6β,11β,17,21-Tetrahydroxypregn-4-ene-3,20-dione, commonly known as 6β-Hydroxyhydrocortisone, is a specific stereoisomer and a metabolite of hydrocortisone (cortisol). It is a pregnane steroid featuring hydroxyl groups at the 6β, 11β, 17, and 21 positions, along with a ketone at the 3-position. Its CAS number is 53-35-0. This compound is primarily used as a reference standard in pharmaceutical analysis. It serves as a specified impurity standard for hydrocortisone and related corticosteroid drug substances and products. Its role is critical in analytical method development, validation, and quality control to monitor and control impurity levels, ensuring the safety and efficacy of corticosteroid medications. As a metabolite, it is also of interest in pharmacokinetic and metabolic studies of hydrocortisone. It is supplied as a high-purity chemical reference material for use in techniques such as HPLC and LC-MS.