A Study of Urinary Riboflavin Excretion in Man 1

Abstract

The occurrence of riboflavin deficiency in man has been described by several investigators (1 to 5). Since urinary excretion tests have proved to be of considerable value in the diagnosis of thiamin and ascorbic acid deficiencies, the present study was undertaken to determine the value of such tests in the diagnosis of riboflavin deficiency.A pronounced decrease in the urinary riboflavin excretion has been observed in rats and dogs maintained on riboflavin-low diets (6,7,8). Spies, Bean and Ashe (9) have reported a decrease in the amount of riboflavin present in the urine of pellagrins with riboflavin deficiency, and Emmerie (10) has observed that urinary riboflavin excretion of a subject on a diet restricted in riboflavin was 43 to 60 per cent of that observed when the subject was on a normal diet. Both groups of investigators (9, 10) noted that the administration of riboflavin was followed by a rapid excretion of the vitamin in the urine. Neuweiler (11) reported a case of ariboflavinosis in an infant who completely retained large doses of riboflavin. MATERIAL AND METHODSFive patients in the Nutrition Clinic of the Hillman Hospital, Birmingham, Alabama, were chosen for this study. This group (Cases I, II, III, IV and V) consisted of malnourished persons who were suffering from a multiple vitamin deficiency. They were hospitalized throughout the study and were restricted to diets deficient Twenty-four-hour urine specimens were collected from each patient in dark bottles containing 1 cc. of glacial acetic acid and a small amount of toluene. The volume was measured and aliquots were brought to pH 6.6 and stored in the refrigerator under toluene. Samples were collected over a period of two to four weeks.The riboflavin content of the urine was determined by the microbiological method of Snell and Strong (12). The reliability of this method for the determination of both the free and combined forms of riboflavin in a number of biological fluids has been adequately established (12, 13). When necessary, the urine was diluted with distilled water in order to adjust the riboflavin content to the correct assay range (approximately 0.1 microgram of riboflavin per ml.). All assays were made at three different levels, each level being run in duplicate. It was found that the sample of urine could be stored in the refrigerator for a period of two weeks with no loss in the riboflavin content.The "saturation" tests were performed by administering riboflavin through intravenous injection and determining the riboflavin content of the following twenty-

Absorption and Excretion of Riboflavin in the Rat: An Unusual Example of Nonlinear Pharmacokinetics

“…Further inspec- Mean f S D of the mean, urine collected over a 72-hr. These findings are analogous to the results in human subjects reported by Najjar and Holt (9) and Axelrod et al (10). The urinary recovery of riboflavin expressed as a percent of dose in bile duct-ligated animals increases substantially when the dose is increased fivefold.…”

Enzyme inhibition by allicin, the active principle of garlic

“…(b) From liver. This was prepared from rat liver either as described by Axelrod & Elvehjem (1941), or by I. Lewin (private communication). The enzyme activity was estimated manometrically with hypoxanthine as substrate, as previously described (Wills & Wormall, 1950).…”

Enzymatic Reactions Involving Nicotinamide and Its Related Compounds

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