The effect of protein or energy restriction on the biodistribution of (NaTcO4)-Tc-99-O-m in Wistar rats

The effect of malnutrition on the biodistribution of radiopharmaceuticals i s not known. We studied the biodistribution of Tc-99(m)-labelled sodium per technetate ((NaTcO4)-Tc-99-O-m) in two rat models of malnutrition. Three gr oups of 2-month-old rats were separated according to their diets: (1) contr ol diet, 23% protein (C); (2) protein-restricted, receiving 8% protein (PR) , both nd libitum and (3) energy-restricted, receiving 60% of control diet (ER). After 21 days of the diet, Tc-99(m) was injected and the animals were killed after 30 min. The organs were isolated, their weight determined and the absolute per cent (%ID) and the per cent per gram injected dose (%ID.g (-1)) calculated. The %ID and %ID.g(-1) had a similar pattern, increasing i n stomach and brain and decreasing in the thyroid, but did not change signi ficantly in kidney, lung liver, bone or testis in PR rats, except in the he art where the increase was only observed in the %ID.g(-1). In the ER group the %ID.g(-1) was decreased in the bone only, and did not change in the oth er organs. It is suggested that when using (NaTcO4)-Tc-99-O-m scintigraphy in malnourished patients, the different patterns of distribution must be ke pt in mind. ((C) 2000 Lippincott Williams & Wilkins).