Cushing's disease is a condition in which the body secretes or is exposed to too much cortisol, a steroid hormone important in stressful situations. Cortisol also has some effects on the body's handling of potassium, an electrolyte important in the process of muscle movement, transmission of signals in the nervous system, fluid balance in the body and the heart's rhythm.
Facts about Cushing’s Disease
According to the Merck Manuals, Cushing's disease results from abnormal secretion of the hormone ACTH from the pituitary gland in the brain. ACTH stimulates the adrenals, triangular-shaped glands that sit atop the kidneys, to secrete cortisol. Too much ACTH results in too much cortisol secreted by the adrenals. Other sources of excess ACTH include increased secretion of the hormone by lung tumors or from other sources. Cushing's syndrome also results from prolonged ingestion or exposure to steroid medications and drugs.
Facts about Potassium
Potassium works to stimulate muscle contraction and to relay the electrical signal in the heart to maintain an appropriate heart rhythm. Most potassium is contained inside the body's cells, so small changes in the level of potassium in the bloodstream can have serious health consequences. Good dietary sources of potassium include bananas, citrus fruits like oranges and lemons, beans, tomatoes and certain fishes, like salmon and cod.
Effects of Cushing’s Disease on Potassium Level
The elevation of cortisol level in people with Cushing's disease causes a decrease in the level of potassium, a condition called hypokalemia. At high levels, cortisol stimulates the tubules that control the absorption of electrolytes in the kidneys to excrete more potassium into the urine. According to the National Adrenal Diseases Foundation, this happens more often in people who have Cushing's disease because of increased production of ACTH in other places than the pituitary, like a lung tumor.
Symptoms of Cushing’s Disease
According to the Mayo Clinic, the symptoms of Cushing's disease vary from patient to patient. In general, symptoms include weight gain with deposition of fat in the mid-body, upper back between the shoulder blades, giving the appearance of a hump, and on the face. Skin changes occur and include easy bruising, stretch marks and acne. Women can develop thicker facial and body hair, while men can have decreased fertility and libido. Other symptoms include muscle weakness and fatigue and changing mental status with easy irritability and poorly controlled emotions.
Symptoms of Low Potassium
Low potassium, or hypokalemia, can also cause muscle weakness, with cramps and twitches, low blood pressure and decreased breathing. Patients can also have paralysis and rhabdomyolisis, or muscle cell breakdown. As the level of potassium decreased, the chances of abnormal heart rhythms increase. These can be as mild as skipped beats or as serious as ventricular fibrillation, an abnormal rhythm that can be fatal.