| History: Frequent complaints include weight gain, fatigue, muscle weakness (especially of the upper arms and thighs), easy bruising, poor wound healing, thinning scalp hair, abnormal growth of body hair and purple streaking (striae) of the breasts, buttocks, lower abdomen and thighs. Individuals may also complain of excessive thirst and frequent urination. Psychiatric symptoms include mood swings, depression, and personality changes (steroid psychosis). Women may notice changes in the menstrual flow (oligomenorrhea or amenorrhea), and men may complain of decreased sex drive (libido) and inability to achieve or maintain an erection (erectile dysfunction). Often, individuals will report that routine bending, lifting, or rising from a chair has become difficult or painful. Physical exam: High blood pressure (hypertension) is seen in over 80% of cases. There are some striking physical changes in Cushing's syndrome. The face is round and unusually red. Acne may be present. Obesity is common; 50% of individuals gain weight in the abdomen and buttocks while the arms and legs are normal. Fat pads appear over the collarbones and upper spine. Tests: If it has been determined from the history and physical exam that the individual is not showing the signs of Cushing's syndrome from prescribed medications, further testing is carried out at two levels. First, it must be determined whether the individual has elevated levels of cortisol. A 24-hour urine collection is taken, and the amount of cortisol in the urine is measured. The cortisol level will be elevated in individuals with Cushing's syndrome. Another test is the overnight dexamethasone suppression test. Dexamethasone is a steroid medication that suppresses ACTH release and lowers the early morning levels of blood cortisol in normal individuals but has no effect in individuals with Cushing's syndrome. A newer means to detect Cushing's syndrome uses a combination of the CRH stimulation test with the dexamethasone suppression test. Cortisol levels exceeding 1.4 µg per L would be diagnostic for Cushing's syndrome. This method is reported to have a very high rate of diagnostic accuracy.
Once the diagnosis of Cushing's syndrome is established, a second level of testing is carried out to determine the cause of the disease: a tumor of the pituitary gland or adrenal glands or a tumor that stimulates the adrenal glands through ectopic ACTH secretion. A test called the CRH stimulation test is often performed to help distinguish individuals with Cushing's syndrome due to pituitary adenomas from those with ectopic ACTH syndrome or cortisol-secreting adrenal tumors. In the CRH stimulation test, individuals are given an injection of CRH. Those with a pituitary adenoma usually experience a rise in blood levels of ACTH and cortisol. This response is rarely seen in people with ectopic ACTH syndrome and practically never in those with cortisol-secreting adrenal tumors.
Routine chest x-rays are done, along with CT of the chest in suspected cases of ectopic ACTH production. A CT of the adrenal glands can show an adrenal tumor, or in the case of a pituitary tumor that stimulates both glands, enlarged adrenal glands. MRI of the pituitary gland is done in cases of suspected pituitary tumors. Pituitary adenomas are only seen on 50% of MRI tests, so it is important that the biochemical testing is thorough before surgery (Kirk).
Blood tests may also show high levels of sugar (hyperglycemia), fat (hyperlipidemia), or potassium (hyperkalemia) and abnormal numbers of certain white blood cells (neutrophilia, lymphopenia). |
Source: Medical Disability Advisor