title: Characterization of creatinine error in ketotic patients. A prospective comparison of alkaline picrate methods with an enzymatic method.
abstract: Creatinine measurement by alkaline picrate reagents is subject to positive interference by acetoacetate. Enzymatic reagents avoid this interference and have been adapted to instruments such as the Ektachem-400 (Kodak). By documenting the discrepancy between alkaline picrate and Ektachem determinations for creatinine, the authors prospectively identified ketotic patients in whom the presence of ketones was responsible for a significant creatinine error. During their three-month survey, they identified 50 such ketotic inpatients. Those admitted to the medicine service represented almost 5% of all medicine admissions over this time. Of the total specimens, the mean discrepancy was 14 +/- 8 mg/L with a range of 4-44 mg/L. The greater the ketosis, the greater the discrepancy. Two-thirds of the samples were normal on the Ektachem but greater than normal by picrate methods. In addition to diabetes or ethanol abuse, 17% of the ketotic patients had severe or terminal illness that was generally associated with malnutrition.
mesh_terms: D000090:Acetoacetates / Q000097:blood; D000138:Acidosis / Q000097:blood*; D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood*; D005260:Female; D006801:Humans; D007662:Ketosis / Q000097:blood*; D008297:Male; D008722:Methods; D008875:Middle Aged; D010851:Picrates; D011446:Prospective Studies; D013997:Time Factors
chemical_list: D000090:Acetoacetates; D010851:Picrates; C016635:acetoacetic acid; D003404:Creatinine