title: [Analysis of propionylcarnitine in blood and methylmalonic acid in urine of 162 patients with methylmalonic acidemia].
abstract: OBJECTIVE
  To analyze the levels of methylmalonic acid and methylcitrate in urine, propionylcarnitine (C3) in plasma and C3/acetylcarnitine (C2) of patients with methylmalonic acidemia (MMA) and explore their applications in the diagnosis of MMA.
  
  
  METHODS
  From December 2003 to March 2012, a total of 162 patients with MMA (MMA group) and 200 healthy children (control group) of Xinhua Hospital, Shanghai Jiaotong University School of Medicine were recruited. MMA patients with a definite classification were divided into 2 groups: isolate MMA group (n = 51) and MMA complicated with homocysteinemia group (n = 65). Gas chromatography-mass spectrometry was used to measure the urine levels of methylmalonic acid and methylcitrate and tandem mass spectrometry to measure the blood levels of free carnitine (C0), acylcarnitines and methionine (Met).
  
  
  RESULTS
  In the MMA group, the median levels of methylmalonic acid (259.10 (6.73 - 6429.28)), methylcitrate (4.39 (0 - 248.96)), C3 (8.52 (1.50 - 52.11) µmol/L) and C3/C2 (0.73(0.28 - 2.89)) were all higher than the upper limit values (0.2 - 3.6, 0 - 1.1, 0.50 - 4.00 µmol/L and 0.04 - 0.25 respectively). And they were all higher than those in the control group (0 (0 - 1.87), 0.10 (0 - 1.84), 1.40 (0.53 - 3.90) µmol/L, 0.10 (0.04 - 0.23), all P < 0.01). C3/C2 increased significantly in 15 patients while the C3 level remained normal. The median level of Met was normal in the isolate MMA group. But in patients with homocysteinemia, the level of 8.71 (0.68 - 31.95) µmol/L was below the reference value (10.00 - 35.00 µmol/L) and lower than that in the isolate MMA group (15.35 (4.18 - 59.50) µmol/L) and the control group (15.59 (10.20 - 34.68) µmol/L, all P < 0.05).
  
  
  CONCLUSIONS
  Significant increases in the urine level of methylmalonic acid and C3/C2 may be specific to MMA. Organic acid analyses of gas chromatography-mass spectrometry and acylcarnitines with tandem mass spectrometry are required for a definite diagnosis of this disorder. And repeated tests and genomic mutation analysis are necessary for patients with mildly abnormal biochemical indices.
authors.affiliation: Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
authors.forename: Sheng-nan
authors.initials: SN
authors.lastname: Wu
authors.forename: Lian-shu
authors.initials: LS
authors.lastname: Han
authors.forename: Jun
authors.initials: J
authors.lastname: Ye
authors.forename: Wen-juan
authors.initials: WJ
authors.lastname: Qiu
authors.forename: Hui-wen
authors.initials: HW
authors.lastname: Zhang
authors.forename: Xiao-lan
authors.initials: XL
authors.lastname: Gao
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiao-yan
authors.initials: XY
authors.lastname: Li
authors.forename: Hao
authors.initials: H
authors.lastname: Xu
authors.forename: Xue-fan
authors.initials: XF
authors.lastname: Gu
mesh_terms: D000108:Acetylcarnitine / Q000097:blood; D000293:Adolescent; D000328:Adult; D000592:Amino Acid Metabolism, Inborn Errors / Q000097:blood* / Q000652:urine*; D002331:Carnitine / Q000031:analogs & derivatives* / Q000097:blood; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008764:Methylmalonic Acid / Q000652:urine*; D053719:Tandem Mass Spectrometry; D055815:Young Adult
chemical_list: C003223:propionylcarnitine; D000108:Acetylcarnitine; D008764:Methylmalonic Acid; D002331:Carnitine