Clinicians sometimes order liver tests as part of a screening examination or general work-up.
Current guidelines do not recommend routine retesting of abnormal results in asymptomatic patients.
Dr Mariana Lazo and colleagues from Maryland, USA characterized the magnitude of intraindividual variability of liver test results.
In addition, the researchers determined the proportion of adults with persistently elevated levels after 1 positive test.
|If retested, more than 30% of adults with elevated bilirubin levels would be reclassified as normal|
|Annals of Internal Medicine|
The team assessed the National Health and Nutrition Examination Survey III using the First and Second Examinations from 1988 to 1994.
The analysis included 1,864 men and women age 18 years or older living in the United States.
Repeated measurements of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, -glutamyltransferase, and bilirubin using National Health and Nutrition Examination Survey III cutoffs for normal levels were undertaken.
The research team observed that 38% of adults with initially elevated bilirubin levels had normal levels at the second examination.
The team found these proportions were 36%, 31% for aspartate aminotransferase, and alanine aminotransferase, respectively.
The proportions for alkaline phosphatase, and -glutamyltranferase were 17% and 12%, respectively.
More than 95% of initially normal results remained normal.
The researchers found the results did not differ by alcohol consumption; Hepatitis A, B, or C serologic status; recent infection; body mass index; or sociodemographic characteristics.
Intraindividual variability was significantly higher for bilirubin, and alanine aminotransferase than for aspartate aminotransferase, -glutamyltransferase, and alkaline phosphatase.
However, the team reported that only 2 measurements were available, and complete liver disease history was lacking.
Dr Lazo's team concluded, "If retested, more than 30% of adults with elevated aspartate aminotransferase, alanine aminotransferase, or bilirubin levels would be reclassified as normal."
"Clinicians should be aware of the high intraindividual variability in common liver tests, and practice guidelines should explicitly recommend retesting of asymptomatic individuals with abnormal liver test results."