Does the vitamin D receptor genotype predict bone mineral loss in haemodialysed patients?
BACKGROUND
It has been suggested that the vitamin D receptor (VDR) gene BsmI-polymorphism is a genetic determinant of bone metabolism.


METHODS
To test this hypothesis, the relationship between VDR genotypes, bone mineral density (baseline and after 18 months) and parameters of calcium metabolism and bone turnover were investigated prospectively in 88 haemodialysed patients not receiving active vitamin D metabolites.


METHODS
Whole body, lumbar spine and femoral neck bone mineral density (BMD) were assessed by dual energy X-ray absorptiometry (DEXA). In addition calcium, phosphorus, 25(OH)D3, 1,25(OH)2D3, osteocalcin serum concentrations, alkaline phosphatase activity and intact 1,84 PTH levels were measured.


RESULTS
VDR genotype BB, Bb and bb were found in 27, 49 and 24% of patients. Initial BMD (g/cm2) of whole body, lumbar spine and femoral neck did not differ between genotypes (whole body: BB 1.055 +/- 0.120, Bb 1.082 +/- 0.102, bb 1.128 +/- 0.120; lumbar spine: BB 1.075 +/- 0.199, Bb 1.079 +/- 0.185, bb 1.099 +/- 0.170; femoral neck: BB 0.808 +/- 0.160, Bb 0.862 +/- 0.127, bb 0.842 +/- 0.125; mean +/- SD), but the decrease of whole body and femoral neck BMD during 18 months was significantly (P < 0.02) different between the genotype groups (whole body: BB -0.048 +/- 0.028, Bb -0.031 +/- 0.029, bb -0.024 +/- 0.023; femoral neck BB -0.044 +/- 0.069, Bb -0.032 +/- 0.081, bb -0.012 +/- 0.029 g/cm2).


CONCLUSIONS
This preliminary study suggests faster mineral loss in BB genotype of VDR in haemodialysed patients.
Karkoszka
H
H
Department of Nephrology, Endocrinology and Metabolic Diseases Silesian University School of Medicine, Katowice, Poland.
Chudek
J
J
Strzelczyk
P
P
Wiecek
A
A
Schmidt-Gayk
H
H
Ritz
E
E
Kokot
F
F
D000293:Adolescent; D000328:Adult; D000368:Aged; D015519:Bone Density / Q000502:physiology; D005260:Female; D005272:Femur Neck / Q000378:metabolism; D005544:Forecasting; D005838:Genotype; D006801:Humans; D008161:Lumbosacral Region; D008297:Male; D008875:Middle Aged; D018167:Receptors, Calcitriol / Q000235:genetics*; D006435:Renal Dialysis; D012727:Sex Characteristics; D013131:Spine / Q000378:metabolism
D018167:Receptors, Calcitriol