Low serum inhibin B levels as a marker of testicular damage after treatment for a childhood malignancy

The aim of this study was to evaluate the role of inhibin B and the determination of its concentration to diagnose testicular damage after treatment for a childhood malignancy. Thirty-seven males treated for Hodgkin disease (n = 11) or non-Hodgkin lymphoma (n = 26) were examined at a mean age of 16.9 +/- 2.9 years. Mean age at the stop of therapy was 11.3 +/- 3.0 years and in most cases the chemotherapy regimen included gonadal damaging alkylating agents. Thirty-three normal males (mean age 17.9 +/- 4.1 years) were examined as controls. Serum samples were collected for determination of inhibin B, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone. Median inhibin values were significantly lower in patients than in controls (96.0 vs 225.0 pg/ml, P < 0.0001) and a strong negative correlation was found between inhibin B and FSH (r = -0.86, P < 0.0001), a weak correlation with LH (r = -0.32, P < 0.05) and no correlation with testosterone. In post-pubertal patients (i.e., over 16 years) a positive correlation was found between testicular size and inhibin level (r = 0.53, P < 0.05), but not between testicular size and testosterone level. Pathological low levels (values that differed by more than 2 SD from the mean value of control subjects) were found in 20 patients for inhibin B and 8 for testosterone (P < 0.01) and pathological high values in 19 patients for FSH and 3 for LH. Conclusion This study confirms the role that inhibin B plays in the regulation of FSH secretion and provides further evidence of the utility of its evaluation as a direct indicator of male gonadal dysfunction.