1: Fluid and Electrolyte - Hypernatraemia Flashcards
How can aetiology of hypernatraemia be divided
Hypovolaemic
Euvolaemic
Hypervolcaemic
What causes hypovolaemia hypernatraemia
- Dehydration
- Diuretics
- Osmotic diuresis (Glucose)
What causes euvolaemic hypernatraemia
- Diabetes inspidus
What causes hypervolaemic hypernatraemia
- Primary hyperaldosteronism (Conns)
- Cushing’s disease
- Iatrogenic
Explain presentation of sub-acute hypernatraemia
In sub-acute cells have time to adjust and release osmotic particles increasing water retention
Explain acute (<48h) presentation of hypernatraemia
Cells to not have time to adjust - meaning water moves into vascular space to compensate for sodium. This causes shrinkage and lysis of cells
How does mild hypernatraemia present
- Muscle weakness
- Headache
- N+V
How does moderate hypernatraemia present
- Muscle weakness
- Lethargy
- Confusion
How does severe hypernatraemia present
- Coma
- Altered consciousness
- Seizures
What is first line investigation for hypernatraemia
U+E
What will be seen on U+E
High Sodium
If hypernatraemia is seen what should be ordered
Urine osmolality
What does a serum osmolality of less than 800 imply
Less than 800 implies excessive water loss via the kidneys
What does serum osmolality more than 800 imply
More than 800 implies extra-renal water loss. Kidney tries to compensate by increasing water reabsorption and concentrating urine
What does a serum osmolality less than 800 and hypovolaemia indicate
- Diuretics = increase fluid excretion by kidney
- Osmotic diuresis
What does a serum osmolality less than 800 and euvolaemia indicate
Diabetes inspidus
What does serum osmolality less than 800 and hypervolaemia indicate
Conns
Cushing’s syndrome
What does urine osmolality more than 800 and hypovolaemic indicate
Vomitting
Diarrhoea
What does urine osmolality and euvolaemic indicate
Impaired thirst
What does urine osmolality and hypervolaemic indicate
Iatrogenic - excess sodium chloride
How is mild hypernatraemia managed
Increase oral fluids
How is moderate hypernatraemia managed
IV Fluid
What IV fluid is given if acute hypernatraemia
5% Dextrose
What IV fluid is given if sub-acute hypernatraemia
NaCl
What does too rapid correction of hypernatraemia cause
Cerebral oedema
How does cerebral oedema present
- Seizures
- Coma
