Serum transthyretin levels and protein intake as predictors of weight gain velocity in premature infants

Nutritional intakes, transthyretin (preal, bumin) levels, and anthropometric measurements were measured weekly in 26 preterm infants from week 2 of life throughout hospitalization. A sustained significant increase in protein intake occurred in 14 infants over a 2, week period. When mean protein intake increased, mean transthyretin levels increased during the same week (p < 0.001), followed 1 week later by significant increases in mean weight, occipitofrontal head circumference (OFC), and mid, arm circumference (MAC). In the other 12 infants, a sustained significant decrease in protein intake occurred over 2 weeks. When mean protein intake decreased (p < 0.01), transthyretin levels decreased during the same week (p < 0.05), followed I week later by signif, icant decreases in mean weight and MAC growth. Over all hospitalization weeks (n = 95), rates of weight gain were more significantly associated with previous trends in transthyretin levels (p = 0.007) than with protein intake alone (p = 0.08). In particular, declines in rates of weight gain were predicted significantly more frequently by the prior week’s transthyretin trend (70%) than by the trend in protein intake (47%). In growing premature infants, changes in transthyretin levels occur 1 week before changes in anthropometric measurements. Changes in transthyretin levels are more predictive than changes in protein intake alone for monitoring growth velocity in preterm infants.