cortisol

Question 1

Q

Answer 1

A

Question 2

What is the primary physiological function of cortisol?

Answer 2

To increase blood glucose levels (gluconeogenesis), provide anti-inflammatory effects, and help the body respond to stress.

Question 3

Where is cortisol produced and secreted from?

Answer 3

The zona fasciculata of the adrenal cortex.

Question 4

What is the primary regulator of cortisol release?

Answer 4

ACTH (Adrenocorticotropic Hormone) from the anterior pituitary, which is itself regulated by CRH (Corticotropin-Releasing Hormone) from the hypothalamus.

Question 5

Describe the circadian rhythm of cortisol secretion.

Answer 5

Highest in the early morning (around 8 AM)

Question 6

What is the mechanism of action of cortisol?

Answer 6

It is a lipid-soluble hormone that binds to intracellular glucocorticoid receptors, translocates to the nucleus, and alters gene transcription (increases or decreases mRNA synthesis).

Question 7

What are the key metabolic effects of cortisol?

Answer 7

1. Increases gluconeogenesis in the liver. 2. Promotes protein catabolism in muscle. 3. Promotes lipolysis in adipose tissue. 4. Permissive effect on glucagon and catecholamines.

Question 8

How does cortisol affect the immune system?

Answer 8

It is a potent anti-inflammatory and immunosuppressive agent: inhibits phospholipase A2, decreases cytokine production, and reduces lymphocyte proliferation.

Question 9

What is the effect of cortisol on blood glucose?

Answer 9

It increases blood glucose levels (diabetogenic effect) by reducing glucose uptake in tissues and promoting gluconeogenesis.

Question 10

What is the effect of cortisol on bone metabolism?

Answer 10

It inhibits bone formation by decreasing osteoblast activity and collagen synthesis. Chronic excess leads to osteoporosis.

Question 11

How does cortisol affect electrolyte balance (compared to aldosterone)?

Answer 11

It has weak mineralocorticoid activity. In high doses, it can cause sodium retention and potassium loss (similar to aldosterone).

Question 12

What is the role of Cortisol in fetal lung development?

Answer 12

It stimulates the production of surfactant, promoting lung maturity in the fetus.

Question 13

What is Addison’s disease and its hallmark lab findings?

Answer 13

Primary adrenal insufficiency. Hallmark: Low cortisol, High ACTH (due to lack of negative feedback), Hyponatremia, Hyperkalemia, Hypoglycemia.

Question 14

What is Cushing’s syndrome and its hallmark lab findings?

Answer 14

Condition of chronic cortisol excess. Hallmark: High cortisol, Low ACTH (if exogenous or adrenal tumor) or High ACTH (if pituitary source). Features: hyperglycemia, central obesity, moon face, muscle wasting.

Question 15

What is the purpose of the Dexamethasone Suppression Test?

Answer 15

To diagnose the cause of Cushing’s syndrome. Low-dose dexamethasone should suppress cortisol in normal individuals but not in Cushing’s. High-dose helps differentiate pituitary (suppresses) from ectopic (no suppression) sources.

Question 16

Which cytokine is a potent stimulator of the HPA axis and can increase cortisol levels?

Answer 16

Interleukin-6 (IL-6). Inflammation and stress can activate the HPA axis via cytokines.

Question 17

What is the difference between a ‘stress’ dose and a ‘physiological’ dose of hydrocortisone?

Answer 17

A stress dose (e.g., during surgery, infection) is much higher (2-3x) to mimic the body’s increased demand for cortisol. A physiological dose is for replacement therapy in insufficiency.

Question 18

A 40-year-old woman presents with weight gain

Answer 18

“moon facies”

Question 19

A patient with known asthma on long-term

Answer 19

high-dose prednisone therapy presents with back pain and a vertebral fracture. What is the most likely mechanism for this finding?

Question 20

A patient with suspected adrenal insufficiency (Addison’s disease) undergoes a cosyntropin (ACTH) stimulation test. What result would confirm the diagnosis?

Answer 20

No rise in serum cortisol levels after ACTH administration. This indicates the adrenal glands are incapable of producing cortisol.

Question 21

What is the expected effect of a sudden

Answer 21

high dose of exogenous cortisol on the blood levels of ACTH and CRH?

Question 22

A premature infant is at risk for Respiratory Distress Syndrome (RDS). Which hormone is often administered prenatally to the mother to help accelerate fetal lung maturity?

Answer 22

Cortisol (or betamethasone, a synthetic analog). It stimulates surfactant production in type II pneumocytes.

Question 23

A patient presents with weakness

Answer 23

fatigue

Question 24

In the context of the stress response

Answer 24

which of the following is a primary effect of elevated cortisol levels that helps maintain blood pressure?

Question 25

A patient with Cushing's syndrome has a low-dose dexamethasone test that shows no suppression. A high-dose dexamethasone test shows a >50% suppression of cortisol. What is the most likely cause?

Answer 25

Cushing's Disease (pituitary adenoma). Pituitary sources often suppress with high-dose dexamethasone, while adrenal tumors and ectopic ACTH sources do not.