Vitamin D receptor genotype influences parathyroid hormone and calcitriol levels in predialysis patients

Autor: Mercè Borràs, Elvira Fernández, Joan Fibla, Jaume Almirall, M. L. Amoedo, Isabel Martínez, R. Saracho, Maria Paz Marco
Rok vydání: 1999
Předmět:
Zdroj: Kidney International. 56(4):1349-1353
ISSN: 0085-2538
DOI: 10.1046/j.1523-1755.1999.00678.x
Popis: Vitamin D receptor genotype influences PTH and calcitriol levels in predialysis patients. Background BsmI vitamin D receptor (VDR) gene polymorphism has been associated with the severity of hyperparathyroidism in patients on hemodialysis. The aim of this study was to analyze the influence of this polymorphism on parathyroid function and serum calcitriol levels in patients with different degrees of chronic renal failure (CRF) before dialysis. Methods A total of 248 CRF patients, divided into three groups according to creatinine clearance (C Cr ; mild CRF group> 60 to ≤85 ml/min, N = 54; moderate CRF group> 35 to ≤60 ml/min, N = 113; severe CRF group> 10 to ≤35 ml/min, N = 81), had their serum intact parathyroid hormone (iPTH) and calcitriol levels measured and Bsm I genotype frequencies estimated by polymerase chain reaction (PCR) analysis. Diabetics, those on treatment with steroids, vitamin D or derivatives, and phosphorus binding agents were excluded. All those with serum calcium levels of 2.5 mmol/liter and serum phosphorus levels openface> 1.6 mmol/liter or who needed phosphorus binding agents were excluded. The statistical analysis was done with the general factorial analysis of variance entering first PTH and then calcitriol as the dependent variable; the genotype (BB, Bb and bb), sex and C Cr group were defined as factors; and covariables included serum calcium, serum phosphorus, 1/creatinine versus time slope, PTH when calcitriol was the dependent variable, and calcitriol when PTH was the dependent variable. Results When serum PTH levels were entered as the dependent variable, serum calcium, C Cr group, and the interaction of genotype with the C Cr group were found to be significant factors ( P = 0.025, P P = 0.039, respectively). When serum calcitriol levels were entered as the dependent variable, genotype, the interaction of genotype with C Cr , the C Cr group, and the 1/creatine versus time slope were found to be significant ( P = 0.027, P = 0.028, P P = 0.044, respectively). The marginal means of PTH, adjusted with the general factorial analysis of variance across the three groups were: ( a ) mild CRF group, BB 5.3 pmol/liter (CI 0 to 13.8), Bb 5.5 pmol/liter (CI 2 to 9), bb 5.4 pmol/liter (CI 0.6 to 10.2); ( b ) moderate CRF group, BB 6.2 pmol/liter (CI 1.5 to 10.9), Bb 7.8 pmol/liter (CI 5.3 to 10.3), bb 7.5 pmol/liter (CI 4.8 to 10.1); ( c ) severe CRF group, BB 9.3 pmol/liter (CI 4.2 to 14.3), Bb 17.1 pmol/liter (CI 13.9 to 20.2), bb 21.9 pmol/liter (CI 18.7 to 25.2). The marginal means of calcitriol adjusted with the general factorial analysis of variance across the three groups were: ( a ) mild CRF group, BB 47 pg/ml (CI 37 to 57), Bb 40.9 pg/ml (CI 37 to 44.8), bb 32.6 pg/ml (CI 26.8 to 38.4); ( b ) moderate CRF group, BB 24.1 pg/ml (CI 18.3 to 29.8), Bb 26.6 pg/ml (CI 23.5 to 29.7), bb 25.3 pg/ml (CI 22 to 28.6); ( c ) severe CRF group, BB 27.4 pg/ml (CI 21.3 to 33.5), Bb 19.4 pg/ml (CI 15.5 to 23.2), bb 20.4 pg/ml (CI 16.1 to 24.7). Conclusion The progression of hyperparathyroidism is slower in predialysis patients with BB genotypes than in the other genotypes. Also, calcitriol levels are less reduced in the BB genotype, which may act to lessen the severity of secondary hyperparathyroidism.
Databáze: OpenAIRE
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