Incidence and clinical characteristics of hypoparathyroidism in dialysis patients

The incidence and clinical characteristics of hypoparathyroidism (Hypo) were evaluated in 8188 hemodialysis (HD) and 1207 CAPD patients treated in 65 hospitals or clinics in Japan. Hypo was defined by an intact parathyroid hormone (PTH) level below 160 pg/ml, which corresponded to the low normal limit of intact PTH to maintain a normal osteoblastic surface in 40 bone biopsy specimens of Japanese dialysis patients, and patients were classified into two groups: absolute Hypo (A-Hypo), intact PTH < 60 pg/ml, and relative Hypo (R-Hypo), 60 pg/ml < or = intact PTH < 160 pg/ml. A total of 2537 (31.0%) and 2736 (33.4%) HD patients were classified into A- and R- Hypo, and 401 (31.3%) and 379 (31.4%) CAPD patients occupied A- and R-Hypo, respectively. A high incidence of Hypo was observed in the HD patients with diabetes mellitus (DM) and old age (> or = 70 years old) compared with that of a nationwide epidemiological report for dialysis patients by Japanese Society for Dialysis Therapy. Hypo patients who were treated by CAPD had a background of being younger, having a shorter duration on dialysis, and were less frequently diagnosed with DM than in those Hypo patients on HD. Bone pain and metastatic calcification were observed in approximately 20% and 25% of Hypo patients, respectively. No difference was observed in the background factors and the prevalence of signs and symptoms between the A- and R-Hypo groups, regardless of the mode of treatment (HD or CAPD). These results suggest that a very high incidence and specific backgrounds (DM and aging) of Hypo exist in Japanese dialysis patients.