Very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency, a condition in which the body is unable to break down long-chain fatty acids properly, is the most common fatty acid oxidation disorder in Japan. Tandem mass spectrometry has been used in newborn screening (NBS), allowing the detection of patients with VLCAD deficiency even before symptoms manifest. However, tandem mass spectrometry has a high false positive rate. We investigated the clinical characteristics of patients with false positive results for tetradecenoyl acylcarnitine (C14:1). This case-control study used data collected between the 1st of January 2014 and the 31st of March 2019. The case group was defined as patients having levels of both C14:1 and C14:1/C2 ratio higher than cut-off levels in the first newborn mass screening, who were eventually diagnosed as false positives by attending doctors at Kobe University Hospital, Palmore Hospital, or Kakogawa Central City Hospital in Japan. The control group comprised 100 patients randomly selected from the three facilities. The false positive group included 17 cases, and the control group contained 300 patients. The demographics of each group did not show any significant differences in sex, body weight at birth, Cesarean section rate, complete breastfeeding rate, or the number of feedings per day. However, the change in body weight at the sampling day of NBS in the false positive and control groups was −10.2%, and − 4.6%, respectively, showing a statistically significant difference (p < 0.01). In addition, body weight gain at the one-month medical checkup was 38.9 g/day in the false positive group and 44.1 g/day in the control group (p < 0.05). An elevation of C14:1 carnitine has been reported in situations involving the catalysis of fatty acid. Therefore, patients with severe body weight loss might be associated with poor sucking or poor milk supply, which might cause a false positive elevation of C14:1 and C14:1/C2. In suspected VLCAD deficiency, attending doctors should pay attention to body weight changes recorded during newborn mass screening.

超长链酰基辅酶A脱氢酶（VLCAD）缺乏症是人体无法正常分解长链脂肪酸的疾病，是日本最常见的脂肪酸氧化疾病。串联质谱已用于新生儿筛查（NBS），甚至在症状出现之前就可以检测到VLCAD缺乏症的患者。但是，串联质谱具有较高的假阳性率。我们调查了十四碳酰酰基肉碱（C14：1）假阳性结果的患者的临床特征。该病例对照研究使用了2014年1月1日至2019年3月31日之间收集的数据。病例组的定义为C14：1和C14：1 / C2的水平均高于临床研究中的临界水平。第一次新生儿筛查 最终被日本神户大学医院，帕尔莫瑞医院或日本加古川中央城市医院的医生诊断为假阳性。对照组包括从三个设施中随机选择的100名患者。假阳性组包括17例，对照组包括300例。每组的人口统计资料在性别，出生时体重，剖腹产率，完全母乳喂养率或每天的喂养次数方面均无显着差异。但是，假阳性组和对照组在NBS采样当天的体重变化分别为-10.2％和-4.6％，显示出统计学上的显着性差异（对照组包括从三个机构中随机选择的100名患者。假阳性组包括17例，对照组包括300例。每组的人口统计资料在性别，出生时体重，剖腹产率，完全母乳喂养率或每天的喂养次数方面均无显着差异。但是，假阳性组和对照组在NBS采样当天的体重变化分别为-10.2％和-4.6％，显示出统计学上的显着性差异（对照组包括从三个机构中随机选择的100名患者。假阳性组包括17例，对照组包括300例。每组的人口统计资料在性别，出生时体重，剖腹产率，完全母乳喂养率或每天的喂养次数方面均无显着差异。但是，假阳性组和对照组在NBS采样当天的体重变化分别为-10.2％和-4.6％，显示出统计学上的显着性差异（或每天的喂食次数。但是，假阳性组和对照组在NBS采样当天的体重变化分别为-10.2％和-4.6％，显示出统计学上的显着性差异（或每天的喂食次数。但是，假阳性组和对照组在NBS采样当天的体重变化分别为-10.2％和-4.6％，显示出统计学上的显着性差异（p  <0.01）。此外，假阳性组在1个月体检中的体重增加为38.9 g /天，对照组为44.1 g /天（p  <0.05）。据报道，在涉及脂肪酸催化的情况下，C14：1肉碱水平升高。因此，体重严重减轻的患者可能与吮吸不良或牛奶供应不足有关，这可能导致C14：1和C14：1 / C2的假阳性升高。如果怀疑VLCAD缺乏，主治医生应注意新生儿体检时记录的体重变化。