Disorders of adrenocortical dysfunction Flashcards
What are the actions of Cortisol?
Increases plasma glucose levels Increases lipolysis Proteins are catabolized Na+ and H2O retention Anti-inflammatory Increased gastric acid production
Cushing’s syndrome
High levels of the steroid hormone cortisol
Who first discovered Cushing’s?
Harvey Cushing’s in 1932 and he made the link between pituitary gland tumors and signs of excess steroid hormones
Epidemiology of Cushing’s
2/1 000 000
onset 20-40 years
3:1 or 15:1 female: male
Definition of Cushing’s syndrome and Cushing’s disease
Syndrome - Excess cortisol in the blood
Disease - excess cortisol in the blood due to an ACTH secreting pituitary tumor
Clinical features of Cushing’s
High Blood Pressure
Fluid retention
Caused by Salt and water retention
How do you investigate Cushing’s
Screening
Confirmation of the diagnosis
Differentiation of the Cause
Screening and confirmation for Cushing’s
Urinary Free cortisol
Diurnal rhythm
Overnight dexamethasone suppression testing
Overnight low dose dexamethasone suppression test
Cortisol is measured at 8 am
Dexamethasone 1mg is given at 11 am
Cortisol is measured at 8 am the next morning
Cortisol suppression to <50mmol/l is normal
Differential diagnosis
True Cushing's syndrome Pseudo Cushing's syndrome Depression Alcoholism Anorexia Nervosa Obesity Exogenous steroids
Dexamethasone suppression test
Low dose
0.5 mg dexamethasone six-hourly, 48 hrs
Results
Complete suppression in a normal subject
If cortisol detectable then the patient has Cushing’s Syndrome
Differential diagnosis carried on
Cushing’s disease - Pituitary Adenoma
Adrenal Tumour - Benign, Malignant
Ectopic ACTH production - Benign, Malignant
What happens if cortisol is less than 50% in a high dexamethasone test?
Pituitary dependent Cushing’s Disease
If cortisol does not suppress then the patient has ectopic ACTH production or an adrenal tumor
High Dexamethasone Suppression test?
2 mg dexamethasone 6-hourly for 48 hours
Difference between Adrenal tumor and Ectopic ACTH production
Low ACTH
High ACTH
CRH test
0.1 ug/kg of human CRH is given
Blood is assayed for ACTH and cortisol at timed intervals
An exaggerated response indicates pituitary-dependent Cushing’s disease
The flat response indicates ectopic ACTH production
How do you find the tumors?
Pituitary - MRI, IPSS
Adrenal - CT or MRI
Ectopic - Octreotide scan ACTH sampling
What is IPSS?
Inferior petrosal sinus sampling to measure ACTH from the veins from the pituitary gland and the ACTH from peripheral blood.
Octreotide scan
also known as somatostatin receptor scintigraphy, is a test used to check the body for the presence of neuroendocrine tumor cells.
Treatment of Cushing’s
Cortisol production blockers
DXT three field or gamma knife
Adrenal source - remove the tumor source
Steroid replacement tablets
Addison’s clinical Features Part 2
Hyponatraemia
Hyperkalaemia
Acidosis
Hypercalcemia
Addison’s clinical Features Part 1
Hyponatremia Hyperkalaemia Acidosis Hypercalcemia Hypoglycemia Increased urea and creatinine Eosinophilia Lymphocytosis
Causes of Addison’s syndrome part 1
Autoimmune TB Steroid withdrawal Metastases Infiltration Amyloid Hemochromatosis Waterhouse - Freidrichson Apoplexy
Causes of Addison’s syndrome part 2
Infection fungal Viral Enzyme defect Drugs
