Early identification of risk factors for refractory secondary hyperparathyroidism in patients with long-term renal replacement therapy.

BACKGROUND: Secondary hyperparathyroidism can complicate renal replacement therapy (RRT) in patients with end-stage renal disease. Current medical therapies often result in hypercalcaemia and fail to correct hyperparathyroidism, but might be more effective at an early stage of disease. The aim of this study was to identify prognostic factors at the start and during the first year of RRT for refractory secondary hyperparathyroidism needing parathyroidectomy (PTx) during long-term follow-up. METHODS: A total of 202 consecutive patients starting RRT between August 1988 and August 1996 at our centre with at least 1 year of follow-up were included. Biochemical and treatment data at the start and during the first year of RRT were collected. Univariate and multivariate analyses were used to identify risk factors for PTx during follow-up. RESULTS: Thirty-three patients (16%) needed PTx after 52+/-23 months of RRT. Need for PTx was not different between patients undergoing haemodialysis and peritoneal dialysis, but was associated with parameters reflecting calcium and phosphate control at start and after 1 year of RRT. In a Cox multivariate model, serum parathyroid hormone relative risk (RR): 1.02 per pmol/l; P<0.001], phosphate (RR: 1.107 per 0.1 mmol/l; P = 0.002) and alkaline phosphatase (RR: 1.004 per U/l; P = 0.049) after 1 year of RRT were independently associated with increased risk for PTx. CONCLUSIONS: Failure of control of calcium-phosphate metabolism at the start of and early during RRT is strongly associated with PTx during long-term follow-up. Given the high prevalence of insufficient phosphate control, patients may benefit from aggressive correction of serum phosphate in the pre-dialysis and early dialysis period.