Linear growth and anthropometric and nutritional measurements in children with mild to moderate renal insufficiency: A report of the growth failure in children with renal diseases study

During the control period of the Growth Failure in Children With Renal Diseases Study, investigators at 23 centers were able to observe and characterize growth and to make anthropometric and nutritional measurements in 82 children with mild to moderate renal insufficiency. As a multicenter, controlled clinical trial designed to study the relative efficacy of 1,25-dihydroxyvitamin D₃ and dihyderotachysterol in the treatment of renal osteodystrophy, no prior vitamin D exposure and a creatinine clearance of 25 to 75 ml/min/1.73 m² were criteria for entrance into the clinical trial. Ages ranged from 18 months to 11 years (mean 5.6±3.1 years), and distribution by age category was as follows: 38%, 1 to 3 years; 28%, 4 to 6 years; and 34%, 7 to 10 years. There was a 3:1 male/female ratio; 72% of the patients had congenital disease by the international Classification of Diseases (ninth revision). Mean creatinine clearance was 49.5±20 ml/min/1.73 m². The C-terminal parathyroid hormone values (1121±1562 pg/ml) were well above 2 SD of the mean of a normal growing population of similar age. Parathyroid hormone values correlated with degree of renal insufficiency (r=-0.57) and with height by bone age but not with chronologic height or growth velocity. The bone age/height age ratio, a predictor of growth potential in normal children, was low for the entire series of patients (0.88±0.35) but failed to correlate with growth velocity and was negatively correlated with rising parathyroid hormone levels. Average values for height, weight, triceps skin fold, mid-arm muscle circumference, and body mass index were within 2 SD of the mean of the normal population, although measurements for the 1- to 3-year age group were significantly less than those of the older patients. Total energy intake averaged less than 86% of the recommended dietary allowances; total protein intake was more than 161% of the allowance. Nitrogen balance in 23 patients was positive and correlated most significantly with increasing energy intake (r=0.6). Growth velocity, calculated from the interval gain during the 6-month control period, averaged +0.3 SD, with the highest growth velocity z scores recorded for those with acquired disease. A growth velocity index, expressed as the slope of the regression between change in height SD and growth velocity z score, was used to describe the growth accomplished in the control period by age category. Each of these regressions was significant (r>0.5; p <0.01). Any change in the growth velocity index will serve as a measure of growth response to treatment. These data provide previously unavailable controlled observations of growth and nutrient intake in a substantial number of children with renal insufficiency who have not yet received treatment with vitamin D analogs.