title: Elevated serum homocysteine as a predictor for vitamin B12 or folate deficiency.
abstract: Tissue deficiency of vitamin B12 and folate results in an increase in serum homocysteine (sHcy). We have measured sHcy in patients with reduced serum vitamin B12 and/or red cell folate (RCF) to determine its usefulness as a discriminant for the diagnostic interpretation of reduced vitamin levels. Of 3846 patients who had serum vitamin B12 and RCF assayed, 335 (9%) had reduced vitamin levels. Multivariate analysis showed a significant association between sHcy and serum creatinine (p = 0.0001), positive intrinsic factor (IF) antibody or neutrophil hypersegmentation (NHS) (p = 0.001), increased MCV (p = 0.014) and low RCF (p = 0.025) but no relationship with the level of serum vitamin B12 or haemoglobin. After censoring the patients with renal impairment (n = 54), the distribution of the remaining 72 patients with elevated sHcy was 37/151 (25%) with low serum vitamin B12 with or without low RCF and 35/130 (27%) with low RCF alone. sHcy correctly identified response to vitamin therapy in 33/35 (94%) patients who had adequate parameters to assess response. The positive predictive values of IF antibody/NHS, macrocytosis and/or low RCF for elevated sHcy were 100% and 34% respectively. Twenty-four percent of patients with a low serum vitamin B12 and elevated sHcy had no abnormal haematologic parameters as determined by the routine laboratory staff. These data suggest that the usefulness of measuring sHcy in a routine diagnostic setting is limited and a careful review of the peripheral blood for macrocytosis and NHS plus determination of RCF may be a more cost-effective process than sHcy assay in most instances to determine the presence of tissue deficiency.
authors.affiliation: Haematology Unit, Alfred Group of Hospitals Pathology Service, Alfred Hospital, Prahran, Victoria, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Curtis
authors.forename: R
authors.initials: R
authors.lastname: Sparrow
authors.forename: L
authors.initials: L
authors.lastname: Brennan
authors.forename: M B
authors.initials: MB
authors.lastname: Van der Weyden
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004912:Erythrocytes / Q000737:chemistry; D005260:Female; D005494:Folic Acid Deficiency / Q000175:diagnosis*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D014806:Vitamin B 12 Deficiency / Q000175:diagnosis*
chemical_list: D006710:Homocysteine