To the Editor.—
Retinoids (13-cis-retinoic acid or isotretinoin, and trans-retinoic acid or tretinoin) are therapeutic antiacne agents that affect sebaceous gland function and keratinization. Recently, it has been determined that both trans-retinoic acid and 13-cis-retinoic acid are normal constituents of human serum.1 Circulating 13-cis-retinoic acid is derived from endogenous isomerization of trans-retinoic acid, while trans-retinoic acid is related to dietary intake and originates as a by-product of retinol metabolism.1 We evaluated whether endogenous plasma retinoids protect against acne determining if lower values are present in affected patients. Simultaneously, we measured other factors that might be involved in the pathogenesis of acne.
Materials and Methods.—
The study population comprised 19 individuals with acne (ages, 21 to 43 years; median age, 25 years) and 19 non-acne control subjects matched by age (27 to 42 years; median age, 26), sex, and