Adrenal Gland and Corticosteroids

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Questions and Answers

What is the primary function of the zona glomerulosa in the adrenal gland?

To produce mineralocorticoids (correct)

To produce catecholamines

To produce glucocorticoids

To produce androgens

What is the normal daily secretion of cortisol in adults?

20-30 mg

5-10 mg

10-20 mg (correct)

30-40 mg

What is the peak time of cortisol secretion in a normal adult?

4 AM

12 AM

8 AM (correct)

12 PM

What is the primary regulator of adrenal steroid hormone synthesis?

Hypothalamic-Pituitary-Adrenal axis Signup and view all the answers

What is the hormone released by the hypothalamus that stimulates the synthesis and release of ACTH?

Corticotropin-releasing hormone (CRH) Signup and view all the answers

What is the precursor molecule for the synthesis of cortisol and aldosterone?

Cholesterol Signup and view all the answers

What is the enzyme responsible for the conversion of 11-desoxycorticosterone to corticosterone?

11,β-hydroxylase Signup and view all the answers

What is the normal plasma concentration of aldosterone in adults?

0.01 mcg/dl Signup and view all the answers

What is the primary function of aldosterone in the human body?

To maintain water and electrolyte balance Signup and view all the answers

In which disease is dexamethasone commonly used to promote lung maturation?

Respiratory distress syndrome in premature infants Signup and view all the answers

What is a common side effect of glucocorticoids on the musculoskeletal system?

Myopathy and muscle wasting Signup and view all the answers

Which of the following is an absolute contraindication for glucocorticoid therapy?

Cushing's disease Signup and view all the answers

What is the mechanism by which glucocorticoids prevent graft rejection in organ transplants?

By inhibiting the host immune system Signup and view all the answers

Which of the following is a common behavioral change associated with glucocorticoid therapy?

Hypomania or acute psychosis Signup and view all the answers

What is the purpose of using glucocorticoids in the treatment of nephrotic syndrome?

To treat the underlying inflammatory condition Signup and view all the answers

What is a common side effect of glucocorticoids on the eye?

All of the above Signup and view all the answers

What is the primary effect of ACTH binding to its receptor on the adrenal cortex?

Induction of genes involved in adrenal steroid hormone synthesis Signup and view all the answers

What is the effect of cortisol on glucose metabolism in the periphery?

Decreased peripheral glucose utilization Signup and view all the answers

What is the result of cortisol's effect on lipid metabolism?

Increased lipolysis and glycerol production Signup and view all the answers

What is the physiological response to increased cortisol levels during stress?

Increased glucose supply to glucose-dependent tissues Signup and view all the answers

What is the negative feedback mechanism of cortisol on the HPA axis?

Inhibition of CRH and ACTH production Signup and view all the answers

What is the characteristic distribution of fat in response to cortisol?

Redistribution of fat to the truncal region and upper chest Signup and view all the answers

What is the primary protein that glucocorticoids bind to in plasma?

Corticosteroid binding globulin (CBG) Signup and view all the answers

What is the half-life of corticosteroids in a healthy individual?

60-90 minutes Signup and view all the answers

Why is prednisone preferred in pregnancy?

It minimizes steroid effects on the fetus Signup and view all the answers

What is the primary use of fludrocortisone in replacement therapy for adrenocortical insufficiency?

To supplement mineralocorticoid deficiency Signup and view all the answers

What is the effect of dexamethasone on cortisol release in normal individuals?

It suppresses cortisol release Signup and view all the answers

What is the reason for dividing the daily dose of hydrocortisone in replacement therapy for primary adrenocortical insufficiency?

To mimic the natural circadian rhythm Signup and view all the answers

What is the effect of hepatic dysfunction on the half-life of corticosteroids?

It increases the half-life Signup and view all the answers

What is the primary reason for using glucocorticoids in the treatment of rheumatoid disorders?

To suppress the immune response Signup and view all the answers

Which of the following factors has a moderate stimulating effect on aldosterone secretion, but only lasts for a few days?

ACTH Signup and view all the answers

What is the half-life of desoxycorticosterone?

70 minutes Signup and view all the answers

What is the primary use of fludrocortisone?

Treatment of adrenocortical insufficiency Signup and view all the answers

Which of the following inhibitors of adrenocorticoid biosynthesis is used to treat patients with Cushing syndrome?

