F(1) and F(2) of Najjar and Holt in the Urine of Normal Young Men.

Najjar and Holt (1, 2) have demonstrated that their fluorescent urinary pigments, F1 and F2, are related to nicotinic acid metabolism in such a way that their estimation in urine is of diagnostic use in human pellagra (1) and in canine black tongue (1, 2). As nicotinic acid deficiency progresses, the daily excretion of F1, starting from a low level, slowly rises and then falls again; and the daily excretion of F2, starting from a normal level, falls progressively to zero. Vigorous treatment of pellagrins with nicotinamide causes, within 3 days, a large increase in F2 and a decrease in F1. Extending this work, Holt and Najjar (3, 4, 5) proposed the routine measurement of urinary F2 in nutritional surveys as an indication of the nicotinic acid content of the body. They state that when F2 is absent in urine collected in the post-absorptive state,3 the patient's stores of nicotinic acid are low. Oral administration of nicotinamide to normal subjects in a good nutritional state leads to a prompt increase in F2, maximal in 2 to 4 hours and subsiding to normal within 6 hours. Coulson and his coworkers (6) have also made a detailed study of the effects of various nicotinic acid derivatives on urinary F2 estimations. Their results are much the same as those of Najjar and Holt. In developing suitable rapid field methods for