steroid

Steroid is a broad class of organic compounds characterized by a common core structure of four fused rings known as the cyclopentanoperhydrophenanthrene nucleus. They include natural hormones such as glucocorticoids, mineralocorticoids, estrogens, and androgens, as well as synthetic compounds used in medicine and industry. Steroids originate in biological pathways from cholesterol and are produced in the adrenal glands, gonads, and liver, with synthesis and metabolism varying by tissue.

Mechanism of action typically involves intracellular or membrane-associated receptors. Genomic effects arise when steroid molecules diffuse into cells and bind to nuclear receptors, altering gene transcription and protein synthesis. Non-genomic actions can occur rapidly through membrane-associated signaling pathways. The resulting physiological effects are diverse, influencing metabolism, immune function, development, and reproduction.

Medical use includes corticosteroids (examples: prednisone, dexamethasone, hydrocortisone) for anti-inflammatory and immunosuppressive purposes, and mineralocorticoids (such as fludrocortisone) for fluid and electrolyte balance. Sex steroids, including estrogens, progestogens, and androgens, are used in hormone replacement therapy and in various birth control formulations. Anabolic steroids, synthetic derivatives of testosterone, may be prescribed for certain conditions causing muscle loss or androgen deficiency, though their use is tightly regulated due to safety concerns.

Risks and side effects vary by type and duration but commonly include immune suppression, osteoporosis, mood changes, metabolic effects, and potential organ toxicity. Long-term systemic corticosteroid use can cause Cushingoid features, weight gain, and glucose intolerance; excessive androgen activity can cause virilization or hormonal imbalances, especially in youth.

Regulation and public health issues include restrictions on non-medical use, monitoring for adverse effects, and bans on performance-enhancing use in competitive sports.