Endocrine Medications 2: Sex Hormones

The HPG axis is a complex system of hormones and glands that regulate the reproductive system. It involves the hypothalamus, pituitary gland, and gonads (testes in males and ovaries in females).

GnRH is released by the hypothalamus and stimulates the pituitary gland to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

FSH, produced by the pituitary gland, stimulates the development of follicles (eggs) in females and sperm production in males.

LH, also produced by the pituitary gland, plays a crucial role in ovulation in females and testosterone production in males.

Estrogen is a female sex hormone produced primarily by the ovaries. It plays a vital role in development of female secondary sex characteristics, menstrual cycle regulation, and bone health.

Progesterone is another female sex hormone produced primarily by the ovaries. It prepares the uterus for pregnancy, promotes breast development, and plays a crucial role in the menstrual cycle.

Testosterone is the primary male sex hormone produced primarily by the testes. It plays a vital role in development of male secondary sex characteristics, sperm production, and muscle mass.

Ovulation is the process where a mature egg is released from the ovary and travels down the fallopian tube, making it available for fertilization.

Mifepristone is a progesterone receptor antagonist used to induce first-trimester abortion. It often is administered with misoprostol, a prostaglandin analogue, which stimulates uterine contractions.

Hormones produced by the adrenal cortex in both sexes, playing a role in various physiological functions.

Excess androgen secretion in women can lead to masculinizing effects.

Oral contraceptives prevent ovulation by inhibiting the release of an egg. They also increase the viscosity of cervical mucous to hinder sperm motility and impede the movement of the ova through the fallopian tubes.

Anti-estrogens work by blocking the negative feedback of estrogens in the hypothalamus, which leads to an increased release of LH and FSH, stimulating ovulation.

Gonadotropin therapy is used in women who lack pituitary function or do not respond to Clomifene therapy. It involves administering menotropin or urofollitropin followed by chorionic gonadotropin to induce ovulation.

In men with hypogonadotrophic hypogonadism, both LH and FSH are given to stimulate spermatogenesis (sperm production) and androgen release to improve testosterone levels.

Androgen deficiency is treated with intramuscular injections of testosterone propionate.

Clomid, a medication, stimulates FSH and LH production, which promotes follicle maturation, ovulation, and corpus luteum development. It's utilized to address inadequate ovulation in females and low sperm count in males.

Pitocin (oxytocin) acts as a powerful uterine muscle stimulant, enhancing contractions. It's used to treat postpartum hemorrhage, ensuring the uterus contracts and stops bleeding.

Yutopar (ritodrine) blocks specific receptors in the uterus, preventing contractions and delaying premature labor. It's used when the gestation period is longer than 20 weeks.

Testosterone, a male hormone, is used for various conditions including low sperm count, impotence, and undescended testicles. It has anabolic effects, aiding in osteoporosis, anemia, and general weakness. However, it carries risks like edema, acne, and increased LDL cholesterol levels.

Despite multiple trials, male contraceptives face challenges. Only around 60% of men achieve azoospermia (no sperm) and side effects like acne, weight gain, and potential prostate enlargement remain concerns.

Large doses of testosterone in adult males lead to a decrease in gonadotropin release, resulting in shrinking of testicular tissue and tubules.

Androgens, including testosterone, in females can cause changes similar to those seen in prepubertal males.

The primary estrogen produced by the ovaries is responsible for the development and maintenance of female reproductive characteristics.

Synthetic estrogens are often more effective when administered orally compared to naturally occurring estrogens.

Progestogens are used in hormonal contraceptives to suppress ovulation and alter cervical mucus, making it difficult for sperm to reach the egg.

Combination oral contraceptive pills work by inhibiting the release of GnRH, leading to a decrease in gonadotropin secretion. This creates an unfavorable environment for implantation and alters cervical mucus.

Progestogen-only pills primarily affect cervical mucus and ovaduct motility, hindering sperm transport and egg fertilization. They are less effective in blocking ovulation compared to combination pills.

Absolute contraindications for oral contraceptives include thromboplebitis, stroke, breast cancer, pregnancy, liver disease, coronary artery disease, and smoking in individuals older than 35.

Combined oral contraceptives (COCs) are the most potent and effective method for suppressing the secretion of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH).

Combined oral contraceptives (COCs) typically contain a combination of estrogen (ethinyl estradiol or mestranol) and a progestin.

Progestins in COCs act as potent progesterone receptor agonists, but they can also have some androgenic cross-reactivity. This means they can influence certain male sex hormone-related processes.

COCs are available in three different delivery systems: oral tablets, vaginal rings (containing ethinyl estradiol and etonogestrel), and transdermal patches (containing ethinyl estradiol and norelgestromin).

Breakthrough bleeding and irregular menses are common non-life-threatening side effects experienced by women taking COCs.

Serious adverse effects of COCs include cholestatic jaundice (liver dysfunction), thromboembolic disease (blood clots), and thromboembolism (blood clots in the lungs or legs).

Emergency contraception, usually containing levonorgestrel, works by preventing ovulation by blocking the LH surge. It is most effective when taken within 3 days of unprotected intercourse.

Mifepristone, a progesterone antagonist, is highly effective in terminating early pregnancy (up to 63 days gestation) when used with a prostaglandin (PG) cervical ripening agent. It works by blocking the action of progesterone, which is essential for maintaining the pregnancy.