26 Questions
Which one of the following is a characteristic of Conn's syndrome?
Excess secretion of aldosterone
What is the effect of Conn's syndrome on water and electrolyte balance?
Increased water retention and decreased potassium excretion
How can a diagnosis of primary hyperaldosteronism be confirmed?
Measurement of plasma renin levels
Which enzyme is deficient in the case of 11 beta hydroxylase deficiency?
11 beta hydroxysteroid dehydrogenase
What is the expected level of serum 17-(OH)-progesterone in the case of 11 beta hydroxylase deficiency?
1000
What is the expected level of 24 h urine pregnanetriol in the case of 11 beta hydroxylase deficiency?
2.8
Will renin be elevated in the case of 11 beta hydroxylase deficiency?
Yes
Which of the following is a direct effect of aldosterone?
Increased thirst
Which of the following is a primary cause of hyperaldosteronism?
Adrenal adenoma
What is the primary stimulus for aldosterone secretion?
Low circulating volume
How can primary hyperaldosteronism be diagnosed?
All of the above
Which of the following is the primary stimulus for aldosterone secretion in the renin-angiotensin system?
Decreased renal blood flow
Which of the following is a consequence of excess aldosterone secretion?
Metabolic alkalosis
Which of the following factors independently stimulates aldosterone secretion?
Plasma potassium levels
What is the main role of aldosterone in the body?
Maintaining sodium and water balance
Which enzyme deficiency is the most common cause of Congenital Adrenal Hyperplasia (CAH)?
21 hydroxylase deficiency
Which hormone is primarily affected in CAH?
Cortisol
What is the main effect of severe 21 hydroxylase deficiency on aldosterone synthesis?
Variable effect on aldosterone synthesis
What is the main effect of severe 21 hydroxylase deficiency on androgen synthesis?
Increased androgen synthesis
Which of the following is a characteristic of adrenal adenomas and carcinomas compared to FHA and unilateral hyperplasia?
All of the above
Which gene is involved in the unequal crossing over between 11b hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) genes in Familial Hyperaldosteronism type I (FHI)?
Both CYP11B1 and CYP11B2
Which of the following drugs inhibits 11 beta hydroxysteroid dehydrogenase and can lead to increased aldosterone levels?
Liquorice
Which of the following is a common finding in primary hyperaldosteronism?
Low plasma potassium
What is the expected urine potassium level in a patient with an adrenal tumor causing primary hyperaldosteronism?
High
What is the cause of Liddle's syndrome?
Mutations in eNAC in renal tubule cells
What is the primary cause of hyperaldosteronism in Bartter's syndrome?
Impaired ADH responsiveness
Study Notes
Characteristics of Conn's Syndrome
- Hypertension and hypokalemia are characteristic of Conn's syndrome
- Conn's syndrome is a consequence of excess aldosterone secretion
Effect on Water and Electrolyte Balance
- Excess aldosterone secretion leads to water retention and potassium depletion
- This can result in hypokalemia and hypertension
Diagnosis of Primary Hyperaldosteronism
- Primary hyperaldosteronism can be diagnosed with adrenal vein sampling
- This is used to lateralize aldosterone secretion to one adrenal gland
11 Beta Hydroxylase Deficiency
- 11 beta hydroxylase deficiency is an autosomal recessive disorder
- 11 beta hydroxylase is an enzyme involved in cortisol synthesis
- Deficiency of this enzyme leads to increased levels of 17-alpha-hydroxyprogesterone
- This results in virilization and hypertension
Serum and Urine Levels in 11 Beta Hydroxylase Deficiency
- Serum 17-alpha-hydroxyprogesterone levels are elevated in 11 beta hydroxylase deficiency
- 24-hour urine pregnanetriol levels are also elevated in this condition
- Renin levels are decreased in 11 beta hydroxylase deficiency due to volume expansion
Effects of Aldosterone
- Aldosterone stimulates sodium reabsorption and potassium excretion in the distal nephron
- This leads to hypertension and hypokalemia
Causes of Hyperaldosteronism
- Primary hyperaldosteronism is caused by adrenal adenoma or carcinoma
- Secondary hyperaldosteronism is caused by renovascular disease or reninoma
Regulation of Aldosterone Secretion
- Aldosterone secretion is stimulated by angiotensin II, potassium, and ACTH
- The renin-angiotensin-aldosterone system is the primary regulator of aldosterone secretion
Diagnosis of Congenital Adrenal Hyperplasia (CAH)
- CAH is caused by 21 hydroxylase deficiency in 90% of cases
- CAH leads to virilization and ambiguous genitalia in females
Effects of 21 Hydroxylase Deficiency
- 21 hydroxylase deficiency leads to decreased aldosterone synthesis
- This results in salt wasting and hypotension
- 21 hydroxylase deficiency also leads to increased androgen synthesis
- This results in virilization and ambiguous genitalia in females
Adrenal Tumors
- Adrenal adenomas and carcinomas are frequently unilateral
- They are characterized by unilateral adrenal hyperplasia
Familial Hyperaldosteronism Type I (FHI)
- FHI is caused by unequal crossing over between CYP11B1 and CYP11B2 genes
- This results in the ectopic expression of aldosterone synthase in the adrenal zona fasciculata
Inhibitors of 11 Beta-Hydroxysteroid Dehydrogenase
- Glycyrrhetinic acid inhibits 11 beta-hydroxysteroid dehydrogenase
- This leads to increased aldosterone levels and hypertension
Primary Hyperaldosteronism
- Primary hyperaldosteronism is characterized by hypertension and hypokalemia
- Urine potassium levels are decreased in primary hyperaldosteronism
Liddle's Syndrome
- Liddle's syndrome is caused by activating mutations of the beta subunit of the epithelial sodium channel
- This results in excessive sodium reabsorption and hypertension
Bartter's Syndrome
- Bartter's syndrome is caused by mutations of the thick ascending limb of the loop of Henle
- This results in excessive potassium wasting and hypokalemia
Test your knowledge on aldosterone deficiency, deoxycorticosterone, virilization, hypertension, and urinary 17-hydroxycorticosteroids. Explore the differences from 11 b hydroxysteroid dehydrogenase and learn about pregnenolone, progesterone, 11-deoxycorticosterone, corticosterone, and aldosterone. Take the quiz now!
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