2: SIADH Flashcards
Where is ADH released from
Posterior pituitary gland
What is SIADH
Syndrome excess ADH secretion
What are the 5 aetiological categories of SIADH
- Malignancy
- Neurological
- Infection
- Medication
- Other
What 3 malignancies can cause SIADH
- Pancreatic cancer
- Prostate cancer
- Squamous cell carcinoma
What are 4 neurological causes of SIADH
- SAH
- Subdural haemorrhage
- Stroke
- Meningitis
What other metabolic anomaly can occur following trauma or cerebral tumours
Cerebral salt waisting
What is cerebral salt wasting
Loss of sodium and hence water following tumour or trauma
What medications can cause SIADH
- Sulfonylurea
- SSRI
- Tricyclines
- Carbamazepine
- Vincristine
What is another cause of SIADH
PEEP
What are 4 mild symptoms of SIADH
- Nausea and Vomiting
- Anorexia
- Headache
- Muscle Cramps
What are 3 moderate symptoms of SIADH
- Muscle weakness
- Lethargy
- Confusion
What are 2 severe symptoms of SIADH
- Seizures
- Altered consciousness
What is the MOA of ADH on the kidney
ADH increases aquaporin-2 channels and water re-absorption
What metabolic abnormality is found in SIADH and why
Dilutional hyponatraemia
What is a complication of SIADH
Causes cerebral oedema- which can lead to raised ICP
What investigations are ordered in SIADH
U+E
Serum osmolality
Urine osmolality
How wil U+E present
Hyponatraemia
Due to increase water retention
Describe plasma osmolality
Low - secondary to dilution
Describe urine osmolality
High - due to increased water reabsorption concentrating urine
Describe urine sodium excretion
High
If asymptomatic how is SIADH managed
Restrict fluid-intake
If symptomatic, how is SIADH managed
- Hypertonic Saline Solution (Correct Sodium)
2,. Fluid Restriction
- Demeclocycline
Why should hypertonic saline solution be infused slowly
Avoid cerebral pontine myelinolysis - caused by too rapid correction of hyponatraemia
What is demeclocycline
Reduces sensitivity of renal collecting tubules to ADH
