title: Risk factors for methotrexate-induced abnormal laboratory monitoring results in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To determine risk factors for methotrexate (MTX)-induced hepatic and hematologic laboratory abnormalities in patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Measurements of aspartate aminotransferase (AST), white blood cell counts, and platelet counts were collected in a database of patients with RA receiving MTX from 1991 through 2002. Potential risk factors for toxicity were recorded on each patient.
  
  
  RESULTS
  Four hundred and eighty-one patients were followed for 2,323 person-years of MTX exposure. MTX was discontinued permanently because of abnormal laboratory test results in 22 patients (4.6%), the majority of whom (17/22, 77%) had elevated AST values. The body mass index (BMI) was significantly higher in those patients where MTX was permanently discontinued than in those in whom it was not (p < 0.03). Independent predictors of a significantly higher percentage of abnormal AST values were lack of folate supplementation (p < 0.001) and untreated hyperlipidemia (p < 0.02). Of the 17 patients in whom MTX was discontinued permanently because of an elevated AST value, 11/17 (65%) had either lack of folate supplementation or untreated hyperlipidemia. Hypoalbuminemia correlated independently with an increased percentage of abnormal platelet counts (p < 0.03).
  
  
  CONCLUSIONS
  Lack of folate supplementation, untreated hyperlipidemia, and elevated BMI identified patients receiving MTX at risk for transaminase elevation, and low serum albumin was a risk factor for thrombocytopenia. Nonalcoholic fatty liver disease could be the underlying risk factor for transaminase elevation in patients with hyperlipidemia and obesity.
authors.affiliation: Division of Rheumatology and Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Kent
authors.forename: Harvinder S
authors.initials: HS
authors.lastname: Luthra
authors.forename: Clement
authors.initials: C
authors.lastname: Michet
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000453:epidemiology*; D001219:Aspartate Aminotransferases / Q000097:blood; D015331:Cohort Studies; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use; D006801:Humans; D006949:Hyperlipidemias / Q000453:epidemiology; D015994:Incidence; D008103:Liver Cirrhosis / Q000139:chemically induced* / Q000453:epidemiology; D008297:Male; D008727:Methotrexate / Q000009:adverse effects*; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D018501:Antirheumatic Agents; D005492:Folic Acid; D001219:Aspartate Aminotransferases; D008727:Methotrexate