Endocrine - Potassium

Question 1

Differential for hypokalaemia and hypertension?

Answer 1

Cushings

Conn’s syndrome (= primary hyperaldosteronism)

Liddle’s Syndrome

11-beta hydroxylase deficiency

Carbenoxolone (anti ulcer drug)

Licquorice Excess

Question 2

What is Liddle Syndrome?

• inheritance and chromosome
• what goes wrong
• features
• lab findings

Answer 2

Autosomal dominant
Chromosome 16

Excessive activity of amiloride sensitive sodium channels in the COLLECTING TUBULE

Features:

• hypertension
• hypokalaemia
• metabolic acidosis

LABS:

• low renin
• low plasma aldosterone
• low urine aldosterone

Question 3

Differential for hypokalaemia and normotension

Answer 3

Diuretics

GI loss

Renal Tubular Acidosis Types 1 and 2

Gitelman Syndrome

Bartter Syndrome

Question 4

What is Bartter Syndrome?

• inheritance
• what goes wrong?
• labs

Answer 4

Autosomal recessive

Defect in Na/K/2Cl cotransporter in ascending loop of henle

LABS:
- metabolic alkalosis
- hypercalciuria
\+/- hypomagnesaemia
- increased urine prostaglandin E
- increased renin
- increased prostagladins

Question 5

What is Gitelman Syndrome?

• inheritance
• which gene
• what goes wrong
• labs

Answer 5

Autosomal recessive

Gene involved: NCCT gene

Defect in thiazide sensitive NaCl transporter in DCT

LABS

• metabolic alkalaosis
• hypocalciuria
• hypomagnesaemia
• increased renin
• increased aldosterone
• NORMAL urine prostaglandin E

Question 6

Gitelman, Barter and Liddles:

changes in urine prostaglandins?

Answer 6

Bartter: Incresaed urine prostaglandin E

Gitelman: normal urine prostaglandin E

Question 7

Gitelman, Barter and Liddles:

changes in renin and aldosterone?

Answer 7

Increased renin and aldosterone in Gitelman

Increased renin in Bartter

Decreased renin and aldosterone in Liddles

Question 8

Difference between Thyrotoxic Periodic Paralysis versus Familial Hypokalaemic Periodic Paralysis

• age of onset
• ethnicity
• duration of attacks
• clinical course

Answer 8

Age of onset:
Thyrotoxic Periodic Paralysis: 20-45yrs
Familial Hypokalaemic Periodic Paralysis: <16yrs

Ethnicity:
Thyrotoxic Periodic Paralysis: Asian
Familial Hypokalaemic Periodic Paralysis: Caucasian

Duration of attacks:
Thyrotoxic Periodic Paralysis: 30 mins - 6 hours
Familial Hypokalaemic Periodic Paralysis: >24 hours

Clinical course:
Thyrotoxic Periodic Paralysis: Remits after thyrotoxicosis is corrected
Familial Hypokalaemic Periodic Paralysis: Chronic myopathy

Question 9

Gene associated with Thyrotoxic Periodic Paralysis

Answer 9

Mutation in skeletal muscle potassium Kir2.6 channel in 33%

Question 10

Gene associated with Familial Hypokalaemic Periodic Paralysis

Answer 10

Mutation in skeletal muscle calcium and sodium channels in 80% (Cav1.1) and 15% (Nav1.4)

Question 11

Causes of hyperkalaemia?

Answer 11

acute kidney injury

drugs

• potassium sparing diuretics
• ACE inhibitors
• angiotensin 2 receptor blockers
• spironolactone
• ciclosporin
• heparin** (due to inhibition of aldosterone secretion)
• metabolic acidosis
• Addison’s
• rhabdomyolysis
• massive blood transfusion

Question 12

Hypokalaemia with Alkalosis?

Answer 12

Vomiting
Diuretics
Cushings Syndrome
Conn’s Syndrome (primary hyperaldosteronism)

Question 13

Hypokalaemia with acidosis?

Answer 13

Diarrhoea
Renal tubular acidosis
Acetazolamide
Partially treated DKA