Background: The Dialysis Outcomes and Practice Patterns Study (DOPPS) reported high incidence of depression in haemodialysis patients. Hypercalcaemia and high parathyroid hormone (PTH) levels are aetiological factors of psychological disorders. We examined the association between mineral metabolism abnormalities and mental health in Japanese-DOPPS patients.
Methods: We used baseline data of Japan-DOPPS, Phase 1 (2755 patients, 1999-2001) and Phase 2 (2286 patients, 2002-03). The outcome variable was mental health using the mental health domain of SF-36. We examined the association between serum corrected calcium, phosphorus, calcium x phosphorus product and intact PTH concentrations, and mental health using analysis of covariance and also the associations between corrected calcium levels and current use of vitamin D and calcium-containing phosphate binder.
Results: There was a significant association between mental health and corrected calcium levels. A significantly lower mental health score was noted in patients with corrected calcium > or = 11 mg/dl than in <8.4 (P = 0.04), > or =8.4 to <10.2 (P = 0.009) and > or =10.2 to <11 mg/dl (P = 0.003). The association was significant even after adjustment for age, sex and other confounders. However, there was no relationship between intact PTH and mental health. High-corrected calcium levels were significantly associated with the use of intravenous active vitamin D and calcium-containing phosphate binder.
Conclusions: Hypercalcaemia, but not high intact PTH, is associated with poor mental health in dialysis patients. While a cause-effect relationship between hypercalcaemia and deterioration of mental health needs further confirmation by longitudinal and prospective studies, our observational findings suggest the importance of control of serum calcium concentration in dialysis patients.