive (27.4 ± 2.8 vs. 12.9 ± 1.3 IU 1‐1) and I‐LH (9.6 ± 2.0 vs. 4.9 ± 0.4 IU 1‐1) were elevated (P>0.006) in the patient group whilst testosterone levels (24.0 3.8 vs. 19.6 2.4 nmol 1‐1) were normal. The testosterone I‐LH ratio, a putative index of Leydig cell dysfunction, was negatively correlated with FSH levels (r=‐0.85, P >0.02). Bioactive and I‐LH pulse peak amplitude were elevated, as were pulse maxima (P>0.05). In contrast, B‐LH pulse frequency was similar between the patients (2 pulses per 6 h) and controls (median 2, range 1–3 pulses per 6 h) as was the I‐LH pulse frequency (median 2, 1–2 pulses per 6 h in both groups). The mean B:I LH ratios were similar (2.94 ± 0.09 vs. 2.63 ± 0.14) in both groups, although the inter‐pulse B:I ratio was increased (P>0.007) in the patient group. It is concluded that normal levels of testosterone are maintained in men with chemotherapy‐induced damage to the germinal epithelium by a resetting of the hypothalamic‐pituitary unit such that LH pulse amplitude but not the pulse frequency is increased markedly. The mean biopotency of LH remained unchanged although the inter‐pulse B:I LH was increased. Copyright © 1990, Wiley Blackwell. All rights reserved