Mirrors ALP so can be used to confirm if a rise in ALP is of hepatic origin
Raised with alcohol abuse and enzyme-inducing drugs
Extravascular haemolysis results in breakdown of Hb → globulin (further broken down into amino acids) + haem (further broken down into bilirubin). This unconjugated bilirubin is then conjugated by the liver so it can be excreted in bile. In advanced liver disease, the liver retains its ability to conjugate bilirubin, but it cannot excrete it.
Conjugated hyperbilirubinaemia: increased ‘direct’ bilirubin (direct = directly related to the liver)
Biliary obstruction (cholestasis)
Functional liver tests
Albumin makes up more than half of the total protein in the blood. The remainder is made up by globulins (other blood proteins) which include α1-globulins (α1-antitrypsin), α2-globulins (α2-macroglobulin, haptoglobin), β-globulins (complement, transferrin), and γ-globulins (immunoglobulins). Albumin is synthesised by the liver and has a half-life of around 20 days. Hence, changes in levels happen over weeks.
↓albumin + ↓total protein = cirrhosis, nephrotic syndrome, chronic inflammation, protein-losing enteropathy, alcoholism, protein malnutrition/malabsorption
↓albumin + normal total protein = infection (albumin is a negative acute phase protein)
↓albumin + ↑ total protein = myeloma, Waldenström’s macroglobulinaemia, autoimmune conditions, infection, chronic inflammation
PT/INR depend on clotting factors and fibrinogen which are synthesised by the liver. Some clotting factors have short half-lives (e.g. 6-8 hours) so changes can occur rapidly.