Sodium Flashcards
What is the Edelman equation?
P[Na] = 1.11 x (Na + K)/(TBW) -25.6
Loss of the pituitary bright spot on MRI is indicative of what pathology?
Central Diabetes Mellitus
How does hypocortisolism produce hyponatraemia?
Hypocortisolaemia results in an increase in the synthesis of CRH which is co-expressed with ADH
How much solute does a kidney need for every 1L of free water?
50-100mOsm
How does 1.5% glycine irrigation cause hypoNa?
- Hypotonic fluid
- Stimulates ADH
What is the cause of the nephrogenic syndrome of inappropriate ADH?
- X-linked
- Gain of function in V2 receptor
- Carriers have abnormal response to water loading test
How do ACEi cause hyponatraemia?
- Use of ACEi increases the levels of Angiotensin 1
- Angiotensin 1 is converted to Angiotensin 2 in the brain
- AT2 releases ADH and stimulates thirst
In whom is fluid restriction unlikely to be an effective therapy for SIADH?
- High UOsm >500
- UNa + Uk / SNa >1
- Baseline urine volume <1500ml/d
What is the equation for Cosm
Cosm = Uosm x V / Posm
What is the equation for Osmolar Free Water Clearance?
OFWC = V x [1 - (Uosm/ Sosm)]
What is the equation for Electrolyte free water clearance?
EFWC = V x (1- (Una + Uk/ Sna))
What are the causes of nephrogenic DI?
- Hereditary nDI
- Hypercalcaemia
- Hypokalaemia
- Pregnancy
- Lithium
- Demeclocycline
- Methoxyflurane
- Foscarnet
- Aminoglycosides
- Amphotericin B
- Cidofovir
- Vaptans
What is the management of adipsic DI?
- DDAVP
What diuretic can be used in the management of nDI?
- Thiazides via TGF
What is the official definition of polyuria?
- urine volume >40ml/kg body weight/day
