The effects of cimetidine on the oxidative metabolism of estradiol

Article Abstract:

Cimetidine, a histamine receptor antagonis, is widely used to treat peptic stomach ulcer. Cimetidine is also known to cause gynecomastia and sexual dysfunction in some men. This study demonstrates that the administration of cimetidine decreases the 2-hydroxylation of kestradiol and results in an increase in the blood estradiol concentration. This mechanism may account for the signs and symptoms of estrogen excess reported with the long-term use of cimetidine. The oxidative metabolism of estradiol in humans involves a balance between two competing hepatic pathways. 2-Hydroxylation is dominant, and the resulting catechol estrogens possess a low affinity of the estrogen receptor. 2-Hydroxylation, in particular, may act as an anti-estrogen in human breast-cancer cells. The relative flux through these two pathways may be a factor in the genesis of hormone-responsive diseases associated with hypoestrogenic or hyperestrogenic states.

Analysis, Estradiol, Steroids (Drugs), Steroids (Organic compounds), Cimetidine

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Male hypogonadism with gynecomastia caused by late-onset deficiency of testicular 17-ketosteroid reductase

Article Abstract:

Some men with enlarged breasts (gynecomastia) and reduced testicular function (hypogonadism) may have a deficiency of the enzyme 17-ketosteroid reductase. This enzymatic reaction is the final step in the synthesis of testosterone, the major male sex hormone. Blood analysis on three men with gynecomastia and hypogonadism revealed that all had increased levels of androstenedione, a precursor of testosterone, but low levels of testosterone. The men also had low levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Intramuscular injections of gonadotropin increased their blood levels of androstenedione, but not their blood levels of testosterone. Most individuals with 17-ketosteroid deficiency appear to be females at birth and are often raised as such. However, these men have a late-onset form of the deficiency. Anti-estrogen drugs and testosterone are possible treatments for this deficiency.

Hypogonadism, Hormones, Sex, Sex hormones

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Estrogen excess associated with novel gain-of-function mutations affecting the aromatase gene

Article Abstract:

A chromosomal abnormality may cause excess estrogen secretion in boys and men, according to a study of a man and his son and an unrelated boy. All had severe breast enlargement, which began before the age of 10. They were all found to have a chromosome abnormality affecting the aromatase gene that caused excessive production of estrogen in fat and skin cells.

Chromosome abnormalities

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