How long to diagnose cushings

If blood tests show that the tumor is ectopic, imaging tests can help locate the tumor. The most common imaging tests are the computerized tomography CT scan and magnetic resonance imaging MRI. Petrosal sinus sampling. Pituitary tumors are usually small and may not show up in an imaging test.

This test is often the best way to tell pituitary from ectopic causes of Cushing's syndrome. Your doctor will draw samples of blood from your petrosal sinuses—veins that drain the pituitary. At the same time, you will have a blood sample taken from a blood vessel far away from the pituitary. Higher levels of ACTH in the blood from the petrosal sinuses than from the other blood vessel indicate a pituitary tumor. Similar levels of ACTH in all the blood samples suggest an ectopic tumor.

Treatment depends on the cause and may include surgery, radiation, chemotherapy, or cortisol-reducing medicines. If the cause is long-term use of glucocorticoids to treat another disorder, your doctor will gradually reduce your dosage to the lowest dose that will control that disorder.

Sometimes disorders that doctors treat with glucocorticoids can be treated with a non-glucocorticoid medicine instead. The most common treatment for pituitary tumors is surgery to remove the tumor. Using a special microscope and fine instruments, a surgeon approaches the pituitary gland through a nostril or an opening made below the upper lip. Your doctor will probably refer you to a center specializing in this type of surgery.

The success, or cure, rate of this surgery can be as high as 90 percent when done by a highly experienced surgeon. You may be able to stop cortisol medicine in 6 to 18 months.

One type of radiation therapy uses small doses of radiation to the pituitary over a 6-week period. Another type uses a single, high dose of radiation. Cortisol levels may not return to normal after radiation therapy for several years.

Your doctor may prescribe medicines to bring cortisol levels back to normal until radiation therapy takes effect. The first choice of treatment for ectopic tumors is to remove them surgically. If the tumor is cancerous and has spread, you may need chemotherapy, radiation therapy, or other cancer treatments. Medicines to reduce cortisol levels may also be part of your treatment.

Surgery to remove the adrenal gland with the tumor is the most common treatment. The clinical diagnosis must be based on the presence of one or more of these findings Figure 1 , because the syndrome itself has no true pathognomonic signs or symptoms.

The most common symptom is sudden weight gain. Any sign or symptom of cortisol excess can develop initially, but muscle weakness, bruising, hypertension, facial rounding and plethora eventually occur. Hypertension is likely to develop in patients who are more than 40 years of age. Pituitary tumors are known to compress the optic chiasm.

Bitemporal hemianopsia with central visual field defects is the classic neuro-ophthalmologic finding, although other visual defects, including unilateral symptoms, can occur. Cranial nerve III oculomotor nerve palsies are less well recognized, but they may occur in up to 25 percent of patients with pituitary macroadenomas and may be the lone presenting symptom in patients with pituitary adenomas. Another presentation or complication of Cushing's disease is opportunistic or bacterial infection.

Immunosuppression resulting from corticosteroid excess is usually thought of as a cellular immune deficiency 11 that increases the risk of opportunistic infections Cryptococcus neoformans , Candida species, Norcardia species and other organisms.

Recent studies have also demonstrated the effect of glucocorticoids on the humoral immune system. In the first description of the disease, 15 eight of the 12 cases were complicated by bacterial infections. Subsequent case reports have further emphasized the frequency of bacterial infections in Cushing's disease.

When stimulated by ACTH, the adrenal gland secretes cortisol and other steroid hormones. ACTH is produced by the pituitary gland and released into the petrosal venous sinuses in response to stimulation by corticotropin-releasing hormone CRH from the hypothalamus Figure 2.

ACTH is released in a diurnal pattern that is independent of circulating cortisol levels: peak release occurs just before awakening, and ACTH levels then decline throughout the day. Neuronal input at the hypothalamic level can also stimulate CRH release. Hypothalamic-pituitary-adrenal axis. Although the adenomas of Cushing's disease secrete excessive amounts of ACTH, they generally retain some negative feedback responsiveness to high doses of glucocorticoids. Ectopic sources of ACTH, usually in the form of extracranial neoplasms, are generally not responsive to negative feedback with high doses of glucocorticoids.

However, some overlap exists in the response to negative feedback between pituitary and ectopic sources of excessive ACTH. Adapted with permission from Orth DN. Cushing's syndrome. Dexamethasone, an exogenous glucocorticoid, is used to test for Cushing's syndrome.

This gluococorticoid does not interfere with cortisol assays but induces similar physiologic responses. If the findings of the history and physical examination suggest hypercortisolism and an iatrogenic cause i.

