American Journal of Clinical Nutrition, Vol 27, 230-233, Copyright © 1974 by The American Society for Clinical Nutrition, Inc.

Nitrogen-15 studies of erythropoiesis during recovery from marasmus

¹ From the Nutrition Research Laboratory, School of Medicine, American University of Beirut, Beirut, Lebanon

The investigators fed ¹⁵N glycine to three marasmic and two control children with the purpose of comparing the rate of synthesis of hemoglobin and the life span of the erythrocyte in normal and recovering marasmic children. Blood and 3-day samples of stool and urine were collected at intervals throughout a period of 150 days. Protoporphyrin was prepared from erythrocytes and coproporphyrin and stercobilin were separated from urine and stool. The ¹⁵N concentration in the various fractions was determined by mass spectrometry. More ¹⁵N glycine was incorporated into heme in marasmus, indicating a faster rate than normal of erythrocyte formation during the early period of repletion. After reaching a peak concentration in the heme at approximately day 20, the concentration of ¹⁵N in marasmus falls steadily for nearly 60 days, without the parallel high excretion of labeled porphyrins which would occur if this was due to red cell destruction. The fall in concentration can therefore be explained only by expansion of the red cell number with unlabeled erythrocytes. Maximum labeled porphyrin excretion occurred between days 100 and 120 in both groups of subjects, suggesting that red-cell life span is within the normal range during recovery from marasmus.