[Parameters of bone metabolism in patients with various degrees of kidney function damage]

Patients with renal failure frequently have their calcium and phosphate metabolism seriously disrupted. It may result in a skeletal malady--the renal osteopathy. Late forms of this syndrome are difficult to cure. The aim of this comparative study is to follow the relation between parameters of the bone metabolism (calcitriol, calcidiol, parathormone, calcitonin, osteocalcin, Pi, Ca--total or ionised, and others) and the degree of deterioration of the kidney function.

Three groups of patients were included into the study: A-hemodialyzed patients with chronic renal failure (Ccreat = 0.07 +/- 0.02 ml/s, n = 21, age 71.0 +/- 10.6 years); B--not dialyzed patients with decreased renal function (Ccreat = 0.33 +/- 0.05 ml/s, n = 19, age 65.0 +/- 9.6 years); C--patients with normal renal function (Ccreat = 1.45 +/- 0.12 ml/s, n = 16, age 85.2 +/- 4.7 years). Calcidiol concentration [microgram/l] did not differ in individual groups (A: 11.3 +/- 4.7, B: 10.7 +/- 8.2, C: 11.7 +/- 5.7, reference limits RM: 8.9-46.7). In contrast, calcitriol concentration [ng/l] was statistically different in all studied groups (A: 1.7 +/- 2.8, B: 17.6 +/- 12.4, C: 30.6 +/- 9.1, p < 0.001, RM: 19.9-67.0) and it correlated with the degree of renal function deterioration (calcitriol vs. creatinine, r = -0.76, p < 0.001). In PTH levels (pmol/l) the group C differed significantly from groups A and B (A: 27.4 +/- 32.0, B: 23.7 +/- 16.5, C: 6.2 +/- 2.4, C vs. A, p < 0.01, C vs. B, p < 0.001, RM: 1.0-6.8). PTH concentrations correlated with osteocalcine and HCO3 (r = 0.74, r = -0.56, p < 0.001).

Results of the tested parameters have shown that abnormalities in the bone metabolism significantly correlate with the degree of renal deterioration. It demonstrates the requirements for vitamin D metabolites supplementation for patients is needed already in the pre-dialysis stage.