Endocrinology: Acute Hypernatraemia Flashcards
Outline the pathophysiology of Hypernatraemia
> 145 mmol/l
Outline the aetiology of hypernatraemia
Hypovolaemic
- Diuretics = mainly loop diuretics
- Dehydration = diarrhoea, vomiting, burns, excessive sweating
- Acute tubular necrosis
- Hyperosmolar states = includes hyperosmolar hyperglycaemic state
Euvolemia:
- Diabetes insipidus (DI)
Hypervolemic:
- Excessive hypertonic saline administration (common)
- Steroid excess = Conn’s syndrome or Cushing’s syndrome
What are the signs and symptoms of hypernatraemia?
Symptoms of hypernatremia are normally only seen when [Na] > 160mmol/L
Asymptomatic
Excessive thirst
Weakness
Lethargy
Irritability
Confusion
> 200 = ataxia, tremor, coma, seizures
How would investigate hypernatraemia?
Bloods = Na, glucose, K, Cl, urea, Cr
Blood gas = acid-base balance
Urine osmolality
ADH levels
CT head
How would you manage hypernatraemia?
Replace any fluid deficit = enteral water preferred
If not enteral = IV 5% dextrose (most preferred), 0.9% saline (used if evidence of volume depletion) or 0.45% saline, or Hartmann’s solution
Correct the serum Na at a suitable rate = risk of cerebral oedema (lower by 10mmol/L/day)
DI = desmopressin
What are the complications of hypernatraemia?
Confusion
Muscle twitching
Bleeding in or around the brain.
How would you assess a pts fluid balance?
BP (90/60 - concern)
• Kidney disease (electrolyte imbalance)
• Dehydration (dry mouth, sunken eyes)
• Urine output (1/2ml per kg per hour)
• Heart failure (overload = oedema)
• 3rd heart sound = early diastolic murmur (vol overload)
• 4th heart sound = auscultation in the ventricles
• Cap refill = normal is <2 secs
• Urea/creatinine = good measure of renal function
• Regular monitoring of pt weight (once a week)
• Hepatomegaly = vol overload
• Taut, non-pliable skin = interstitial fluid excess
What are the potential complications of rapid over-correction of high sodium levels?
Cerebral oedema = lower by 10mmol/L/day
