Cushing’s Syndrome and Addison’s Disease: Understanding Adrenal Gland Disorders and Their Impact on Health
Introduction
The adrenal glands play a vital role in regulating metabolism, immune function, blood pressure, and stress responses. Disorders affecting these glands can lead to significant health problems. Two major adrenal gland disorders are Cushing’s Syndrome and Addison’s Disease.
- Cushing’s Syndrome results from excessive cortisol production, often due to prolonged steroid use or adrenal tumors.
- Addison’s Disease occurs due to adrenal insufficiency, where the glands fail to produce sufficient steroid hormones.
This module explores the causes, symptoms, diagnosis, and management of these disorders.
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The Adrenal Glands: Structure and Function
- Located above each kidney, the adrenal glands consist of two main parts:
- Adrenal Cortex: Produces corticosteroids (cortisol, aldosterone) and androgens.
- Adrenal Medulla: Releases catecholamines (epinephrine and norepinephrine) in response to stress.
Role of Adrenal Hormones
- Cortisol: Regulates metabolism, immune responses, and stress adaptation.
- Aldosterone: Maintains sodium and potassium balance, influencing blood pressure.
- Androgens: Contribute to secondary sexual characteristics.
Cushing’s Syndrome: Causes and Symptoms
Causes
- Exogenous: Long-term corticosteroid medication use (iatrogenic Cushing’s syndrome).
- Endogenous: Overproduction of cortisol due to:
- Pituitary adenomas (Cushing’s disease)
- Adrenal tumors
- Ectopic ACTH-producing tumors (e.g., lung cancer)
Symptoms
- Physical changes:
- Weight gain, especially in the trunk
- Moon-shaped face, buffalo hump
- Purple stretch marks (striae) on the abdomen
- Metabolic and hormonal effects:
- High blood sugar, diabetes risk
- Hypertension
- Osteoporosis
- Psychological effects:
- Depression, anxiety, cognitive impairments
Diagnosis
- Hormonal Tests:
- 24-hour urinary free cortisol test
- Dexamethasone suppression test
- Late-night salivary cortisol test
- Imaging:
- MRI or CT scan of the adrenal or pituitary gland
Treatment
- Medication:
- Ketoconazole, metyrapone (to reduce cortisol production)
- Surgery:
- Pituitary or adrenal tumor removal
- Radiotherapy:
- For cases where surgery is not effective
Addison’s Disease: Causes and Symptoms
Causes
- Primary Adrenal Insufficiency (destruction of the adrenal cortex due to):
- Autoimmune disease (most common cause)
- Tuberculosis or infections
- Genetic disorders
- Secondary Adrenal Insufficiency:
- Pituitary failure leading to reduced ACTH production
Symptoms
- General symptoms:
- Chronic fatigue, muscle weakness
- Weight loss, low blood pressure
- Skin changes:
- Hyperpigmentation (darkening of the skin)
- Electrolyte imbalance:
- Low sodium, high potassium
- Dehydration risk
Diagnosis
- Hormonal Tests:
- ACTH stimulation test
- Serum cortisol measurement
- Electrolyte panel (to check sodium and potassium levels)
Treatment
- Hormone Replacement Therapy:
- Hydrocortisone or prednisone (for cortisol deficiency)
- Fludrocortisone (for aldosterone replacement)
- Emergency Management:
- Addisonian crisis (severe adrenal failure) requires immediate IV hydrocortisone and saline infusion.
Comparison of Cushing’s Syndrome and Addison’s Disease
| Feature | Cushing’s Syndrome | Addison’s Disease |
|---|---|---|
| Cortisol Levels | High | Low |
| Blood Pressure | High | Low |
| Weight Changes | Gain | Loss |
| Skin Changes | Thinning, striae | Hyperpigmentation |
| Electrolyte Balance | High sodium, low potassium | Low sodium, high potassium |
Prevention and Lifestyle Modifications
- Cushing’s Syndrome:
- Monitor steroid medication use under medical guidance
- Maintain a balanced diet and healthy weight
- Addison’s Disease:
- Regular monitoring of cortisol levels
- Wear a medical alert bracelet for emergencies
Further Reading
For more information, you can visit the following resources:
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Endocrine Society
- Mayo Clinic – Cushing’s Syndrome
- Mayo Clinic – Addison’s Disease
Conclusion
Cushing’s Syndrome and Addison’s Disease represent two extremes of adrenal dysfunction, with excessive cortisol in the former and insufficient hormone production in the latter. Early diagnosis and proper management are crucial to prevent complications and improve quality of life. Understanding these disorders allows for better awareness and proactive healthcare measures.
1. Which hormone is primarily overproduced in Cushing’s syndrome?
a) Insulin
b) Cortisol ✅
c) Aldosterone
d) Adrenaline
Explanation: Cushing’s syndrome results from excessive production of cortisol by the adrenal glands, leading to symptoms such as weight gain, high blood pressure, and muscle weakness.
2. What is the most common cause of Cushing’s syndrome?
a) Adrenal insufficiency
b) Pituitary adenoma ✅
c) Autoimmune disease
d) Excessive insulin production
Explanation: A pituitary adenoma can lead to excessive secretion of ACTH, stimulating the adrenal glands to produce too much cortisol, causing Cushing’s syndrome.
3. Which of the following is NOT a symptom of Cushing’s syndrome?
a) Moon face
b) Buffalo hump
c) Hyperpigmentation ✅
d) Hypertension
Explanation: Hyperpigmentation is a feature of Addison’s disease, not Cushing’s syndrome.
