oksalat

Oksalat, or oxalate, is the dianion of oxalic acid, with the chemical formula C2O4^2−. In nature and in the human body it commonly occurs as salts such as calcium oxalate and sodium oxalate. Oxalate is partly derived from diet and partly formed in metabolism, and it is poorly metabolized and rapidly excreted by the kidneys.

Dietary sources high in oksalat include spinach, beet greens, rhubarb, nuts, tea, cocoa, and certain berries. Daily intake varies widely by diet. Oxalate can bind calcium to form calcium oxalate, the most common constituent of kidney stones.

In humans, gut absorption is limited, and oxalate is filtered by the kidneys and excreted in urine. The body has limited pathways to break down oxalate; some intestinal bacteria such as Oxalobacter formigenes can degrade oxalate, reducing absorption. Antibiotics can reduce these bacteria and increase oxalate absorption.

Excessive oxalate in urine (hyperoxaluria) can contribute to kidney stone formation (calcium oxalate stones) and nephrocalcinosis. Primary hyperoxaluria is a rare genetic disorder causing overproduction of oxalate; management includes hydration, dietary modification, calcium citrate to bind oxalate in the gut, and in some cases liver transplantation.