ABSTRACT
The aim of the present work was to study serum calcium, parathyroid hormone [PTH] and Calcidiol [25- hydroxyl vitamin D] in children with the first attack of nephrotic syndrome [NS]. The study was conducted on ten patients with minimal change NS [MCNS] [group I] and ten patients with non-MCNS [group II]. They were I1 males and 9 females, their age ranged from 2 to 11 years. Minimal change NS was diagnosed according to the criteria of the International Study of Kidney Diseases in Children [ISKDC]. Ten healthy children of matching age and sex served as a control group. Patients who received medications known to affect calcium and vitamin D metabolism were excluded. All patients had adequate sun exposure and normal diet except for salt restriction. All patients were studied during the active stage of their initial attack. They had nephrotic range proteinuria, hypoalbuminemia, hypercholesterolemia, normal renal function and were not bed ridden. Total serum calcium [Ca], ionized Ca, phosphorus, alkaline phosphatase [ALP], PTH and Calcidiol were measured in cases and controls. The investigations were repeated in-group I after remission. Urinary Ca and phosphorus output were measured in nephrotic children. None of the patients had tetany or other hypocalcemia manifestations. Mean values of total serum Ca and 25[OH] D were significantly lower in both nephrotic groups compared to the control group [P0.000]. The mean values of serum ionized Ca, phosphorus, ALP, PTH, urea and creatinine did not show any statistically significant difference between the studied groups. Total serum Ca after remission was not significantly different from the control group. Serum ionized Ca, phosphorus, and ALP did not show any statistically significant difference between the active stage, remission or control group. PTH was significantly higher during active stage than in remission [P0.004]. The mean value of 25[OH] D increased offer remission [P=0.001], but its level was still significantly lower than the control group [P0.000]. Hypocalcaemia [> 2 mg/kg/day] was evident in the MCNS group. Urinary phosphorus output was normal in both nephrotic groups
Conclusion: this study showed a subclinical compensatory hyperparathyroidism during protein uric phase of initial attacks of NS evidenced by normal serum ionized calcium, low 25 [OH] D and relative increase of PTH. There was no true hypocalcemia in studied cases; total serum calcium being partly albumin-bound was reduced due to associated hypoalbuminemia. Thus, the routine use of vitamin D and calcium supplementation during the initial attacks of NS are not recommended