The aim was to estimate Vitamin D3 (25OHD) level and its relation to secondary hyperparathyroidism (SHPT) development in patients with different stages of chronic kidney disease (CKD).
We examined 114 patients, 71 f, 43 m; age 44.6±14.3 years. CKD stage was defined by estimated glomerular filtration rate (eGFR) calculated by MDRD formula. 48 patients have CKD stage 12, 26 pts CKD3, 27 pts CKD4, 13 pts CKD5 (not on dialysis). Serum PTH, 25OHD, calcium (Ca) and phosphorus (P) were measured. All patients did not receive vitamin D and/or calcium supplements.
Mean PTH level was 120.7±113.4 pg/ml (95%CI 96.0145.5). Frequency of SHPT was 44.7% in whole group, 12.5% in patients with CKD 12 stages, 23.1% - in CKD3, 96.3% - in CKD4, 100% - in CKD5. In patients with eGFR <45 ml/min elevated PTH level was in 95.6% of cases vs 11.6% of those with eGFR ≥45 ml/min (P<0.00001).
Mean 25OHD level was 18.6±8.4 pg/ml (95%CI 17.020.1). Only in 7.9% of whole group 25OHD was 30 ng/ml and above (recommended level), in 55.3% - <20 ng/ml (vitamin D deficiency). 25OHD level significantly correlated with eGFR (r=0.47), PTH (r=−0.39), age (r=−0.23), Ca (r=0.27) and P (−0.20) levels. Frequency of 25OHD deficiency in patients with eGFR≥45 ml/min was 40.6, and 77.8% in those with eGFR<45 ml/min (P=0.0002). In subgroup of patients with decreased 25OHD level PTH and P were significantly higher (156.9±147.7 vs 75.8±77.2 pg/ml; 1.33±0.38 vs 1.17±0.22 mmol/l, P<0.001), Ca was lower (2.31±0.30 vs 2.43±0.18 mmol/l, P=0.0002).
We can assume that vitamin D3 deficiency is very common in patients with advanced CKD stages and associated with higher PTH level and more profound mineral disturbances. Screening of both PTH and 25OHD3 levels in patients with eGFR <45 ml/min seems to be reasonable for choosing of best strategy of medical care.