Hyponatremia Flashcards
What is hyponatremia
Serum concentration of Na lower than 135mmol
How does a patient with hyponatremia commonly present
Patients with hyponatremia commonly present with neurological problems
May have lowered mini mental score, ataxic gait, past pointing, intention tremor, etc
May be agitated, nauseous
What tests should you undertake if a patient has hyponatremia
Serum osmolarity
Urine osmolarity
Urine Na
What are the causes of hyponatremia
True Na loss:
- D&V
- Diuretics
- Peritonitis
- Burns/CF
Na/water imbalance - most common cause. Relative hyponatremia:
- Imbalance in ADH secretion due to HF, kidney disease, liver disease, medication, tumour
- Drugs - thiazide and loop diuretics, anti-depressents, proton pump inhibitors, iACE
Which cells are particularly sensitive to changes in plasma osmolarity
Neurones are particularly sensitive -> neurological problems often seen with changes in plasma osmolarity
What is the most common osmolarity of a patient with hyponatremia
Patients with hyponatremia are commonly hypo-osmotic
What symptoms would a patient with hyponatremia have if they were hypo-osmotic and oedematous
They would have the same symptoms as HF:
- Fatigue
- Ascites
- Hepatosplenamegaly
- Increased peripheral resistance
- Distended jugular veins
- Anorexia
- GI distress
- Weight gian
- Dependent oedema
What are the non-renal causes of a hypovolemic, hyponatraemic patient
GI losses - vomiting, diarrhoea, fistula, pancreatitis
Excessive sweating
Third spacing of fluids - ascites, pancreatitis, peritonitis, burns
Cerebal salt-wasting syndrome - injury to the brain causing increased salt and fluid loss
What is the main treatment of hyponatremia
Fluid restriction - nearly always works
What would be the cause of urine Na < 10mmol/L with hypovolaemia
GI/skin loss
What would be the cause of urine Na < 10mmol/L with hypervolaemia
CCF (congested cardiac failure)
Nephrotic syndrome
Liver failure
(HF)
What would be the cause of urine Na > 20mmol/L with hypovolaemia
Renal loss
What would be the cause of urine Na > 20mmol/L with hypervolaemia
Renal failure
What would be the cause of urine Na > 20mmol/L with euvolaemia
SIADH