Ketoconazole Signup and view all the answers

What is the primary mechanism of action of spironolactone?

Competing for the mineralocorticoid receptor Signup and view all the answers

What is the daily dose of fludrocortisone used in replacement therapy?

50-200 μg/day Signup and view all the answers

What is the amount of aldosterone excreted free or glucoronoid per day?

5-15 μg/24 hours Signup and view all the answers

What is the daily secretion of desoxycorticosterone?

200 μg/day Signup and view all the answers

Study Notes

Adrenal Gland Structure

The adrenal gland consists of two parts: Cortex and Medulla
Cortex is responsible for producing Adrenal Steroids or Corticosteroids
Medulla produces Catecholamines

Corticosteroids Synthesis

Both cortisol and aldosterone are synthesized from cholesterol
Normal adults secrete 10-20 mg of cortisol daily and 0.125 mg of aldosterone daily
The rate of secretion of cortisol is controlled by a circadian rhythm that peaks at 8 AM

Cortisol Plasma Concentration

Cortisol plasma concentration is 16 mcg/dl at 8 AM and 4 mcg/dl at 4 PM
Aldosterone plasma concentrations are constant at 0.01 mcg/dl

Hypothalamic-Pituitary-Adrenal (HPA) Axis

The HPA axis regulates the synthesis of adrenal steroid hormones
Corticotropin-releasing hormone (CRH) is released by the hypothalamus in response to circadian rhythms and stress inducers
CRH acts on the cells of the corticotropes of the Anterior Pituitary to induce the synthesis and release of adrenocorticotrophic hormone (ACTH)

Physiological Effects of Glucocorticoids

Carbohydrate and Protein Metabolism

Liver: ↑gluconeogenesis and ↑glycogen storage
Periphery: ↑protein catabolism = ↑ substrate for gluconeogenesis
↓ peripheral glucose utilization
↑ blood glucose

Lipid Metabolism

↑ lipolysis by facilitating action of GH/B-adrenergic agents
↑ glycerol = ↑ substrate for liver gluconeogenesis
↑ FFA contributes to ↑ insulin resistance
Redistribution of fat: ↑ truncal obesity, ↑ back of neck (buffalo hump)/upper chest, ↑ moon facies, ↓ extremities

Response to Stress

Cortisol levels increase in times of stress
The corresponding increase in blood glucose acts to protect glucose-dependent tissues

Pharmacological Uses

Endocrine Uses of Glucocorticoids

Replacement therapy for primary adrenocortical insufficiency (Addison disease)
Replacement therapy for secondary or tertiary adrenocortical insufficiency
Diagnosis of Cushing syndrome
Replacement therapy for congenital adrenal hyperplasia

Non-Endocrine Uses of Glucocorticoids

Rheumatoid disorders (e.g., RA, SLE, vasculitis)
Treatment of allergies
Organ transplants (prevents graft rejection by inhibiting host immune system)
Kidney (treats nephrotic syndrome)
Treatment of inflammatory conditions (e.g., skin, inflammatory eye diseases, GI tract, inflammatory bowel disease, and ulcerative colitis)
Cancer (treatment of acute lymphocytic leukemias and lymphomas)

Toxicity

Immune response: increased susceptibility to infections
Risk of peptic ulcers
Myopathy & muscle wasting
Osteoporosis
Hyperglycemia
Behavioral changes: hypomania or acute psychosis
Cataracts (posterior subcapsular), glaucoma
Fluid & electrolyte balance: Na retention, HT, hypokalemia
HPA Axis suppression
Others: acne, thinning of skin, purple striae, hirsutism, menstrual abnormalities, weight gain, pancreatitis

Mineralocorticoids

Aldosterone
Desoxycorticosterone
Fludrocortisone (synthetic corticosteroid, the most commonly used salt-retaining hormone)

Inhibitors of Adrenocorticoid Biosynthesis or Function

Ketoconazole (an antifungal agent that strongly inhibits all gonadal and adrenal steroid hormone synthesis)
Spironolactone (antihypertensive drug that competes for the mineralocorticoid receptor and inhibits sodium reabsorption in the kidney)

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Description

Quiz about the adrenal gland, its structure, and the synthesis of corticosteroids, including cortisol and aldosterone.