title: Role of homocysteine, cystathionine and methylmalonic acid measurement for diagnosis of vitamin deficiency in high-aged subjects.
abstract: BACKGROUND
  Intracellular B-vitamin and folate deficiency indicated by hyperhomocysteinemia is very frequent in the elderly population. Hyperhomocysteinemia increases the risk of atherothrombotic diseases and neuropsychiatric complications. Our aim was to evaluate the prevalence of increased serum metabolite concentrations in subjects of a higher age, and whether the measurement of metabolite concentrations is more effective in diagnosing B-vitamin deficiency than mere homocysteine.
  
  
  METHODS
  Homocysteine (HCY), cystathionine (CYS) and methylmalonic acid (MMA) were investigated in serum together with vitamin B-12, B-6 and folate in 90 high-aged subjects (85-102 years), 92 seniors (65-75 years), and in 50 younger subjects (19-50 years).
  
  
  RESULTS
  Elderly subjects (high-aged and senior) had elevated serum concentrations of metabolites. High-aged subjects had a higher frequency of pathological increases than seniors: HCY 62% vs. 24%; MMA 62% vs. 23%; CYS 81% vs. 36%. Folate and vitamin B-6 concentrations were significantly decreased in both elderly groups; vitamin B-12 was only decreased in high-aged subjects. Utilising vitamin B-6, B-12 and folate for diagnosis of intracellular vitamin deficiency, the rate was 30% in seniors and 55% in high aged subjects. However, utilising the metabolites (HCY, MMA and CYS) for the diagnosis of intracellular vitamin deficiency, there was a distinctly increased rate of 55% in seniors respective to 90% in high-aged subjects. Backward multiple regression analysis revealed that only folate, MMA, creatinine and age were independent variables influencing the HCY concentration. Furthermore, the MMA concentration was significantly and independently influenced by folate, vitamin B-12, HCY and creatinine, and the serum concentration of CYS by vitamin B-12, creatinine and age.
  
  
  CONCLUSIONS
  The metabolites HCY, MMA and CYS are sensitive indicators diagnosing impaired remethylation of homocysteine to methionine with parallel activation of catabolic pathway. Compared to mere HCY or B-vitamins in serum, the efficiency of diagnosing a disturbed HCY metabolism increases very much in utilising the metabolites HCY, MMA and CYS. For differential diagnosis, parallel measurement of folate and creatinine is recommended. The early and correct diagnosis of B-vitamin deficiency in elderly subjects is of high clinical relevance.
authors: University Hospital of the Saarland, Homburg/Saar, Germany. kchwher@med-rz.uni-sb.de
authors: W
authors: W
authors: Herrmann
authors: H
authors: H
authors: Schorr
authors: M
authors: M
authors: Bodis
authors: J P
authors: JP
authors: Knapp
authors: A
authors: A
authors: Müller
authors: G
authors: G
authors: Stein
authors: J
authors: J
authors: Geisel
mesh_terms: D000328:Adult; D000368:Aged; D003540:Cystathionine / Q000097:blood*; D005260:Female; D005492:Folic Acid / Q000097:blood; D005494:Folic Acid Deficiency / Q000097:blood / Q000175:diagnosis*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008297:Male; D008764:Methylmalonic Acid / Q000097:blood*; D008875:Middle Aged; D008956:Models, Chemical; D011736:Pyridoxine / Q000097:blood; D014805:Vitamin B 12 / Q000097:blood; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000175:diagnosis*; D026681:Vitamin B 6 Deficiency / Q000097:blood / Q000175:diagnosis*
chemical_list: D006710:Homocysteine; D003540:Cystathionine; D008764:Methylmalonic Acid; D005492:Folic Acid; D011736:Pyridoxine; D014805:Vitamin B 12