Measurement of seminal LDH-X and transferrin in normal and infertile men.

LDH-X, an isoenzyme of lactate dehydrogenase specific for germinal epithelium activity, has been measured in the seminal plasma of infertile subjects whose infertility had different origins. In the same samples, seminal transferrin, an index of Sertoli cell function, was also measured. In this investigation, seminal LDH-X was not detectable in the vasectomized subjects, in patients with azoospermia due to seminiferous tubular damage, nor in patients who showed a marked decrease in sperm concentration (less than 1 X 10(6)/ml). In oligozoospermic patients (sperm concentration less than 20 X 10(6)/ml) seminal LDH-X levels were reduced to about one-third of those found in normal controls. Seminal LDH-X levels correlated (r = 0.7237) with total sperm count better than seminal transferrin levels (r = 0.5511), while no correlation was found between these two biochemical parameters and sperm motility, viability and morphology. To study their spontaneous variations with time, LDH-X and transferrin were also measured in semen specimens collected monthly from five healthy men, over 1 year. In these samples (N = 60), sperm count variability (43.1%, calculated in terms of the coefficient of variation), was similar to that of LDH-X (40.4%) and higher than for transferrin (23.0%).