ZINC CHANGES IN BLOOD AND URINE DURING CYCLIC PARENTERAL-NUTRITION - RELATIONSHIPS WITH AMINO-ACID-METABOLISM

Serum Zn, ultrafiltrable Zn and amino acids in serum and urine samples of twenty-seven patients receiving cyclic (12 h/24 h) parenteral nutr ition were measured. These samples were collected in patients after a 12 h period of parenteral nutrition, and in the evening after 12 h wit hout parenteral nutrition. The same determinations were performed in t en control subjects who followed the same sampling scheme. Total serum ultrafiltrable Zn showed no significant variations in the patients du ring parenteral nutrition, and was not significantly different in the two groups although the proportion of the Zn present in the ultrafiltr able fraction was elevated. Serum cystine levels were significantly hi gher (P = 0.05) in the patients than the control subjects, and cystine excretion was also higher in patients (P < 0.05) and increased after parenteral nutrition (56.0 (SE 6.5) v. 147.1 (SE 20.6) mu mol/12 h; P < 0.001). Histidine levels did not vary significantly in serum after p arenteral nutrition and were not different in the patients in comparis on with the control subjects. Histidine excretion was not different in the two groups but increased significantly during parenteral nutritio n (P < 0.05). Serum albumin was significantly depressed in the patient s compared with the control subjects (45.3 (SE 1.5) v. 33.9 (SE 1.5) g /l; P < 0.001). These results suggest that cystine infusion and excret ion relate to the changes occurring in serum Zn and in urinary Zn excr etion.