SIADH

Question 1

What does SIADH stand for ?

Answer 1

(Syndrome of Inappropriate ADH)

Question 2

What is SIADH ?

Answer 2

SIADH, is an inappropriate secretion of antidiuretic hormone (ADH).
ADH is a hormone that helps control sodium concentration and blood pressure by adjusting the amount of water reabsorption by kidneys.
SIADH causes body to secrete too much ADH. When ADH levels are high, kidneys hold onto extra water even though you don’t need it and leads to hyponatremia(Low sodium in blood). The higher the ADH the more concentrated is urine.

Question 3

Why may SIADH occur ?

Answer 3

May result from
Any CNS abnormality – Stroke, haemorrhage, infection, trauma, mental illness, Psychosis
Heart failure or diseased hypothalamus (e.g. tumour)
Often associated with small cell carcinomas lung as cells may produce ‘ectopic’ ADH

Question 4

What are signs and symptoms of SIADH ?

Answer 4

• Lethargy & weakness
• Confusion or changes in
• neurological status
• Cerebral oedema
• Muscle cramps
• Decreased urine output
• Weight gain
• Hypertension

Question 5

What is treatment for SIADH ?

Answer 5

• Limit water intake
• Drugs to reduce fluid retention
• Increase blood sodium level (slowly, to avoid rapid changes in Na that may cause demyelination of neurons)
• Treatment of underlying cause e.g. small cell carcinoma of the lungs