The tubular maximum for calcium reabsorption: a normal range in children.

OBJECTIVE

We aimed to establish a normal range for the tubular maximum rate of reabsorption of calcium corrected for glomerular filtration rate.

DESIGN

A prospective survey was used.

PATIENTS

One hundred and ten normal children aged 2-14 years were studied.

MEASUREMENTS

Total plasma calcium, ultrafiltrable calcium and parathyroid hormone. Urinary calcium, sodium and creatinine excretion.

RESULTS

The normal range was found to be 1.87-3.39 mmol/l of glomerular filtrate with a geometric mean value of 2.40 mmol/l. There was a significant inverse relationship between the tubular maximum for calcium and the urinary sodium excretion. No significant relationship was found between the tubular maximum for calcium and the level of parathyroid hormone in this group of normal children.

CONCLUSIONS

The normal range seen in children is higher than that seen in adults with a higher mean value. This normal range should be useful in the assessment of renal calcium handling in children with disorders of calcium homeostasis.