Approach to Abnormal Liver Function Tests in Children

Approach to Abnormal Liver Function Tests in Children: Dr. Hossein Saneian, Pediatric Gastroenterologist Isfahan Medical School September ۲۰۲۵ The liver is a multifactorial organ that is involved in a number of vital excretory, synthetic, and metabolic functions. Although the term 'liver function test' is commonly used, it is not accurate because many tests, such as transaminases, do not measure liver function. Therefore, these tests should be referred to as 'liver enzyme tests', and 'liver function tests' should be the term used to measure the synthetic functions of hepatocytes, such as serum albumin and prothrombin time. In addition, common biochemical tests may be normal in a patient with liver disease (compensated cirrhosis) or abnormal in a healthy liver. This article reviews the various aspects of liver function tests and the approach to abnormal liver function tests. Abnormal liver tests are most often found in asymptomatic patients, as many routine screening test panels now include them. On the other hand, patients can have baseline fluctuations in serum aminotransferase levels. In a large population-based cross-sectional study, more than ۳۰% of adults with abnormal LFTs had normal tests upon retesting. The sensitivity and specificity of serum aminotransferases, which are used to differentiate between individuals with and without liver disease, depend on the cutoff values chosen to define an abnormal test. There is wide variation among laboratories in what is considered the upper limit of normal for alanine aminotransferase (ALT). The optimal cutoff value for ALT should be less than the upper limit of normal (ULN) used by many laboratories. The most sensitive cut-off for ALT in adults is ۲۹ for men (۲۹ to ۳۳), ۲۶ for boys, and ۲۲ for women and girls (۱۹ to ۲۵). Levels above these values should be evaluated for underlying liver disease. Most patients identified using lower cut-off values have only mild liver disease or no identifiable cause for the abnormal laboratory values. There are limitations to LFTs, including: ۱- A normal liver function test (LFT) does not guarantee that the patient is free of liver disease (e.g., compensated cirrhosis). ۲- These tests are not specific for liver function. ۳- These tests do not usually provide a specific cause, but are indicative of a liver disorder. Therefore, the clinical significance of any abnormal liver function test (LFT) must be interpreted on an individual patient basis. Tests that evaluate liver function can be divided into five categories: ۱- Those that