BIOTIN SUPPLEMENTATION AFFECTS LYMPHOCYTE CARBOXYLASES AND PLASMA BIOTIN IN SEVERE PROTEIN-ENERGY MALNUTRITION

We studied the effect of a supplement of biotin (10 mg/d) or a placebo under double-blind conditions on plasma biotin concentrations and lym phocyte propionyl CoA carboxylase (PCC) and pyruvate carboxylase (PC) in 22 children with severe protein-energy malnutrition (PEM) (5 with k washiorkor, 10 with marasmus, and 7 ''sugar babies''). There were sign ificant differences between the malnourished and control subjects only for PCC, although not among the three PEM types. Six of the patients had both PC and PCC activities below the lowest of the normal control subjects; there was no correlation between biotin concentrations and c arboxylase activities in individual patients. In response to biotin su pplementation, the greatest change in lymphocyte carboxylase activitie s was detected in patients who had abnormally decreased initial carbox ylase activities, but the response was not related to initial plasma b iotin concentration. These results indicate that these enzyme deficien cies are the result of a nutritionally determined biotin deficiency, t hat carboxylases and especially PCC are better indicators of the bioti n status in individual patients than is the plasma biotin concentratio n, and that in some malnourished patients biotin deficiency may be rat e-limiting in their nutritional homeostasis.