BONE ALKALINE-PHOSPHATASE IN CHILDREN WITH CHRONIC-RENAL-FAILURE

Background. With the introduction of a new immunoradiometric assay bas ed on two monoclonal antibodies (Tandem(R)-Ostase, Hybritech) the dete rmination of bone alkaline phosphatase (BAP) to evaluate bone metaboli sm in chronic renal failure has become easier and more valid. Subjects and methods. Using this test we investigated BAP in a total of 90 pae diatric patients, 42 (9.2 +/- 5.5 years) with chronic renal failure on conservative treatment, 22 (9.5 +/- 5.4 years) under chronic dialysis , and 26 (16.2 +/- 5.9 years) after renal transplantation, compared to 203 controls (10.1 +/- 5.7 years). Results. The physiological age dep endency found in controls including two peaks during infancy and puber ty was distinctly disturbed in chronic renal failure. However, in pati ents BAP significantly correlated with height velocity rather reflecti ng the last 6 (r = 0.56 P < 0.001) than the last 12 months. Although B AP correlated well with total alkaline phosphatase (TAP; r = 0.95 P < 0.001), a significant correlation with the serum level of the intact p arathyroid hormone could only be detected for BAP (r = 0.45 P < 0.001) but not for TAP (r = 0.19 n.s.). Furthermore, BAP positively correlat ed with trabecular (n = 40; r = 0.40 P < 0.05) and inversely with cort ical bone density (n = 19; r = -0.58 P < 0.01) but no relationship was found with conventional X-ray. Conclusion. BAP determined by the new radioimmunoassay seems to represent an additional diagnostic tool to a ssess growth and bone turnover in paediatric patients with chronic ren al failure that is complementary to the information provided by X-ray and total alkaline phosphatase.