Classification
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Hyponatraemia |
Hypernatraemia |
| Hypervolaemia |
- Total body sodium is HIGH
- Heart failure
- Triple diuretic therapy => Natriuresis
- Liver failure
- Treat with FLUID RESTRICTION
|
- Doctor's fault
- Treat with dialysis
|
| Euvolaemia |
- SIADH
- => Mild hypervolaemia
- Activates natriuresis => Euvolaemia
- Low serum Osm, High urine Osm
- SAME PICTURE as in heart failure, diarrhoea
- => MUST check urine [Na] too
- MUST exclude the 4 failures
- Heart, kidney, liver, adrenal
- Causes of SIADH
- Head
- Chest
- SCLC
- Pneumonia
- Abscess
- TB
- Empyaema
- Drugs ("The anti's")
- -psychotics
- -convulsants (beware of causing more fits!)
- -depressants
- -diuretics
- Treatment of SIADH
- Fluid restriction
- Vasopressin desensitisors
- Vaptans (incredibly expensive)
|
- Diabetes insipidus
- Treat with desmopressin
|
| Hypovolaemia |
- Thiazide diuretics
- Burns
- D+V
- Endocrine
- Addison's (unmasked by Hx of trauma?)
- Diabetes (osmotic diuresis)
- Cerebral salt wasting
|
- Total body sodium is LOW
- Therefore same causes as hypovolaemic hyponatraemia
|
Central pontine myelinolysis
- Affects CN III - VII
- Characteristic feature is gaze palsies
- Conjugate (complex) palsy
- INO
- Also:
- Long tract signs (spasticity)
- Reduced level of consciosuness
Marathons - Perfect storm:
- Complete loss of glycogen
- Rise in vasopressin
- Hypotonic fluids
- Treat with twice-normal saline
Notes
- Vasopressin is a STRESS HORMONE
- Hyponatraemia in marathons
- Hyponatraemia with MDMA
- Never give sodium or fluids together with diuretics
- Never give hyperosmolar saline without consultant approval
- Kidneys filter per day:
- 180 L of fluid
- 2 kg of NaCl
- Correct sodium at no more than 8 mM per day
- Use no more than 500 ml saline per day
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