The validity of skeletal muscle function as a functional measure of nutritional state was determined by stimulating the ulnar nerve at the wrist and measuring the force of isometric contractions of the adductor pollicis muscle. Nutritional state was evaluated by measuring body composition, by multiple-isotope dilution, in 21 malnourished and 44 normally nourished patients. No significant correlation between body composition and muscle function was found. In eight normally nourished volunteers, muscle function was determined before, after 24 and 48 h of complete starvation, and 6, 24, and 48 h following resumption of normal diet. Muscle function became abnormal after 24 h of starvation and deteriorated further after 48 h. Six hours following a single normal meal, muscle function returned to normal. Experimental data indicate that the response of the adductor pollicis muscle to ulnar nerve stimulation is not an accurate measure of nutritional state.

The present study evaluated the sensitivity and specificity of the serum transferrin concentration as a measure of the nutritional state. Serum transferrin was derived from total iron-binding capacity measurements in 74 patients on 114 occasions and correlated with body composition as measured by multiple isotope dilution. Highly significant correlations (p less than 0.001) existed between serum transferrin and both the body cell mass and the nutritional state as measured by the Nae/Ke ratio. However, the 95% confidence limits about both regressions were wide. The false-positive rate was 60% while the false-negative rate was 31%. Body composition and transferrin were measured before and after 2 wk of total parenteral nutrition in 34 malnourished patients. Eighteen patients restored body cell mass toward normal after 2 wk of total parenteral nutrition while in 16 patients the body cell mass continued to decrease in size, despite 2 wk of total parenteral nutrition. The changes in serum transferrin were not significant over this period of time in either group, despite significant changes in the nutritional state in both groups. The presence of a statistically significant relationship between the serum transferrin concentration and the nutritional state indicates that the serum transferrin concentration accurately reflects a population's nutritional status, and is therefore useful in epidemiologic surveys. However, because of the large variance of the data, as demonstrated by the wide 95% confidence limits, and because of the poor sensitivity and specificity, in an individual patient it is of little value as a measure of the nutritional status.