Muscle mass and composition in malnourished infants and children and changes seen after recovery

Abstract

A method for measuring muscle mass in children with [15N]creatine has been used to study changes in muscle after recovery from protein-energy malnutrition. Creatine pool size, muscle mass, total muscle cell number, muscle cell size, and total body water have been measured in seven malnourished and eight recovered children. After recovery there was a significant reduction in the muscle concentration (micrograms mg 1 wet wt muscle) of creatine (4.21 to 3.12), and a trend towards reduction in noncollagen protein (155 to 136) and DNA (2.13 to 1.34). The fractional turnover rate of creatine did not change but the creatine pool size increased significantly (4.2 to 5.6 g). Average muscle mass almost doubled (1.00 to 1.91 kg) and made up a greater percentage of body weight (16 to 22%). When muscle mass was expressed as a percentage of the expected muscle mass for a normal child of the same height the increase with recovery was from 49% to 92%. Total muscle noncollagen protein (NCP) increased after recovery (153 to 265 g) and accounted for a greater percentage of total body solids (6.6 to 8.5%). The average total muscle DNA was 2.049 g in the malnourished and 2.380 g in the recovered children and the ratio of NCP:DNA increased from 92 to 110 on recovery. Total body water as a percentage of body weight was not significantly different after recovery. Values for muscle mass in recovered children were similar to those reported for normal children of the same weight, height, and age. Speculation: In children who have recovered from malnutrition by reaching their expected weight for height, muscle mass repletion is achieved by a combination of cellular hypertrophy and hyperplasia. © 1978 International Pediatric Research Foundation, Inc.