Reproducibility of the hepatic uptake test of vitamin B12 absorption.

The absorption of vitamin B12 can be determined by several methods based on the measurement of the radioisotope-labelled vitamin in serum, faeces, and urine, and by external counting over the liver. In general these test procedures distinguish clearly between normal values and those obtained in individuals with pernicious anaemia, but it has been claimed that serial tests by the Schilling urinary excretion method failed to give results which were consistently normal or abnormal in patients with primary malabsorption syndromes or who had had a partial gastrectomy (Adams and Cartwright, 1963). These discrepancies could be due in part to difficulty in ensuring complete urinary collections in those with diarrhoea, and perhaps to variation in flushing of the dose absorbed. Another, more direct technique might therefore, prove more satisfactory. Results obtained with the hepatic uptake test have been shown to agree well with those given by the faecal excretion method when both were performed simultaneously (Fone, Cooke, Meynell, and Harris, 1961) and the hepatic uptake test has the advantage that it avoids the problems of complete urinary or faecal collection, which can be considerable in patients with malabsorption syndromes. We have therefore studied the repro-ducibility of the hepatic uptake test 1957) by performing the examination on two occasions in individuals with malabsorption syndromes and in those who had had a partial gastrectomy. The results have been compared with those obtained in patients with pernicious anaemia and in individuals without evidence of gastrointestinal disease. The hepatic uptake of radioactively labelled cyano-cobalamin was determined on two occasions one week to one month apart in patients with pernicious anaemia ' or malabsorption syndromes, after partial gastrectomy, and in a group without gastrointestinal disease. 58Co labelled cyanocobalamin of specific activity 1 1uCi per microgram was used in these investigations. At each testO-5 ,ug of the labelled vitamin was given in the morning by mouth in 100 to 200 ml of water. Each patient ate a normal breakfast beforehand, for there is evidence that, at least after partial gastrectomy, vitamin B1, absorption is reduced by fasting (Deller, Germar, and Witts, 1961). After one week hepatic radioactivity was determined using a scintillation counter having a 14 in. diameter x 1 in. diameter sodium iodide crystal and fitted with a wide angle collimator. Counts were made for five minutes each at the centre of liver dullness in the midclavicular and midaxillary lines, over the anterior or posterior aspect of …