Vitamin D metabolite requirements in dialysed children receiving recombinant human growth hormone.

BACKGROUND

The aim of the study was to assess the requirement of active vitamin D in dialysed children during treatment with recombinant human growth hormone (rhGH).

METHODS

Twenty-six children (aged 5-15 years) were treated with rhGH for 6 months. The serum concentration of parathyroid hormone (PTH), alkaline phosphatase (AP), and calcium and phosphorus were measured in two groups of patients studied in the years 1994-1995 (group I) and 1995-1998 (group II) respectively. Group I received a constant dose of alfacalcidol that was sufficient to keep PTH below 200 pg/ml before rhGH treatment began. The serum PTH level was checked every 3 months. Alfacalcidol was administered to group II according to serum PTH levels checked on a monthly basis.

RESULTS

In group I the PTH level increased after 3 and 6 months of rhGH treatment from mean level 73+/-60; 155+/-156 and 344+/-249 pg/ml respectively; P<0.05. AP activity increased after 6 months of treatment from 206+/-99 to 325+/-124 U/l respectively; P<0.01. The calcium level decreased from baseline after 3 months of treatment from 2.36+/-0.21 to 2.17+/-0.12 mmol/l respectively; P<0.05. In group II AP activity increased after 3 and 6 months of treatment from 272+/-169 to 332+/-192 and 404. 9+/-219.8 U/l respectively; P<0.01. The mean level of phosphorus decreased after 6 months from 2.15+/-0.28 to 1.70+/-0.39 mmol/l respectively; P<0.01. In group II the mean dose of alfacalcidol increased by 60.9%.

CONCLUSIONS

In children with end-stage renal failure, higher doses of vitamin D are needed during rhGH treatment. During rhGH treatment, frequent control of serum PTH level is necessary.