Gutierrez A, Alvestrand A, Qureshi G A, Bergström J
Department of Renal Medicine, Karolinska Institute, Huddinge University Hospital, Stockholm, Sweden.
J Intern Med. 1992 Aug;232(2):129-32. doi: 10.1111/j.1365-2796.1992.tb00561.x.
Urinary excretion of 3-methylhistidine has been proposed as an index of internal protein breakdown provided that the intake of exogenous 3-methylhistidine (meat) is excluded. To evaluate the potential use of 3-methylhistidine in the metabolic assessment of patients with advanced renal failure, we studied a group of 11 patients with markedly reduced renal function who were put on a meat-free diet (the protein intake was kept constant). Steady-state plasma concentration and urinary excretion of 3-methylhistidine were not achieved until 14 d after exclusion of meat from the diet. At that time the plasma concentration and urinary excretion of 3-methylhistidine had decreased by 43% and 60%, respectively. We conclude that the delay in reaching steady state makes the clinical use of urinary excretion of 3-methylhistidine in patients with advanced renal failure unpracticable as an index of protein breakdown. The exclusion of meat also resulted in a continuous decrease in the plasma level and urinary excretion of creatinine, with the result that plasma creatinine or its reciprocal become misleading for evaluation of changes in renal function until a new steady state has been reached.
如果排除外源性3-甲基组氨酸（肉类）的摄入，尿中3-甲基组氨酸的排泄已被提议作为体内蛋白质分解代谢的一个指标。为了评估3-甲基组氨酸在晚期肾衰竭患者代谢评估中的潜在用途，我们研究了一组11名肾功能明显降低的患者，他们采用无肉饮食（蛋白质摄入量保持恒定）。从饮食中排除肉类后14天，3-甲基组氨酸的稳态血浆浓度和尿排泄量才达到。此时，3-甲基组氨酸的血浆浓度和尿排泄量分别下降了43%和60%。我们得出结论，达到稳态的延迟使得在晚期肾衰竭患者中，将尿中3-甲基组氨酸排泄作为蛋白质分解代谢指标的临床应用不切实际。排除肉类还导致血浆肌酐水平和尿肌酐排泄持续下降，结果是在达到新的稳态之前，血浆肌酐或其倒数对于评估肾功能变化会产生误导。
