Total body nitrogen in children with chronic renal failure and short stature.

OBJECTIVE

To directly assess the body protein content of children with chronic renal failure (CRF) and short stature.

SETTING

A tertiary referral paediatric hospital.

SUBJECTS: There were: (i) 17 patients (10 male, nine pre-pubertal; mean age 12.90 +/- 3.20 years) with CRF and height standard deviation (SD) score < -2.00, and (ii) 43 normal children (18 male, 27 pre-pubertal; mean age 10.34 +/- 3.34 years).

INTERVENTIONS: CRF patients had the following measurements: anthropometry, total body nitrogen (TBN) by neutron capture analysis, 4 day weighed food record and serum albumin levels. Control subjects had TBN and anthropometric measurements only.

RESULTS

Although older than the controls, the CRF patients had significantly lower TBN values (645 +/- 265 vs 930 +/- 365 g, P < 0.01). Mean values for TBN and TBN/height (percentages of expected) in the CRF patients were significantly reduced to 54% and 63% respectively, when predicted from age. However, their TBN predicted from height was 100% of expected. %TBN (predicted from age) correlated significantly with height SD score (r = 0.79), weight SD score (r = 0.87), upper arm muscle area percentile (r = 0.62) and serum albumin (r = 0.62). Mean oral energy and protein intakes were 65% and 172% of recommended dietary intake respectively.

CONCLUSIONS

Children with CRF and short stature are significantly protein-depleted for age although not for height. Chronic energy deficiency may contribute to impaired protein deposition which, in turn, may be important in the pathogenesis of growth failure in CRF.