n. 1  A nucleic acid that carries the genetic information in cells and some viruses, consisting of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine.
Less than 1 percent of patients with normal results on liver function tests before taking extended-release niacin tablets have elevated liver enzyme values (more than three times the reference range) after niacin is started.
High liver enzymes are one of the more frequent findings at a routine doctor visit. Potentially indicating liver damage, high liver enzymes are detected by a simple blood test. While liver enzymes are usually found in the liver, damage to this important organ causes the enzymes to leak into the bloodstream. The two liver enzymes that are the most straight-forward to test for and evaluate are aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Normal, or healthy ranges for these liver enzymes are: 1  AST = 5 to 40 units per liter of serum. 2  ALT = 7 to 56 units per liter of serum.