4. What is the primary cause of Addison’s disease?
a) Excess cortisol production
b) Autoimmune destruction of the adrenal cortex ✅
c) Pituitary adenoma
d) Overuse of glucocorticoids
Explanation: Addison’s disease is most commonly caused by autoimmune destruction of the adrenal cortex, leading to decreased production of cortisol and aldosterone.
5. Which hormone is deficient in Addison’s disease?
a) Cortisol ✅
b) Insulin
c) Growth hormone
d) Thyroxine
Explanation: Addison’s disease is characterized by insufficient cortisol production, leading to fatigue, weight loss, and low blood pressure.
6. Which of the following is a key symptom of Addison’s disease?
a) High blood pressure
b) Hyperglycemia
c) Skin hyperpigmentation ✅
d) Excessive hair growth
Explanation: Hyperpigmentation occurs due to increased ACTH levels stimulating melanocytes, leading to darkening of the skin.
7. What is the effect of Cushing’s syndrome on blood sugar levels?
a) Hypoglycemia
b) Hyperglycemia ✅
c) No effect
d) Hypotension
Explanation: Excess cortisol increases gluconeogenesis, leading to elevated blood sugar levels (hyperglycemia), which can contribute to diabetes.
8. Addison’s disease results in which electrolyte imbalance?
a) Hypernatremia and hypokalemia
b) Hyponatremia and hyperkalemia ✅
c) Hypercalcemia
d) Hypoglycemia only
Explanation: Due to decreased aldosterone, sodium is lost, and potassium is retained, causing hyponatremia and hyperkalemia.
9. What is a common feature of Cushing’s syndrome?
a) Muscle wasting ✅
b) Increased bone density
c) Weight loss
d) Increased ACTH levels always
Explanation: Excess cortisol causes protein breakdown, leading to muscle wasting and weakness.
10. The ‘buffalo hump’ in Cushing’s syndrome refers to:
a) Fat accumulation in the back of the neck ✅
b) Increased skeletal muscle mass
c) Enlarged thyroid gland
d) None of the above
Explanation: Cushing’s syndrome causes fat redistribution, leading to a characteristic ‘buffalo hump’ at the back of the neck.
11. The primary treatment for Addison’s disease is:
a) Insulin therapy
b) Glucocorticoid replacement ✅
c) Surgery
d) Chemotherapy
Explanation: Addison’s disease is treated with hormone replacement therapy, typically hydrocortisone.
12. The most common diagnostic test for Cushing’s syndrome is:
a) MRI
b) Dexamethasone suppression test ✅
c) ECG
d) Blood glucose test
Explanation: The dexamethasone suppression test assesses whether cortisol production is properly regulated.
13. Which of the following drugs is used to treat Cushing’s syndrome?
a) Ketoconazole ✅
b) Insulin
c) Metformin
d) Levothyroxine
Explanation: Ketoconazole inhibits cortisol synthesis and is used in Cushing’s syndrome treatment.
14. Which type of adrenal insufficiency results from pituitary damage?
a) Primary
b) Secondary ✅
c) Tertiary
d) None of the above
Explanation: Secondary adrenal insufficiency occurs due to decreased ACTH production by the pituitary gland.
15. Which gland regulates adrenal function through ACTH production?
a) Thyroid
b) Pituitary ✅
c) Pancreas
d) Hypothalamus
Explanation: The pituitary gland releases ACTH, which stimulates the adrenal glands to produce cortisol.
16. The adrenal cortex produces all EXCEPT:
a) Cortisol
b) Aldosterone
c) Epinephrine ✅
d) Androgens
Explanation: Epinephrine is produced by the adrenal medulla, not the cortex.
17. The primary role of aldosterone is:
a) Regulating glucose levels
b) Maintaining sodium and potassium balance ✅
c) Stimulating insulin release
d) Enhancing muscle growth
Explanation: Aldosterone regulates electrolyte and fluid balance by affecting sodium and potassium levels.
18. What triggers an Addisonian crisis?
a) Excess cortisol production
b) Severe stress or infection ✅
c) High blood sugar
d) Overuse of steroids
Explanation: In Addison’s disease, stress or infection can trigger a crisis due to the inability to produce enough cortisol.
19. Which of the following conditions is associated with Cushing’s syndrome?
a) Osteoporosis ✅
b) Hypotension
c) Hypoglycemia
d) Decreased appetite
Explanation: Cortisol excess leads to decreased bone density, increasing the risk of osteoporosis.
20. Which symptom differentiates Addison’s disease from secondary adrenal insufficiency?
a) Hyperpigmentation ✅
b) Fatigue
c) Weight loss
d) Low blood pressure
Explanation: Hyperpigmentation occurs due to high ACTH levels in primary adrenal insufficiency but is absent in secondary adrenal insufficiency.
21. Which enzyme is responsible for cortisol synthesis?
a) 11β-hydroxylase ✅
b) Amylase
c) Trypsin
d) Pepsin
Explanation: 11β-hydroxylase is essential for cortisol biosynthesis.
22. What is the normal cortisol secretion pattern?
a) Peaks at midnight
b) Peaks in the morning ✅
c) Constant throughout the day
d) Random
Explanation: Cortisol follows a circadian rhythm, with peak levels in the morning.
23. The best test for diagnosing Addison’s disease is:
a) ACTH stimulation test ✅
b) CT scan
c) X-ray
d) EEG
Explanation: The ACTH stimulation test measures the adrenal gland’s response to ACTH, diagnosing Addison’s disease.
