Cushing's syndrome

Question 1

Cushing’s syndrome

Answer 1

endocrine disorder with elevated cortisol levels in the blood

Question 2

Cushing’s disease

Answer 2

If excess cortisol results from pituitary adenoma which releases excess ACTH

Question 3

Physiology

Answer 3

1. Hypothalamus secretes corticotropic hormone
2. Pituitary gland stimulated to produce adrenocorticotropic hormone
3. ACTH travels to adrenal glands and stimulates the outer part ( adrenal cortex - zona faciculata) to produce cortisol steroid
   • Cortisol is a glucocorticoid which are not soluble in water
   • Cortisol is only lipid soluble so in blood most is bound to cortisol blinding globulin
   • Only 5 % is free in the blood and biologically active

Question 4

Function of cortisol

Answer 4

• Part of circadian rhythm - high in the morning
• Stress response by
1. Increase gluconeogenesis - synthesis of new glucose molecules
2. Proteolysis - breakdown of proteins
3. Lipolysis - break down of fats
4. Maintains blood pressure -increases senstivit of blood vessels to catcholamines ( epinephrine or norepinephrine)

Question 5

Cushing syndrome pathophys

Answer 5

cortisol levels are constantly higher than norma
l - severe muscle, bone and skin break dow
2. Elevated blood glucose - leading to high insulin levels and increase in adipose tissue causing central obesity
3. Hypertension - amplify catecholamine and cross react with mineralcorticoid receptors
4. Inhibit gonadotropin relelasing hormone - messing up ovarian and testicular function

Question 6

Causes of Cushing’s syndrome

Answer 6

1. Exogenous - outside medication
   • long period of steroid med - asthma/r arthritis
2. Endogenous - made by body
   • Excess ACTH - caused by pituitary adenoma benign
   • Small cell lung cancer
   • Tumors of adrenal gland

Question 7

Symptoms

Answer 7

1. Muscle wasting/ thin extremities
2. Easy brusing
   • oBESITY/ big abdomen
   • Hyperglycemia - diabetes mellitus/hypertension
3. Full moon shaped face
   • Buffalo hump - fatty hump on the upper back
   • Truncal obesity

Question 8

Exogenous steroid medication

Answer 8

• negative feedback on hypothalamus and pituitary gland
• shuts down cortisol production from zona faciculata
• Zona faciculata and shrink and become atrophic
• Causes adrenal gland to shrink and reduced exogenous production
• Still high levels of exogenous cortisol production