['An association between female gender and more aggressive patterns of secondary hyper-parathyroidism (sHPTH) has been suggested: an increased incidence of refractory sHPTH seems evident in females; therefore, necessitating parathyroidectomy (PTx).', 'This study aimed to verify the existence of such an association and secondly to evaluate the impact of female gen-der on parathyroid gland histology. Therefore, a retrospective study was conducted on 67 patients who underwent first PTx (either total or subtotal) in our hospital from 1999-2003. Out of these patients, we selected 55 (28 males, 27 females, mean age 50.8 +/- 14.7 SD yrs, dialysis duration 109.2 +/- 62.4 months) in whom all four parathyroid glands were identified and removed. Serum levels of immunoreactive intact parathyroid hormone (iPTH), alkaline phosphatase, calcium and phosphate were determined at the PTx time point. The same pathologist performed the histological studies of the parathyroid glands on seven serial sections of the glands. Gland hyperplasia was classified as (1) exclusively diffuse (EDH) when only diffuse hyperplasia was found in the four glands; (2) exclusively nodular (ENH) when only nodular hyper-plasia was found in the four glands; (3) diffuse/nodular (D/NH), in which the four glands showed varying degrees of evolution towards both nodular and diffuse hyperplasia.', 'EDH was found in 13 patients with a prevalence of males (11/13; 84.6%); ENH was found in 23 patients with a prevalence of females (15/23; 65.2%); D/NH was found in 19 patients with a similar prevalence between females and males (10 females and 9 males). The difference in the male/female prevalence among the three groups was statistically significant (chi2 test, p=0.015). Serum calcium was significantly higher in the ENH group (one-way analysis of variance, p=0.009). No difference was found among the three groups as far as age, dialysis duration, serum levels of iPTH, alkaline phosphatase and phosphate were concerned.'] Do female hemodialysis patients have an increased risk of nodular hyperplasia of parathyroid glands?