American Medical Association Family Medical Guide - American Medical Association [613]
The adrenal cortex produces three different groups of corticosteroid hormones. The hormones in the first group regulate the concentration and balance of various chemicals in the body. The most important hormone in this group is aldosterone, which helps control blood pressure and regulates sodium and potassium levels in the body. The hormones in the second group have a number of functions, including helping to convert carbohydrates into energy-rich glycogen in the liver. (Glycogen has an essential role in regulating blood sugar levels.) Cortisol is the main hormone in this group.
The third group of hormones consists of androgens (male sex hormones) and estrogen and progesterone (female sex hormones), which regulate sexual development and the functioning of the reproductive system. Sex hormones are produced mainly by the testicles and the ovaries. Although both sexes produce male and female sex hormones, androgens are more prevalent in men and estrogen and progesterone are more prevalent in women.
The pituitary gland controls the production of most corticosteroid hormones. The only exception is aldosterone, which is stimulated by the hormone renin, produced by the kidneys.
Cushing’s Syndrome
Cushing’s syndrome is a rare condition that results from an excess of corticosteroid hormones in the blood. The disorder usually results from taking large doses of corticosteroid drugs for long-term treatment of an inflammatory illness such as rheumatoid arthritis (see page 918) or asthma (see page 640). In rare cases, the condition develops when the outer layer of one or both adrenal glands (the adrenal cortex) produces excessive amounts of corticosteroid hormones. Overproduction of corticosteroid hormones can occur when a tumor in one of the adrenal glands or elsewhere in the body over-stimulates the adrenal glands. If the tumor that is causing the excess hormone production is in the pituitary gland in the brain, the condition is called Cushing’s disease rather than Cushing’s syndrome. Cushing’s syndrome is most common in young to middle-aged women.
Symptoms
The symptoms of Cushing’s syndrome usually appear gradually, over a period of several months. First, the face becomes large and round. Excess fat forms on the body, and a pad of fat develops between the shoulder blades. At the same time, muscles in the arms and legs lose mass and weaken. The skin may become thinner and may bruise easily. Over time, blood pressure increases and the bones become thin and fracture easily (osteoporosis; see page 989).
Diagnosis
A diagnosis of Cushing’s syndrome is based on the symptoms and a physical examination. The doctor will recommend blood and urine tests to measure the levels of cortisol, the major corticosteroid hormone. If cortisol levels are high, the doctor may recommend a 24-hour urine test to evaluate pituitary function and determine if there is a tumor in the pituitary gland. For a 24-hour urine test, you collect a sample of urine each time you urinate over a 24-hour period. Depending on the test results, the doctor may also recommend a CT scan (see page 112) or an MRI (see page 113) to look for a tumor in the pituitary or in the adrenal glands. If no tumor is detected, he or she may recommend an X-ray or CT scan of the lungs to check for lung cancer (some tumors in the lungs secrete corticosteroidlike hormones).
Treatment
If long-term corticosteroid treatment for another disorder is the cause of Cushing’s syndrome, your doctor will either adjust the dosage of the medication you are taking or prescribe a different drug. If the disorder results from a pituitary tumor, the doctor may recommend surgery or radiation therapy to remove or destroy the tumor. If you have a tumor in one adrenal gland, the doctor will recommend surgery to remove the gland; your body should function normally with the remaining adrenal gland. In some cases, both adrenal glands are removed surgically. If both adrenal glands are removed, you will need to take corticosteroid drugs for the rest of your life to replace the