Free l-carnitine in human semen.

Abstract

Spectrophotometrical (412 nm) readings of known amounts of 1-carnitine gave absorbancy changes with minimal interassay variations (8%) in the range of 15.6-125 microM. A 100-microliters volume of seminal plasma was needed for optimal assay repeatability; recoveries of added carnitine were linear (r = 0.998), indicating a sensitivity limit of 0.70 microgram/ml. Intraassay and interassay repeatability gave variation coefficients of 2% and 1.2%, respectively. By this method, 20 samples in duplicate were analyzed within 2 h. Carnitine levels and semen volumes were inversely correlated (r = 0.49). The ejaculated amounts of carnitine (microgram/ejaculate) were not significantly different in 16 normozoospermic subjects and in 13 oligozoospermic patients. Undetectable levels of carnitine were found in case of deferential-vesicular agenesis, and very low levels were found in cases of monorchidism, confirming the epididymides as major producing organs of the substance. Very low levels were also found in semen of men with varicocele, suggesting that seminal carnitine would be regarded as an index of androgenization.