甲基丙二酸尿症的肾脏损害五例报告

Renal impairment in patients with methylmalonic aciduria: a review of five cases

目的探讨甲基丙二酸尿症肾脏损害的临床特点,以期提高认识,达到早期诊断、早期干预和改善预后的目的。方法对尿有机酸分析确诊的5例有肾脏受累的甲基丙二酸尿症患者的临床表现、生化特点以及诊疗情况进行分析。结果5例患者均有不同程度的肾小球及肾小管受累表现,其中2例有肾功能不全,肾脏受累可先于、同时或晚于神经系统受累。5例均为钴胺素反应型,治疗后肾脏损害得到不同程度的改善。结论对于不明原因的血尿、蛋白尿、肾功能下降的患者,特别应注意有无合并神经系统体征,尽早行代谢病筛查及尿有机酸分析,以免延误诊断。

Objective The renal impairment in children with methylmalonic aciduria has seldom been reported. To improve knowledge in this aspect, clinical data of five cases with methylmalonic aciduria with renal involvement were analyzed and the results are reported in this paper, which may be of some help in early diagnosis, treatment and in achieving favorable prognosis. Methods Urine methylmalonic acid was measured by gas chromatography-mass spectrometry analysis, if the content exceeded the normal range and vitamin B12 deficiency was excluded, the diagnosis of methylmalonic aciduria was confirmed. Homocysteine in plasma was also measured with fluorescence polarization immunoassay to make sure if concomitant homocysteinemia existed. From January 2002 to January 2005, five patients who had renal impairment were diagnosed as methylmalonic aciduria by urinary organic acid analysis. Among them, three were male, two were female, aged from seven months to 26 years, with average of 13 years. Three were presented to pediatric nephrology clinic with hematuria, proteinuria or edema, the other two were presented to pediatric neurology clinic first for psychomotor retardation. Their clinical features, laboratory findings, treatment regimens and prognosis were analyzed and summarized. Results All the five patients with methylmalonic aciduria were found to have various degrees of renal impairment, manifested as hematuria or proteinuria. Among them, two cases had gross hematuria and three had microscopic hematuria. Edema was found in two cases and hypertension occurred in one case. Early indicators of renal damage, such as microalbunminuria, N-acetyl-beta-D glucosaminidase, transferrin and ct-microglobulin showed glomerular and tubular dysfunction. Clinically nephrotic syndrome was diagnosed in one case, the other four cases were diagnosed as glomerulonephritis, and two cases had renal failure. Renal biopsy was performed in one case, tubulointerstitial damage and mesangial proliferation appeared. Mental retardation and psychomotor disorder were chief nervous system complaints. Leukodystrophy was the main finding on imaging. Megaloblastic anemia was found in three cases. All the five patients were cobalamin-responsive type. Renal impairment was alleviated following treatment, edema and gross hematuria as well as hypertension disappeared later, proteinuria diminished, renal function improved, central nervous system symptoms and hematopoietic function ameliorated. Conclusion In patients with hematuria, proteinuria or renal failure of unknown origin, metabolic screening and urinary organic acid analysis should be performed as early as possible to confirm the diagnosis.