Midnight one tablet of dexamethasone suppression test

A midnight dexamethasone suppression test was carried out by the following principle. Under normal conditions, pituitary secretion of ACTH is regulated by cortisol levels in the blood circulation. Exogenous administration has a strong inhibitory effect on pituitary ACTH secretion, but its own dose is very small. It has little effect on blood and urinary cortisol determination of synthetic corticosteroid-dexamethasone, and changes in blood and urinary cortisol and plasma ACTH. It can reflect the function of the pituitary secretion of ACTH and whether the adrenal function is dependent on ACTH. Cushing disease can be distinguished from Cushing syndrome. Basic Information Specialist classification: growth and development examination classification: blood examination Applicable gender: whether men and women apply fasting: not fasting Tips: Should be careful not to bring non-urine ingredients into the urine. For example, female patients should not mix vaginal discharge and menstrual blood. Normal value Serum cortisol decreased by more than 50% after taking a dexamethasone normal and simple obesity. Serum cortisol was reduced to 112.7 nmol/L in this patient. The patient's inhibition values ​​were similar to those of normal people. Clinical significance Small dose method: (1) After 24 hours after taking the drug, UFC decreased to below 69.0 nmol, blood ACTH decreased to below 4.4 pmol/L, and serum cortisol decreased to below 82.8 nmol/L. (2) After obesity, the UFC decreased to less than 110.4 nmol after 24 h, the plasma ACTH decreased to less than 5.5 pmol/L, and the serum cortisol decreased to below 138.0 nmol/L. (3) There was no significant decrease in UFC, plasma ACTH and serum cortisol after 24 hours of Cushing disease (or syndrome) or ectopic ACTH secretion. The values ​​after inhibition were greater than those of simple obesity, but very few Cushing The inhibition values ​​of patients with symptoms are similar to those of normal people and simple obesity. Abnormal results Cushing disease (or syndrome) or ectopic ACTH secretion of significant pigmentation, hypertension, edema, severe hypokalemia with muscle weakness. Diabetes with polydipsia, drink more urine. Weight loss. Plasma ACTH and cortisol increased significantly, mainly lung, pancreas, intestinal carcinoid, and pheochromocytoma; these tumors have a longer course. The condition is mild. And the carcinoid volume is often small. Therefore, clinically it can be expressed as a typical Cushing syndrome. The population to be examined are: Cushing disease (or syndrome) or suspected symptomatic patients with ectopic ACTH syndrome. Precautions Care should be taken not to bring non-urine ingredients into the urine: such as female patients do not mix vaginal discharge and menstrual blood, male patients should not mix with prostatic fluid. Check the urine volume: generally 5 ~ 10ml, if you want to measure the specific gravity of the urine can not be less than 50ml. Inspection process There are three common methods used in clinical practice: 1. Overnight dexamethasone suppression test: 1 mg of dexamethasone orally before bedtime (about 12:00 pm), fasted until 8:00 am the next day, and blood plasma cortisol was measured. In normal people and obese people, plasma cortisol can be inhibited to less than 50 μg / L, and hypercortisolism is not inhibited. 2, low-dose dexamethasone inhibition test: 17 hours before the test, urine 17-hydroxysteroids, dexamethasone 0.5mg, or 0.75mg every 6h, every 8h, every day for 24h urine test 17 - Hydroxy steroids. In normal people or obese people, 17-hydroxysteroid discharge is significantly reduced, which can be reduced to less than 2.5 mg or less than 50% of the control value, while patients with hypercortisolism are not inhibited. 3, high-dose dexamethasone inhibition test: the method is the same as the small dose, but the dosage of dexamethasone is changed to 2mg of oral dexamethasone every 6h, and 16mg is used for 2d. Cortisol is caused by adrenal hyperplasia, and the urinary 17-hydroxysteroid discharge can be reduced by more than 50%, but the tumor is not inhibited (including cortical adenoma, adenocarcinoma, and ectopic ACTH syndrome). Not suitable for the crowd There are no special taboos. Adverse reactions and risks No obvious complications and harms.

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