INDEXES OF INTACT SERUM PARATHYROID-HORMONE AND RENAL EXCRETION OF CALCIUM, PHOSPHATE, AND MAGNESIUM

Up to data reference ranges were established for fasting renal excretion of calcium, phosphorus, and magnesium on 101 healthy children aged 2-15 years. A normal range for intact parathyroid hormone was also measured. The indices of calcium and magnesium excretion showed no correlation with age or sex so that a common range for all children could be established. The 97th centile values for urinary calcium:creatinine and magnesium:creatinine ratios were 0.69 mmol:mmol and 1.05 mmol:mmol respectively. The calculated tubular maximum for phosphate/litre of glomerular filtrate (TmPO4/GFR) showed no correlation with age with a geometric mean value of 1.67 mmol/l. The normal range for intact serum parathyroid hormone for the age group was 11-35 ng/l, which is lower than the adult normal range using the same assay. There was an inverse correlation between TmPO4/GFR and intact parathyroid hormone in this group of normal children.