Lack of Specificity of Plasma Concentrations of Inhibin B and Follicle-Stimulating Hormone for Identification of Azoospermic Survivors of Childhood Cancer: A Report From the St Jude Lifetime Cohort Study

Purpose Many male survivors of childhood cancer are at risk for azoospermia. Although both the levels of follicle-stimulating hormone (FSH) and inhibin B are correlated with sperm concentration, their ability to predict azoospermia in survivors of childhood cancer remains uncertain.Patients and Methods Semen analysis was performed and serum levels of FSH and inhibin B were measured in 275 adult male survivors of childhood cancer who had received gonadotoxic therapy. Receiver operating characteristic (ROC) analysis was performed to determine the optimal inhibin B and FSH values for identifying patients with azoospermia. The patient sample was divided into a learning set and a validation set. Sensitivity, specificity, and positive and negative predictive value were calculated.Results Inhibin B was dichotomized as ≤ 31 ng/L or more than 31 ng/L and FSH was dichotomized as ≤ 11.5 mIU/mL or more than 11.5 mIU/mL based on results of the ROC analysis. Using these values, the specificity of the serum level of inhibin B for identifying azoospermic survivors was 45.0%, and the positive predictive value was 52.1%. The specificity for FSH was 74.1%, and the positive predictive value was 65.1%.Conclusion Neither serum inhibin B nor FSH is a suitable surrogate for determination of sperm concentration in a semen sample. Young men and their physicians should be aware of the limitations of these measures for assessment of fertility potential.