25hidroxi

25hidroxi refers to the chemical process involving the hydroxylation of a compound at the 25th carbon position. This term is most commonly associated with vitamin D metabolism, where the liver converts vitamin D3 (cholecalciferol) into 25-hydroxyvitamin D (25(OH)D), also known as calcifediol. This hydroxylation is a crucial step in the activation pathway of vitamin D, as it represents the primary circulating form of the vitamin in the bloodstream and is often measured to assess vitamin D status in the body.

The enzyme responsible for this conversion is vitamin D-25-hydroxylase, primarily found in the liver. Once produced, 25(OH)D can be further hydroxylated in the kidneys to form the biologically active form, 1,25-dihydroxyvitamin D (calcitriol), which regulates calcium and phosphate metabolism, bone mineralization, and immune function.

Measurement of 25(OH)D levels in blood is a standard clinical test to evaluate vitamin D deficiency, insufficiency, or sufficiency. Levels are typically reported in nanomoles per liter (nmol/L) or nanograms per milliliter (ng/mL), with varying thresholds for deficiency depending on clinical guidelines. For example, levels below 20 ng/mL (50 nmol/L) are often considered deficient, while levels between 20 and 30 ng/mL (50–75 nmol/L) may indicate insufficiency.

In addition to its role in vitamin D metabolism, the term *25hidroxi* can appear in other biochemical contexts, such as the hydroxylation of steroids or other lipid-soluble molecules, though this is less common. Proper vitamin D status is essential for maintaining bone health, immune function, and overall physiological balance.