Lysinemia is a rare genetic disorder that causes an abnormal buildup of the amino acid lysine in the body. Synonyms for lysinemia include hyperlysinemia and lysine intolerance. Hyperlysinemia refers to conditions where lysine levels are elevated in the blood, whereas lysine intolerance is a term used to describe individuals who experience adverse reactions to lysine-containing foods or supplements. Other related conditions may include lysinuric protein intolerance, which is a disorder where lysine and other amino acids cannot be metabolized properly, and saccharopinuria, which is a disorder where the body cannot break down lysine and other amino acids. Regardless of the term used, lysinemia is a serious condition that requires proper diagnosis and management.