Endocrine (+ Electrolytes)

Question 1

Causes of hypokalaemia with hypertension

Answer 1

Cushing's syndrome
Conn's syndrome (primary hyperaldosteronism)
Liddle's syndrome
11-beta hydroxylase deficiency*
(Carboxolone & Liquorice as well)

Question 2

Causes of hypokalaemia without hypertension

Answer 2

Diuretics
GI loss (e.g. Diarrhoea, vomiting)
Renal tubular acidosis (type 1 and 2**)
Bartter's syndrome
Gitelman syndrome

Question 3

Causes of hyponatraemia (Urinary Na >20, Hypovolameic)

Answer 3

Diuretics (thiazides & loop)
Addisons disease
Diuretic stage of renal failure

Question 4

Causes of hyponatraemia (Urinary Na >20, Euvolaemic)

Answer 4

SIADH

Hypothyroidism

Question 5

Causes of hyponatraemia (Urinary Na <20, Hypovolaemic)

Answer 5

D+V
Sweating
Burns
Adenoma of rectum

Question 6

Causes of hyponatraemia (Urinary Na <20, Hypervolaemic)

Answer 6

Secondary hyperaldosteronism (eg liver cirrhosis/heart failure)
Renal failure
IV dextrose
Psychogenic polydipsia

Question 7

Causes of SIADH

Answer 7

Characterised by hyponatraemia secondary to dilutional effects of excess water retention

Malignancy -> Small cell lung cancer
-> Also: pancreas, prostate

Neurological -> Stroke

                   - > Subarachnoid haemorrhage
                   - > Subdural haemorrhage
                   - > Meningitis/encephalitis/abscess

Infections -> Tuberculosis
-> Pneumonia

Drugs -> Sulfonylureas*

       - > SSRIs, tricyclics
       - > Carbamazepine
       - > Vincristine
       - > Cyclophosphamide

Other causes -> Positive end-expiratory pressure
-> Porphyrias

Question 8

Management of SIADH

Answer 8

• > Correction must be done slowly to avoid precipitating central pontine myelinolysis
• > Fluid restriction
• > Demeclocycline: reduces the responsiveness of the collecting tubule cells to ADH
• > ADH (vasopressin) receptor antagonists have been developed