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What are hormones?
- A hormone is a substance that exerts a physiological control over other cells in the body. Hormones are secreted into the body by a gland and usually exert their effect at a distant location.
- Hormones are the primary message transmitters of' the endocrine system.
- The mechanism that controls the release hormones.
- thyroid-releasing factor stimulates the release of thyroid stimulating hormone that in turn causes the thyroid gland to release its hormone, thyroxine.
- When the level of thyroxine in the blood rises above normal, the secretion of thyroid releasing factor is inhibited.
produces the hormones thyroxine (T4), triiodothyronine (T3) and several other thyroid hormones. T3 is about four times as potent as T4, but much shorter acting.
Effects of Thyroid Hormones
- Increased metabolic rate: Increased protein synthesis, Increased enzyme activity, Increased activity of mitochondria
- Changes in metabolism of dietary substances: Increased bone growth, Increased carbohydrate metabolism, Increased fat metabolism
- Changes in body mechanisms:
- Decreased body weight
- Increased heart rate
- Increased force of contraction in the heart
- Increased blood volume
- Increased blood pressure
- Increased respiration
- Increased GI motility
- Increased gastric secretions
- Increased CNS activity, nervousness
- Causes: Tumors, Autoimmune diseases (Grave�s Disease)
- Symptoms: Nervousness, Diarrhea, Increased heart rate, Fatigue, but inability to sleep, Increased sweating, Weight loss, Intolerance to heat
- Destroy part of thyroid gland with radioactive iodine
- Surgical removal of part of thyroid gland
- Drugs: Propylthiouracil (PTU), Potassium iodide and iodine (Lugol�s Solution), Thyroid Storm
- Causes: Gland destruction, Lack of iodine, Pituitary dysfunction, Surgical removal of gland
- Symptoms: Goiter, Extreme somnolence, Slow heart rate, Decreased cardiac output, Weight gain, Constipation, High cholesterol
- Thyroid USP - T3 & T4
- Levothyroxine Sodium - T4 (Synthroid, Levoxyl, Levothroid, Unothroid)
- Liothyronine Sodium - T3 (Cytomel)
- Liotrix - T3 & T4 (Euthroid, Thyrolar)
- Take thyroid replacement at the same time each day
- Do not change brands without checking with physician
- Blocks the synthesis of T3 and T4 and the conversion of T4 to T3.
- Palliative treatment of hyperthyroidism to return the hyperthyroid patient to a normal metabolic state before a thyroidectomy and to control thyrotoxic crisis.
Life threatening medical emergency
- The adrenal glands are located on top of the kidneys.
- They are composed of two parts, the medulla and the cortex.
- The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine in response to sympathetic stimulation.
- The cortex secretes corticosteroids, composed of glucocorticoids and mineralocorticoids.
- Increased secretion of corticosteroids
- weight gain, excess growth of facial hair, CNS changes and high blood pressure.
- Decreased secretion of corticosteroids
- dehydration, hypotension and muscle weakness
include cortisol and cortisone
Effects of Cortisol
- Stimulation of gluconeogenesis (breakdown of amino acids into glucose)
- Decrease cellular use of glucose
- Increased blood glucose
- Mobilization of fatty acids from adipose tissue
- Antiinflammatory effects (mechanism unknown)
- Increase in circulating white blood cells
- Methylprednisolone (Medrol, Solu-Medrol, Depo-Medrol)
- Prednisone (Deltasone)
doses of glucocorticoids should be reduced gradually, not abruptly, in order to give the adrenal glands time to start normal production.
- Promotes development and maintenance of male physical characteristics.
- Also produced by the ovaries in females
- The most important male hormone is testosterone, which is produced by the testes.
- Replacement therapy (pituitary disorders, testicular failure, castration)
- Anabolic action
- Breast cancer
- Develop uterine lining (endometrium) and mammary glands for pregnancy
- Cause development of secondary sex characteristics in the female
- Effects of Abnormally High Levels of Estrogen: Inhibits LH surge which prevents ovulation, Mechanism of action for oral contraceptives
- Conjugated Estrogens (Premarin)
- secreted mainly in the second half of the ovarian cycle.
- During pregnancy, ten times the normal amount of progesterone is secreted by the placenta.
- Progesterone promotes changes in the uterus to prepare for implantation of the fetus.
- Medroxyprogesterone (Provera)
How do oral contraceptives work?
- sufficient quantities of progestins and estrogens can inhibit the LH surges, thus inhibiting ovulation.
- used to prevent conception, to give enough of the hormones to prevent ovulation, but not enough to cause unwanted side effects.
Selective Estrogen Receptor Modulators (SERM�s)
- SERM�s compete with estrogen for binding sites in target tissues such as the breast and uterus.
- Tamoxifen (Nolvadex): Useful in adjuvant therapy and treatment of breast cancer, Recently approved for preventative therapy in women at high risk for primary breast cancer
- Raloxifene (Evista): Produces estrogen-like effects on bone and lipid metabolism, Does not stimulate breast or uterine tissue, Approved for prevention of osteoporosis, Not useful for hot flashes
- used to treat Padget�s Disease and hypercalcemia.
- used to prevent and treat osteoperosis
- Bisphosphonates are not hormones.
- Take at least 30 minutes before the first food, drink or medication of the day
- Take with a full glass of water (at least 6 to 8 ounces)
- Avoid lying down for at least 30 minutes after drug administration
- Oral: Alendronate (Fosamax),Risedronate (Actonel), Ibandronate (Boniva)
- Injectable: Pamidronate (Aredia)
Agents for osteoporosis
- Raloxifene (Evista)
- Alendronate (Fosamax)
- Risedronate (Actonel)
- Ibandronate (Boniva)