Conversely, men with microprolactinoma showed a significant increase in hematocrit (HCT) and hemoglobin (Hb) levels after PRL normalization (median HCT 42.3 vs.44.0%; Hb 14.5 vs. 15.1 g/dL; both p < 0.005). The gene discussed is GSTM1; the disease is Microprolactinoma.