Jones, James D.

Abstract This study was designed to test the hypothesis that, in a patient with decreased renal function and an increased plasma creatinine concentration, a significant quantity of creatinine is excreted into the gut, as is true of urea and uric acid, and is metabolized by gut flora. [Methyl-14C] creatinine was given intravenously to five patients and [methyl-14C] creatinine or [carbonyl-14C] creatinine was given orally to five patients. Extracts of excreta, plasma, and urine were subjected to ion-exchange chromatography, with monitoring for 14C and for ninhydrin-positive material. Respiratory gases, collected in acid and base, were assayed for radioactivity. Blood specimens were obtained at intervals to furnish data on decay of labeled creatinine in the body pool. The data show that there is a true creatinine deficit (15.9 to 65.7% of the creatinine formed is metabolized or excreted via extrarenal routes) in patients with decreased renal function. In these patients, creatinine is metabolized to CO2 and methylamine, presumably by the microflora of the gut. A significant portion of the carbonyllabeled creatinine appeared in plasma in an unidentified compound.

Abstract A semiautomatic procedure for the direct estimation of both serum calcium and magnesium is described. The indicator used, Eriochrome blue SE (EBSE), has the advantage of stability and freedom from interference by naturally occurring substances. The procedure requires 3-5 min. per sample and is very reproducible. The values obtained agree with those obtained by back-titration of excess chelator and are consistently 0.3 mg./100 ml. less than those obtained by a standard oxalate precipitation method.

Abstract "Creatininase" activity was induced in the colon flora of rats by feeding creatinine. Sarcosine and methylamine were tentatively identified as the major products of the enzymic action. A third (unidentified) compound was observed. These compounds and methylguanidine were labeled in the urine of rats given 14CH3-creatinine orally. The results suggest that creatinine should not be considered biologically inert in animals, especially in those with decreased renal function.

Abstract Blood specimens from normal individuals and patients (with and without blood dyscrasias) were sent through a 1,423-m pneumatic-tube system that included two monitoring devices, three switches, and 67 bends (62 with a 152-cm radius and 5 with a 76-cm radius), and then returned to the central laboratory. Each specimen was thus subjected to twice the trauma it usually would receive during transit. After transit, these specimens and duplicates kept in the laboratory were analyzed in the same manner for serum or plasma Na, K, Cl, CO2, Ca, Pi, LDH, urea, uric acid, glucose, creatinine, total protein, fibrinogen, hemoglobin, and bilirubin. Filling the tubes completely with blood and using a foam-rubber-Iined vinyl insert to hold the specimen tubes in the carrier decreased the differences attributable to transportation. Allowing the blood to clot before transport did not alter the results. Increases attributable to transport occurred only in hemoglobin, LDH, and K. Values were altered considerably less when the transported aliquot made only one leg of the trip via pneumatic tube. The alterations observed for the remaining analyses were within laboratory error. The pH of whole blood and the mean for PCO2 were not significantly altered, while the mean value for PO2, was increased 1.7 (0.5 to 4.5) mm Hg on transport.