[Dynamics of bone biochemical markers in nephrotic children treated with prednisone and metabolites of vitamin D].
Children with idiopathic nephrotic syndrome (NS) are at risk for a disorder of bone metabolism. The role of metabolites of vitamin D supplements in prevention of this disorder has not been yet clarified. The aim of the study was to evaluate changes in selected bone biochemical markers in children with NS treated with different doses of prednisone and metabolites of vitamin D.


METHODS
40 patients with NS (mean age 9.2 +/- 3.6 years) treated with prednisone were evaluated in three groups depending on supplementation with metabolites of vitamin D: I--18 patients with alphacalcidol (0.05 mg/kg/week); II--10 patients with vitamin D (800 IU/day); III--12 patients without metabolites of vitamin D. In all patients, calciuria (Cau), phosphaturia (Pu), serum calcium (Cas), phosphate (Ps), parathyroid hormone (PTH), alkaline phosphatase (AP), carboxyterminal propeptide of type I procollagen (PICP), carboxyteminal pyridinoline cross-linked telopeptide of type I collagen (ICTP) and PICP/ICTP ratio were checked three times: T0--before prednisone treatment; T1--after 2 weeks of therapy with prednisone 2 mg/kg/24h; T2--after 2 weeks of treatment with prednisone 2 mg/kg/48h.


RESULTS
Mean Cau and Pu values found at T1 were significantly higher and mean values of Ps, AP, PICP, ICTP concentration and PICP/ICTP ratio were significantly lower in 3 groups of pts in comparison to TO. A significant increase of Cas concentration was found in group I and control group, but there were no significant differences among values of Cas in 3 groups. In T2 period PICP and PICP/ICTP ratio increased (T2 vs T1) in all groups, however mean values of AP did not change significantly. Moreover, there was an increase of Cas and decrease of PTH in group I. In group I and II, levels of phosphaturia showed a significant difference among 3 studied groups.


CONCLUSIONS
1. The method of corticosteroid administration influences dynamics of selected bone biochemical markers in nephrotic children: short-term treatment with high daily doses is associated with increased calciuria and phosphaturia, decreased activity of alkaline phosphatase and suppression of serum markers of type I collagen's turnover (PICP, ICTP, PICP/ICTP ratio); decrease of corticosteroid dose leads to increase of these markers. 2. Decreased PICP/ICTP ratio during daily corticosteroid treatment may indicate stronger inhibition of bone formation than bone resorption. 3. Dynamic changes in studied bone biochemical markers in nephrotic children treated with prednisone do not depend on supplementation with vitamin D or alphacalcidol.
Katedra i Klinika Pediatrii i Nefrologii Akademii Medycznej w Warszawie. nefrologia@litewska.edu.pl
Julita
J
Wojnar
Maria
M
Roszkowska-Blaim
Małgorzata
M
Pańczyk-Tomaszewska
D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D009404:Nephrotic Syndrome / Q000188:drug therapy*; D011241:Prednisone / Q000494:pharmacology / Q000627:therapeutic use*; D014807:Vitamin D / Q000494:pharmacology / Q000627:therapeutic use*
D015415:Biomarkers; D005938:Glucocorticoids; D014807:Vitamin D; D011241:Prednisone