Taurine concentrations were measured in plasma and blood cells of 40 adults undergoing long-term parenteral nutrition, without intravenous taurine, for 43.8 +/- 35.1 (SD) mo. Patients were classified into Group 1 (21 patients) or Group 2 (19 patients) according to whether their estimated enteral absorption of calories was less or greater than 25% of their daily requirement, respectively. In Group 1, taurine concentrations were reduced to 35-49% of normal control values in plasma (p less than 0.01), platelets (p less than 0.001), lymphocytes (p less than 0.005), and erythrocytes (p less than 0.001). Granulocyte taurine was not different from normal. A smaller decrease in taurine concentration was found in Group 2 patients; however, taurine levels were significantly below normal in their plasma and red cells. Thus, many patients undergoing long-term parenteral nutrition with little or no taurine intake are depleted of taurine in plasma and most blood cells. These findings suggest that taurine may be essential for these patients and should be added to solutions used for long-term parenteral nutrition.
ABSTRACT. Taurine concentrations in plasma, platelets, lymphocytes, granulocytes, erythrocytes, and urine were measured in 19 children who were undergoing long-term home parenteral nutrition for 27.4 k 7.1 (SEM) months. The parenteral solutions contained methionine, but not taurine or cysteine. The patients' plasma, platelet, and urine taurine concentrations were significantly reduced to 54, 48, and 16%, respectively, of the values from normal children of similar ages. The most significant reductions in plasma and platelet taurine concentrations were observed in the children who were estimated to absorb less than 5% of their daily calorie needs from the enteral tract. Lymphocyte and erythrocyte taurine levels tended to be lower but were not significantly different from those in normal children. The patients' plasma methionine and cystine levels were not different from normal. There was a direct correlation between plasma and platelet taurine concentrations and between plasma and urine taurine. Both plasma and platelet taurine tended to be directly correlated with age and, after the 1st yr of total parenteral nutrition, with the duration of total parenteral nutrition therapy. The question of whether taurine (2-aminoethanesulfonic acid) may be an indispensable amino acid for humans has been the subject of much research in recent years. Studies in premature and term infants have shown that a low or absent dietary taurine intake (either from formula feedings or parenteral nutrition solutions) is associated with low plasma and urine taurine levels (1-5). We have previously reported that children undergoing long-term TPN at home with solutions that do not contain taurine have low plasma taurine levels and abnormal ERG (6). These studies suggest that taurine is an indispensable amino acid.However, taurine, which is one of the most abundant free amino acids (i.e. not bound in peptides or protein) in the human body, resides almost entirely within the cell. Intracellular taurine
To evaluate the effects of long-term total parenteral nutrition (TPN) on eye function, 27 adults and 12 children in the UCLA Home TPN Clinic underwent ophthalmoscopic examination and visual-function testing. Direct inspection of the fundus showed a marked granularity of the retinal pigmented epithelium in some patients. About one-half of the children and one-third of the adults tested had at least one and usually two abnormalities in their electroretinogram. Determination of blood nutrients thought to affect vision revealed that zinc and vitamin E were within normal range. Vitamin A concentrations were above normal in 10 of 19 adults and selenium concentrations were below normal in 10 of 10 children and 17 of 21 adults tested. Linoleic and linolenic acid concentrations were low; plasma, platelet, and urine taurine concentrations were significantly lower than normal. Despite these diffuse nutrient abnormalities, only zinc and vitamin E concentrations correlated significantly with any index of visual function.
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