Abstract:

Objective  To analyze clinical and pathological characteristics of mitochondrial myopathy (MM) in 15 patients, and to study the value of simplified serum lactic acid exercise test in the screening of mitochondrial myopathy.  Methods  A total of 15 patients with mitochondrial myopathy diagnosed clinically and pathologically, 11  patients with other muscular diseases (OM), and 21 normal controls were collected. All subjects went up and down stairs for 5 min with medium effort. Blood samples for serum lactic acid detection were collected from all subjects before exercise, immediately after exercise and 10 min after exercise. Serum lactic acid levels were compared among 3 groups and among 3 time points.  Results  Patients with mitochondrial myopathy mainly presented as paroxysmally progressive muscular   soreness and weakness. Histopathological examination showed there were 8 cases with the proportion of ragged red fibers (RRF) more than 5%. Serum lactic acid level before exercise, immediately after exercise and 10 min after exercise were (3.57 ± 1.88), (10.98 ± 4.84) and (7.87 ± 4.38) mmol/L in MM group, (1.89 ± 0.98), (6.05 ± 4.07) and (4.13 ± 3.14) mmol/L in OM group, (1.91 ± 0.53), (3.37 ± 1.22) and (2.52 ± 0.89) mmol/L in control group. Serum lactic acid level in MM group was significantly higher than that in control and OM groups before exercise (P = 0.000, 0.001), immediately after exercise (P = 0.000, 0.001), and 10 min after exercise (P = 0.000, 0.003). Serum lactic acid level in OM group was significantly higher than that in control group immediately after exercise (P = 0.042). Serum lactic acid level in 3 groups immediately after exercise (P = 0.000, 0.000, 0.003) and 10 min after exercise (P = 0.000, 0.000, 0.013) was significantly higher than that before exercise. Serum lactic acid level immediately after exercise was significantly higher than that 10 min after exercise in 3 groups (P = 0.000, 0.000, 0.003). Serum lactic acid level had most obvious elevation in MM group, while had flattest elevation in control group.  Conclusions  Simplified serum lactic acid exercise test is useful in the  creening of mitochondrial myopathy, especially in primary hospitals.

Key words: Mitochondrial myopathies, Pathology, Lactic acid

摘要：

目的 总结线粒体肌病（MM）的临床病理学特点，探讨简易乳酸运动试验在线粒体肌病筛查中的价值。 方法 分析经临床和病理学明确诊断的15 例线粒体肌病患者临床病理学特点。15 例线粒体肌病患者、11 例其他肌肉疾病（OM）患者和21 例正常对照者行简易乳酸运动试验，于运动前、运动后即刻和运动后10 min 检测血清乳酸水平。 结果 线粒体肌病患者主要表现为发作性加重的肌肉酸痛无力，8 例组织病理学显示破碎红纤维比例> 5 %。简易乳酸运动试验显示：MM 组运动前、运动后即刻和运动后10 min 血清乳酸为（3.57 ± 1.88）、（10.98 ± 4.84）和（7.87 ± 4.38）mmol/L，OM 组为（1.89 ± 0.98）、（6.05 ± 4.07）和（4.13 ± 3.14)mmol/L，对照组为（1.91 ± 0.53）、（3.37 ± 1.22）和（2.52 ± 0.89）mmol/L。MM 组运动前（P = 0.000，0.001）、运动后即刻（P = 0.000，0.001）和运动后10 min（P = 0.000，0.003）血清乳酸水平均高于对照组和OM 组，OM 组仅运动后即刻血清乳酸水平高于对照组（P = 0.042）；3 组运动后即刻（P =0.000，0.000，0.003）和运动后10 min（P = 0.000，0.000，0.013）血清乳酸水平均高于运动前，运动后即刻亦高于运动后10 min（P = 0.000，0.000，0.003）。3组血清乳酸水平升高趋势尤以MM 组最显著，对照组最低平。 结论 简易乳酸运动试验简单易行，可以作为基层医院对线粒体肌病的初筛试验。

关键词: 线粒体肌病, 病理学, 乳酸