Some routine blood tests only detect liver damage and are not accurate enough to show whether the liver functions at an optimal level, explains Liver Doctor. These tests may, however, give accurate results in cases of mild liver diseases.
A blood test shows the levels of specific chemicals produced by the liver to know whether it functions normally, notes WebMD. The test measures proteins such as serum and albumin. If the levels of these proteins have reduced in the blood, the patient may have a liver disease. The test also measures partial thromboplastin, which indicates blood-clotting factors in the liver.