背景:肉碱对于将长链脂肪酸运输到线粒体中至关重要,并通过长链脂肪酸的β-氧化促进能量代谢。虽然肉碱也存在于外周血中,总肉碱的98%储存在肌肉组织中。伴有肌肉萎缩的神经肌肉疾病很可能导致继发性肉碱缺乏,由于体内储存的肉碱总量减少。
方法:一名8岁的日本男孩患有福山型先天性肌营养不良并伴有严重的精神运动迟钝,患有吞咽困难,并从1岁开始通过胃造口管喂养。7岁开始定期口服肉碱补充剂(5mg/kg/d左卡尼汀),将血清肉碱值增加到正常范围(血清总肉碱浓度,58.5-60.9μmol/L;酰基肉碱浓度,45.8-55.0μmol/L;游离肉碱浓度,5.9-12.7μmol/L)。他发烧了,呕吐,8岁时胃肠道出血。他陷入昏迷,12小时后去了急诊室。低血糖症和低肉碱血症(血清总肉碱浓度,3.7μmol/L;酰基肉碱浓度,2.9μmol/L;游离肉碱浓度,0.8μmol/L;酰基与游离肉碱之比,3.6)被观察到,他被发现尿酮体呈阴性。
结论:伴有肌肉萎缩的神经肌肉疾病可能导致急性肉碱缺乏,即使发病前血清肉碱浓度在正常范围内。在病假期间,可能有必要修改患者的治疗方法,例如增加肉碱的口服补充和静脉内给药。
Carnitine is essential for transporting long-chain fatty acids into mitochondria and promotes energy metabolism via β-oxidation of long-chain fatty acids. Although
carnitine is also present in the peripheral blood, 98% of total
carnitine is stored in muscle tissue. Neuromuscular diseases accompanied by muscle atrophy are likely to lead to secondary carnitine deficiency, owing to the reduced amount of total
carnitine stored in the body.
An 8-y-old Japanese boy with Fukuyama-type congenital muscular dystrophy accompanied by severe psychomotor retardation had been constantly bedridden, suffered from dysphagia, and had been fed through a gastrostomy tube since the age of 1 y. Regular oral carnitine supplementation (5 mg/kg/d of levocarnitine) was initiated at the age of 7 y, which increased serum
carnitine value to within the normal range (serum total
carnitine concentration, 58.5-60.9 μmol/L; acylcarnitine concentration, 45.8-55.0 μmol/L; free carnitine concentration, 5.9-12.7 μmol/L). He developed a fever, vomiting, and gastrointestinal bleeding at the age of 8 y. He fell into a coma and visited an emergency room 12 h later. Hypoglycemia and hypocarnitinemia (serum total carnitine concentration, 3.7 μmol/L; acylcarnitine concentration, 2.9 μmol/L; free
carnitine concentration, 0.8 μmol/L; acyl-to-free
carnitine ratio, 3.6) were observed, and he was found to be negative for urinary ketone bodies.
Neuromuscular diseases accompanied by muscle atrophy may lead to acute carnitine deficiency, even if the serum
carnitine concentration is within the normal range before onset. During sick days, it may be necessary to modify a patient\'s treatment, such as increasing both oral supplementation and intravenous administration of carnitine.