Algorithm for the suggested work-up of patients with suspected Cushing's syndrome. When Cushing's syndrome is suspected, initial laboratory testing is usually directed at confirming excessive glucocorticoid production.

This is best accomplished through analysis of a hour urine collection for urinary free cortisol excretion. Because of the difficulty in obtaining hour urine collections in many outpatients, some physicians use a l-mg overnight dexamethasone suppression test. For this test, the patient takes l mg of dexamethasone orally at 11 p.

The reported sensitivity of this test is 98 percent; the reported specificity is 80 percent. Obesity, chronic illness, chronic alcoholism and depression can cause false-positive results pseudo-Cushing's syndrome on the 1-mg dexamethasone suppression test and mildly elevated free cortisol values on the hour urine collection. If the result of the dexamethasone suppression test is abnormal or the hour urinary free cortisol level is mildly elevated, a confirmatory test for Cushing's syndrome is needed.

The hour urine collection for urinary free cortisol excretion can be used to confirm the result of the l-mg dexamethasone suppression test. Normal findings on both tests provide strong evidence against the presence of Cushing's syndrome. In the past, a low-dose dexamethasone suppression test was often performed to confirm the diagnosis of Cushing's syndrome. For this test, the patient takes 0. A hour urine collection is performed before the dexamethasone administration and again during the last 24 hours of dexamethasone administration.

A newer approach is to combine a CRH stimulation test with a dexamethasone suppression test. The patient takes 0. Blood for a plasma cortisol measurement is drawn 15 minutes after the CRH injection. A plasma cortisol level exceeding 1. Alternatively, if pseudo-Cushing's syndrome is suspected, a midnight serum cortisol level of less than 7.

Another approach to the patient with suspected pseudo-Cushing's syndrome is to treat the underlying process and retest the patient in a few months. If the unsuppressed hour urinary free cortisol test is unequivocally positive, a confirmatory dexamethasone suppression test is usually unnecessary. This can be accomplished through measurement of the late-afternoon ACTH level.

Late-afternoon after 4 p. A rise in the cortisol value of 20 percent or more above basal level or a rise in the ACTH value of at least 50 percent above basal level is considered evidence for an ACTH-dependent lesion. When test results indicate that a patient has an ACTH-independent lesion, abdominal computed tomographic CT scanning or magnetic resonance imaging MRI is indicated to localize the site of the lesion.

In the standard high-dose dexamethasone suppression test, a baseline hour urine sample is collected. Then the patient takes 2 mg of dexamethasone every six hours for two days total of eight doses. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. This content does not have an English version. This content does not have an Arabic version. Diagnosis Taking glucocorticoid medications is the most common cause of Cushing syndrome.

Request an Appointment at Mayo Clinic. Share on: Facebook Twitter. Show references Jameson JL, et al. Cushing's syndrome. In: Endocrinology: Adult and Pediatric. Philadelphia, Pa. Accessed Jan. Ferri FF. Cushing's disease and syndrome. In: Ferri's Clinical Advisor Lab Tests Online. Nieman LK. Causes and pathophysiology of Cushing's syndrome. Epidemiology and clinical manifestations of Cushing's syndrome. American Association of Neurological Surgeons. Nieman LK, et al.

Treatment of Cushing's syndrome: An Endocrine Society clinical practice guideline. Cushing's syndrome and disease. The Pituitary Society. Morrow ES Jr. AllScripts EPSi. Mayo Clinic. Cushing's syndrome in MEN I may be due to a pituitary, ectopic or adrenal tumor.

The following tests can help determine if there are excessive levels of cortisol being produced:. After a definitive diagnosis has been made, the source must then be determined. The first step in distinguishing the underlying cause is the measurement of ACTH. In contrast, patients with an excess of adrenal cortisol will have a subnormal level.

Performing a high-dose dexamethasone suppression test may be helpful in this situation. This test, similar to the low-dose dexamethasone suppression test, involves taking a high dose of dexamethasone 8 mg at 11 p.

In normal patients, the morning level of cortisol will again be very low. Patients with pituitary tumors will also suppress their serum cortisol level, but those with adrenal tumors will maintain a high level of cortisol production. A high level of cortisol points to a non-pituitary source. Despite the tests described above, distinguishing a pituitary from a non-pituitary ACTH-secreting tumor can be diagnostically challenging. The majority of patients with ACTH-secreting tumors have a pituitary lesion that is often very small.

The following tests are recommended:. If the cause is iatrogenic, from long-term use of glucocorticoid hormones to treat another disorder, the physician will gradually reduce the dose of the externally administered steroid to the lowest dose adequate for control of that disorder.