SiADH

Question 1

What is SiADH?

Answer 1

Syndrome of inappropriate ADH
- Excessive production

Question 2

What is the pathophysiology of SiADH?

Answer 2

Excessive ADH results in excessive water reabsorption in the collecting ducts
Water dilutes sodium in the blood causing hyponatraemia
Urine becomes concentrated causing high urine osmolarity and high urine sodium

Question 3

What are the symptoms of SiADH?

Answer 3

Headache
Fatigue
Muscle aches and cramps
Confusion
Severe hyponatraemia causes seizures and reduced consciousness

Question 4

What are the causes of SiADH?

Answer 4

Post-op
Infection
head injury
Medications
Malignancy e.g. small cell lung cancer
Meningitis

Question 5

What is the diagnosis of SiADH?

Answer 5

Exclude other causes of hyponatraemia:
- Addison’s
- Diuretic use
- Diarrhoea, vomiting
- Excessive water intake
- Kidney disease

Question 6

What is the management of SiADH?

Answer 6

Treat the cause
Fluid restriction
ADH receptor blockers
Antibiotics that inhibit ADH