Cushing's syndrome

Introduction Cushing's syndrome is also known as hvpercortisolism or Cushing's syndrome. In 1912, it was first reported by Harvey Cushing. Intrinsic is a clinical syndrome characterized by hypercortisolemia caused by multiple causes, mainly characterized by full moon face, multiple blood appearance, central obesity, hemorrhoids, purple lines, high blood pressure, secondary diabetes and Osteoporosis and so on. Cushing's syndrome is mainly caused by a series of clinical symptoms and signs caused by excessive secretion of cortisol from the adrenal cortex, but it also secretes other hormones. Therefore, the syndrome is multi-variant and belongs to the mixed type of cortisol.

Cause

Cushing syndrome is common in the hypothalamic-pituitary lesions in the clinic, and is generally classified according to the cause.

Cortisol can be divided into the following four types according to its etiology and pathological changes of pituitary and adrenal glands:

Iatrogenic cortisol

Long-term use of glucocorticoids in the treatment of certain diseases can lead to clinical manifestations of cortisol, which is very common in the clinic. This is caused by exogenous hormones and can be gradually restored after stopping the drug. However, long-term use of glucocorticoids can feedback the secretion of ACTH in the pituitary gland, causing atrophy of the adrenal cortex. Once the drug is stopped, it may lead to a series of manifestations of cortical dysfunction and even crisis, so it should be noted. Cortisol can also occur with long-term use of ACTH.

2. Pituitary bilateral adrenal hyperplasia

Bilateral adrenal hyperplasia is caused by excessive secretion of ACTH from the pituitary gland. The reason: 1 pituitary tumor. More common basophils, also seen in chromoblastoma; 2 pituitary no obvious tumor, but increased secretion of ACTH. It is generally believed to be caused by excessive secretion of corticotropin releasing factor (CRF) from the hypothalamus. Clinically, only about 10% of the pituitary tumors can be found. In this type of case, due to the abnormal high level of ACTH secretion from the pituitary, the increase of plasma cortisol is not enough to cause normal feedback inhibition, but oral high-dose dexamethasone can still inhibit.

3. Bilateral adrenal hyperplasia caused by extracorporeal lesions

Bronchial lung cancer (especially oat cell carcinoma), thyroid cancer, thymic carcinoma, nasopharyngeal carcinoma, and tumors originating from neural crest tissue sometimes secrete an ACTH-like substance with a biological effect similar to ACTH, causing bilateral adrenal cortex Hyperplasia, so called heterologous ACTH syndrome. These patients also often have significant muscle atrophy and hypokalemia. The secretion of ACTH substances in the lesions is autonomous, and oral high-dose dexamethasone has no inhibitory effect. After the lesion is removed or cured, the condition gradually subsides.

4. Adrenal cortical tumor

Most are benign adrenal adenomas, and a few are malignant adenocarcinomas. Tumor growth and secretion of adrenocortical hormone are autonomous and not controlled by ACTH. Since the tumor secretes a large amount of corticosteroids, the feedback inhibits the secretion function of the pituitary, which lowers the plasma ACTH concentration, so that the normal adrenal cortex of the non-tumor part is obviously atrophied. In patients with this type of ACTH-induced or high-dose dexamethasone, the amount of cortisol secreted does not change. In adrenal cortical tumors, especially malignant tumors, 17 ketosteroids in urine are often significantly increased.

an examination

X-ray inspection

(1) Sella or flat-slice method Because the pituitary tumors of patients with Cushing's disease are small, the results of the plain film method are mostly negative, and some patients have only mild abnormal changes with the serrano layered method, and Poor sensitivity and low accuracy. However, if the saddle is found to increase, it is helpful for the diagnosis of pituitary tumors.

(2) Adrenal X-ray method is helpful for the location of adrenal space-occupying lesions, but can not identify nodular hyperplasia and adenoma.

2. CT examination

Since the CT scan is about 10 mm per layer, CT resolution is good for pituitary adenomas >10 mm in diameter, but for pituitary microadenomas less than 10 mm in diameter, CT may be missed, with a positive rate of 60%. So CT. No pituitary tumors were found, and the possibility of microadenomas could not be ruled out.

For the examination of adrenal hyperplasia and adenoma, CT has a large effect and good resolution, because the diameter of adrenal adenoma is often >2cm.

Note: CT examination, to inject contrast agent, in order to prevent allergic reaction, generally give 10mg dexamethasone; CT examination should be arranged after a large dose of dexamethasone inhibition test, otherwise it should be more than 7 days and then do a large dose of ground The dexamethasone suppression test.

3. Magnetic resonance (MRI) examination

For Cushing's disease, MRI is the preferred method. Compared with CT, the hypothalamic pituitary and parasagittal structures (cavernous sinus, pituitary stalk and optic chiasm) can be well distinguished, but for tumors <5mm in diameter, the resolution is still only 50%.

4.B Ultra

It is good for adrenal hyperplasia and adenoma, and it is non-invasive, convenient, cheap and accurate. It is often used together with MRI and CT for the localization diagnosis of Cushing's syndrome.

5. Other

(1) 131I--iodinated cholesterol adrenal scanning can show the location and function of adrenal adenoma, the adenoma side is concentrated, the contralateral side is often not developed, the image is not as clear as CT.

(2) Under the sinus ACTH measurement (IPSS) Selective vein blood was taken and ACTH was measured. If the patient has a biochemical test for Cushing's disease and the CT scan is negative, this test can be performed.

Differential diagnosis

1. Simple obesity and type 2 diabetes: may have obesity, hypertension, abnormal glucose metabolism, menstrual disorders, skin white lines, etc., blood cortisol and its metabolites are increased, but can be inhibited by low-dose dexamethasone, cortex Alcohol and ACTH rhythm are normal.

Second, pseudo Cushing syndrome: alcoholic liver damage, not only various symptoms and hormone levels similar to this disease, and no response to small doses of dexamethasone or reduced response, but abstinence can be restored.

Third, depression: Although the increased hormone and its metabolites are not inhibited by small doses of dexamethasone, but no clinical manifestations of Chushing syndrome.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.