Prevalence of secondary hyperparathyroidism in patients with stage 3 and 4 chronic kidney disease seen in internal medicine

Objective: Despite the high prevalence of chronic kidney disease in the elderly population, few data are available on the frequency of secondary hyperparathyroidism in the Spanish population affected by this problem. We undertook a study on this issue in patients attending the internal medicine departments in our area. Design and methods: An observational, cross-sectional survey performed at internal medicine departments on 415 patients with stage 3 and 4 chronic kidney disease. Clinical history and risk factors were collected using a standardized protocol. Serum creatinine, phosphate, calcium, intact parathormone (PIN) and 25-hydroxy-cholecalciferol (25-OH-vitD) levels were measured in all patients. Results: Among stage 3 patients, 62.9% had PTH levels >= 70 pg/mL and 32.7% levels >= 110 pg/mL. Median PTH level in stage 4 patients was 120 pg/mL (p < 0.001), and 77.9% of these patients had PTH >= 70 pg/mL (p < 0.001) and 54.1% >= 110 pg/mL (p = 0.015). Adequate 25-hydroxy-cholecalciferol levels were found in only 7.2% of stage 3 patients and 4.1% of stage 4 patients. Only 7.2% of stage 3 patients had hyperphosphatemia, as compared to 25.4% of stage 4 patients (p < 0.001). Conclusions: Hyperparathyroidism is a common complication of stage 3 and 4 chronic kidney disease which is not associated to detectable changes in serum calcium and phosphate levels. It is therefore advisable to measure PIN levels in all patients with decreased glomerular filtration rate. (C) 2015 SEEN. Published by Elsevier Espana, S.L.U. All rights reserved.