Cortisol production, regulation and function. Causes of Cushing syndrome, Cushing disease; pathophysiology, signs and symptoms, diagnosis and treatment. Category: endocrine and metabolic disorders. This video is available for instant download licensing here: https://www.alilamedicalmedia.com/-/g...
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Cushing syndrome is a group of conditions caused by high levels of circulating cortisol or related corticosteroids.
Cortisol is a steroid hormone produced by the adrenal gland. Cortisol production is stimulated by the pituitary hormone ACTH. The secretion of ACTH is, in turn, promoted by the hypothalamic hormone CRH.
Cortisol helps the body deal with stress by mobilizing energy resources. It increases blood glucose level and makes glucose more available to the brain, as compared to other organs. For example, cortisol induces muscle cells to decrease glucose consumption and increase protein degradation, producing amino acids that can be converted into new glucose, a process known as gluconeogenesis. Cortisol also helps maintain high blood pressure to keep the body stay on high alert.
On the other hand, high levels of corticosteroids suppress inflammation and antibody production by B-cells. For this reason, cortisol and related products such as prednisone are used to treat inflammatory conditions and autoimmune diseases. These medications also help suppress the immune system to prevent organ rejection in transplant recipients.
Cushing syndrome usually results from excessive use of corticosteroid drugs, or overproduction of cortisol by the adrenal glands. A tumor in the adrenal gland may produce excess cortisol regardless of ACTH levels. On the other hand, the adrenal glands may be normal, but they are overstimulated by high ACTH levels produced by a tumor in the pituitary gland or another organ. This group of conditions is more specifically known as Cushing disease.
Corticosteroids cause obesity and alter the body fat distribution. Excessive fat develops specifically in the face and torso. Patients commonly have a round face, a hump on the back, and disproportionately slender arms and legs. Other signs include muscle wasting, thin and easily bruised skin, and purple streaks over the abdomen or chest. In the long term, patients may develop high blood pressure, diabetes, weakened bones, and vulnerability to infections.
There are several diagnostic tests for cortisol levels. Because normal cortisol secretion follows a daily rhythm - high in the morning and low at night, a high midnight cortisol level is an indicator of the disease.
ACTH levels are measured to determine the cause. Low ACTH levels suggest a primary adrenal cause, while high levels are indicative of a pituitary cause or an ectopic ACTH source.
Imaging tests can be used to detect tumors.
Supportive treatment includes diets high in proteins and potassium. If corticosteroid drugs are the cause, they may be gradually reduced to optimal levels. Certain medications can be used to block cortisol production, or block the effects of cortisol. Tumors are usually removed surgically or treated with radiation therapy.