METABOLISM 



Assessment of Nutritional Status 



The daily output of riboflavine is an unreliable method of assessing 

 riboflavine deficiency/* since it only reflects the immediate dietary 

 intake, A more satisfactory method of assessing nutritional status is 

 to measure the response to a test dose of pure riboflavine, the method 

 being similar in principle to that used in nutritional surveys relating 

 to aneurine (see page 63). 



V. A. Najjar and L. E. Holt/* for example, employed intravenous 

 injection of i mg, of riboflavine and found that the amount of ribo- 

 flavine excreted in the urine at half -hourly intervals was related to the 

 degree of riboflavine deficiency. M. Swaminathan '^ administered test 

 doses of I to 10 mg. orally to adequately nourished subjects and found 

 that 80 to 85 % was excreted within twenty-four hours, whereas Keys 

 et al.}^ who administered a i-mg. test dose to young men on a diet 

 supplying slightly sub-optimal amounts (0-31 mg. per 1000 cals.) of 

 riboflavine obtained only a 12 % recovery in the urine. Similarly, 

 R. D. Williams et al}^ observed a progressive decrease in the urinary 

 excretion of a 2-mg. test dose administered to a subject maintained 

 on a diet providing 0-35 mg. of riboflavine per 1000 cals. 



Axelrod et al.}'^ however, claimed that even the test dose method 

 was unsatisfactory for assessing nutritional status. They gave doses 

 of 200 and 400 /xg. of pure riboflavine per kg. of bodyweight to several 

 subjects, and failed to find any correlation between the percentage of 

 the test dose retained and the amount excreted in the urine. 



The volume of work carried out on the assessment of riboflavine 

 deficiency by measuring the urinary excretion with or without ad- 

 ministration of a test dose is considerably less than that undertaken 

 in the case of aneurine (see page 63) or of nicotinic acid (see page 252), 

 and it is therefore impossible to reach any definite conclusion about 

 the merits of the saturation test. 



In spite of this, however, many attempts have been made to lay 

 down criteria for diagnosing riboflavine deficiency. According to 

 Feder et al.}^ an excretion of less than 0-3 /xg. of riboflavine per ml. 

 of urine is indicative of riboflavine deficiency, whilst the concentration 

 of riboflavine in a sample of fasting- morning urine was claimed to be 

 as valuable as a saturation test for estimating the degree of riboflavine 

 deficiency. Oldham et al}^ aL^o reported a close relationship between 

 the excretion rate and the response to a test dose, and suggested that 

 the elimination of i /xg. of riboflavine per hour by a fasting subject or 

 the elimination of 20 % of a test dose within four hours of its adminis- 

 tration was indicative of an adequate level of nutrition. 



Hagedorn et al.'^^ reported that an adult male, receiving 0-5 mg. 

 of riboflavine daily for five years, showed no signs of ribofl vine 



179 



