Renal hypophosphatemic rickets. Growth and mineral metabolism after treatment with calcitriol (1,25-dihydroxyvitamin D3) and phosphate supplementation
N. Tsuru, J. C. Chan and V. M. Chinchilli
To delineate the mineral metabolism of renal hypophosphatemic rickets and
to update progress in linear growth after calcitriol (1,25-dihydroxyvitamin
D3) therapy, the medical records of 19 patients were examined
retrospectively from January 1978 through December 1985. With a mean (+/-
SD) follow-up period of 42.0 +/- 5.4 months after calcitriol had been
administered for at least 12 months, the growth measurements were as
follows: the percentile weight (mean +/- SD) remained unchanged, with the
initial being 12.3% +/- 17.3% and the final being 15.3% +/- 18.6%, and the
length/height percentiles were -2.7% +/- 5.9% and -2.4% +/- 4.4%. The
growth velocity index showed a significant improvement from mean values of
61.7% (at age 2 years) to mean values of 101.2% (at age 11.2 years). Serum
phosphate concentrations rose from the initial value of 2.9 +/- 0.6 to 3.5
+/- 0.8 mg/dL (0.9 +/- 0.2 to 1.1 +/- 0.3 mmol/L). The effects of
calcitriol on renal function were tested by creatinine clearance values,
which were 127 +/- 22 mL/min/1.73 m2 (2.12 +/- 0.37 mL/s/1.73 m2) at the
conclusion of the study, compared with 128 +/- 25 mL/min/1.73 m2 (2.13 +/-
0.41 mL/s/1.73 m2) obtained at the initiation of calcitriol therapy. We
conclude that calcitriol treatment of renal hypophosphatemic rickets in
children results in improvement of growth velocity and serum phosphate
concentration without deterioration of renal function.
