SIADH

Question 1

what is SIADH

Answer 1

syndrome of inappropriate ADH production

excess production of antiduiretic hormone (ADH) and may be caused by a primary pituitary pathology, or a non-pituitary pathology

Question 2

causes of SIADH

Answer 2

Pituitary tumour

Tumours: small cell lung cancer, thymoma, lymphoma

Pulmonary disease: infections, pneumothorax, asthma, cystic fibrosis

CNS disease: infection, head injury

Drugs: chemotherapy, psychiatric drugs

Idiopathic

Question 3

what is the main feature of SIADH

Answer 3

hyponatraemia

Question 4

other causes of hyponatraemia

Answer 4

dehydration (hypovolaemia), Addisons

Question 5

symptoms of SIADH

Answer 5

mainly the symptoms of SIADH

muscle cramps, Nausea and vomitting, confusion, coma and seizures

Question 6

investigations to do for SIADH

Answer 6

Urea and electrolytes: shows hyponatraemia

Plasma osmolality: will be low (<270mOsm/kg)

Urine sodium: will be high (>20mmol/L)

Urine osmolality: will be inappropriately concentrated (>100mOsmol/kg)

Imaging: MRI brain for pituitary tumour

Question 7

management of SIADH

Answer 7

fluid restriction or diuretics

surgery if needed