Steroid


Steroid
: A large group of chemical substances related in structure to one another and each containing the same chemical skeleton (a tetracyclic cyclopenta[a]phenanthrene skeleton). Many hormones, body constituents, and drugs are steroids. Examples: drugs used to relieve swelling and inflammation such as prednisone, vitamin D, and the sex steroids such as testosterone.
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1. Pertaining to the steroids. SYN: steroidal. Cf.:steroids. 2. One of the steroids. SYN: sterid. 3. Generic designation for compounds closely related in structure to the steroids, such as sterols, bile acids, cardiac glycosides, androgens, estrogens, corticosteroids, and precursors of the D vitamins.
- anabolic s. a s. compound with the capacity to increase muscle mass; compounds with androgenic properties which increase muscle mass and are used in the treatment of emaciation. Sometimes used by athletes in an effort to increase muscle size, strength, and endurance. Examples include methyltestosterone, nandrolone, methandrostenolone, and stanozolol.
- s. 21-monooxygenase an enzyme catalyzing the reaction of a s., O2, and some reduced compound to produce water, the oxidized compound, and a 21-hydroxysteroid; a deficiency of this enzyme results in decreased cortisol synthesis, of which there are three types (salt-wasting, simple virilizing, and nonclassical).
- s. monooxygenases enzymes catalyzing addition of hydroxyl groups to the s. rings utilizing O2; differentiated into, for example, s. 11β-monooxygenase, s. 17α-monooxygenase, and s. 21-monooxygenase, in accordance with the position of the catalytically introduced hydroxyl group. SYN: s. hydroxylases.
- s. 5α-reductase an enzyme that uses NADPH to reduce certain steroids ( e.g., the conversion of testosterone to dihydrotestosterone); a deficiency of this enzyme is associated with a form of male pseudohermaphroditism in which genetic males have male genitals as well as female external genitalia.
- s. sulfatase deficiency SYN: X-linked ichthyosis.

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ste·roid 'sti(ə)r-.ȯidalso 'ste(ə)r- n any of numerous natural or synthetic compounds containing a 17-carbon 4-ring system and including the sterols and various hormones and glycosides see anabolic steroid
steroid or ste·roi·dal stə-'rȯid-əl adj

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n.
one of a group of compounds having a common structure based on the steroid nucleus, which consists of three six-membered carbon rings and one five-membered carbon ring. The naturally occurring steroids include the male and female sex hormones (androgen and oestrogen), the hormones of the adrenal cortex (see corticosteroid), progesterone, bile salts, and sterol. Synthetic steroids have been produced for therapeutic purposes.

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ster·oid (sterґoid) any of a group of lipids that contain a hydrogenated cyclopentanoperhydrophenanthrene ring system. Substances included in this group include progesterone, adrenocortical hormones, sex hormones, cardiac aglycones, bile acids, sterols (such as cholesterol), saponins, toad poisons, and some carcinogenic hydrocarbons.

Medical dictionary. 2011.