RESUMEN
A case is reported of a patient with idiopathic hypercalcuria who was referred for investigation of renal calculi. Studies of urinary amino acid excretion in the patient and all living members of his family, as well as studies of endogenous renal clearances of dibasic amino acids and cystine in the patient and his daughter, indicated that the patient had genotype +/11 heterozygous cystinuria. Intestinal perfusion studies showed however that the patient was able to absorb L-lysine, L-arginine normally from the jejunum and ileum. This suggests that a difference exists between renal and intestinal handling of lysine and arginine in cystinuria.
Asunto(s)
Aminoácidos Diaminos/metabolismo , Calcio/metabolismo , Cistinuria/metabolismo , Absorción Intestinal , Riñón/metabolismo , Errores Innatos del Metabolismo de los Metales/metabolismo , Adulto , Calcio/orina , Genotipo , Heterocigoto , Humanos , Íleon/metabolismo , Yeyuno/metabolismo , Cálculos Renales , MasculinoRESUMEN
The renal clearance of cystine, lysine, ornithine, arginine, and glycine has been compared with the simultaneously determined glomerular filtration rate in nine cystinuric patients. Five were studied before and after stabilization on penicillamine therapy, two were studied only while taking penicillamine, and two were studied only in the absence of penicillamine administration. The renal clearances of cysteine-penicillamine and of penicillamine disulfide were also determined in the patients who were taking the drug. Amino acids were determined by quantitative ion exchange chromatography, and the reliability of the method has been evaluated in terms of its reproducibility and of the recovery of known amounts of amino acids added to plasma and to urine. The plasma levels of cystine and of the basic amino acids were less than normal in all the patients. Cysteine-penicillamine and penicillamine disulfide were cleared by the kidney at rates similar to that of cystine. Two of the patients had glycine clearances that were considerably above the normal value. The renal clearance of cystine exceeded the glomerular filtration rate in six of the nine patients. The results form a continuum from values approximately equal to the glomerular filtration rate to values about twice this amount. The renal clearances of cystine and of the basic amino acids vary independently of one another in the disease. The significance of these results is discussed in terms of the nature of the renal tubular transport defect that underlies the disorder.