The aim of this study was to examine the hypothesis that decreased
LHRH pulse frequency may be responsible for the preferential rise in FSH in infertile men. The LH pulse pattern was determined as an index of hypothalamic
LHRH secretion in 21 infertile patients with idiopathic
azoospermia or oligoasthenozoospermia and 14 fertile age-matched controls by frequent blood sampling at 10-min intervals for 24 h. The infertile patients were further divided into three groups according to their relative concentrations of FSH and
LH: (1) normal FSH and LH, (2) raised FSH but normal LH, and (3) raised FSH and LH. LH pulses were detected by a computerized algorithm (Munro) validated against a threshold method. Concentrations of FSH,
testosterone,
sex hormone-binding globulin and
oestradiol were measured in pooled plasma.
Luteinizing hormone pulse frequencies in normal men were not significantly different from the infertile group as a whole. Similarly, mean LH pulse frequencies in infertile subgroups 1, 2 and 3 were not significantly lower than normal. Pulse interval, however, was increased in subgroup 1 compared with normal. Mean 24 h LH in group 2 was significantly higher than normal, but still within the normal range. The total
testosterone, but not the free
testosterone index was significantly decreased in the infertile group compared with normal. There was no correlation between mean FSH and LH pulse frequency or interval. In conclusion, our results show that in patients with seminiferous tubular dysfunction, the typical pattern of raised plasma FSH, increased LH pulse amplitude, raised FSH: LH ratio and normal or marginally low
testosterone was not associated with any significant deviations in
LHRH pulse frequency from the range observed in normal fertile men. This is not compatible with the hypothesis that decreased
LHRH pulse frequency is associated with or the cause of the preferential rise in FSH in men with idiopathic
infertility. Thus unlike anovulatory
infertility in females, functional defects of hypothalamic
LHRH secretion remain an uncommon finding in
male infertility. Attempts to treat idiopathic
oligozoospermia by altering
LHRH pulse frequency is therefore unlikely to yield any clinical benefit.