The reaction catalysed by arginase cleaves arginine to urea. Ornithine may be converted into arginine through Krebs-Henseleit urea cycle. The defect in urea synthesis is manifested by raised blood and cerebrospinal fluid arginine levels. A low protein diet would be helpful to correct it. Catabolism of six-carbon amino acid argine form ketoglutarate. Arginine serves as the formamidine donor for creatine biosynthesis, and via ornithine, participates in polyamine biosynthesis.

Arginine vasopression is suggested in treatment of antidiuretic hormone deficiency.

The metabolism of arginine results in formation of urea, synthesis of creatine (guanidoacetic acid), synthesis of ornithine, and formation of guanidobutyric acid in the brain, in separate reactions. The arginine by hydrochroride stimulates growth hormone release up to three times the base level. It is therefore administered intravenous to check the normal/deficient hormone release.

Supplemental arginine, a conditional-essential amino acid required during periods of growth, enhances T-lymphycyte response and increase helpher T-cell numbers in surgical patients.

It is required for formation of proteins like collagen and elastin, and other vitals like haemoglobin, insulin, and glucagons. It is main component of male seminal fluid. It gives normal growth, promotes immune system, and works as a vital part of urea cycle in the liver for detoxification and elimination of urea. The deficiency causes disorder in carbohydrates metabolism. It should be avoided in viral infections.

It is available in plenty in dry yeast, human milk, cheese, pork, grapes, banana, water melon seeds, piyal seeds, cucumber, cauliflower, tapioca, radish, cabbage, pumpkin leaves, peas, lentil rice and wheat. There is no scientific conclusion of RDA for arginine at present. However up to 2 gm is given on any empty stomach for therapeutic purposes.