Seminal transferrin, an index of Sertoli cell function: is it of clinical value?

To determine the clinical value of seminal transferrin measurements, transferrin concentrations in seminal plasma were determined by single radial immunodiffusion. Men with various disorders of spermatogenesis had significantly lower mean values than those with normal semen (170 micrograms/ejaculate, s.e.m. = 18.4), oligospermia (40.5 micrograms, s.e.m. = 7.2) or azoospermia due to primary seminiferous tubule failure (65.9 micrograms, s.e.m. = 29.1). In these subjects with patent genital tracts, seminal transferrin was directly correlated with sperm concentration and indirectly correlated with serum FSH levels. Seminal transferrin increased following gonadotrophin treatment of men with gonadotrophin deficiency from 19.6 micrograms (s.e.m. = 5.5) to 108.6 micrograms (s.e.m. = 31.7). Patients with genital tract obstructions also had low levels; vasal agenesis (21.8 micrograms, s.e.m. = 5.6), vasectomy (48.5 micrograms, s.e.m. = 21.0), epididymal obstruction (46.6 micrograms, s.e.m. = 7.1). These results confirm that most seminal transferrin comes from the testes and reflects Sertoli cell function. However, there is a very wide range of transferrin levels in normal semen and a number of normospermic samples have low values similar to those seen with abnormal Sertoli cell function or obstruction. Thus, measurement of seminal transferrin is of limited diagnostic value.