hypernatraemia

Question 1

common causes of hypernatraemia

Answer 1

1. free water deficit - caused by excessive fluid loss through diarhhoea or vomiting, sweating, increased diuresis or insufficienct water intake
2. renal sodium overload due to high sodium intake eg. hypertonic infusion, drinking sea water or inadquately high sodium resorption by the kidneys

Question 2

symptoms of hypernatraemia

Answer 2

lethargy, confusion, focal neurological deficits, seizures, coma
signs of cellular dehydration eg. dry mucous membranes, decreased salivation

Question 3

hypovolaemic hypernatraemia

Answer 3

extrarenal cause will manifest with oliguria due to dehydration
- GI loss, dermal fluid loss, third space loss ie. periontitis, ascitis
renal cause (leads to dehydration due to polyuria)
- diuretics, osmotic diuresis, polyuric phase of tubular necrosis

Question 4

euvolaemic hypernatraemia

Answer 4

extrarenal - manifests withh oliguria due. to decreased water intake
renal - causes increased thirst due to polyuria

Question 5

hypervolaemic hypernatraemia

Answer 5

extrarenal causes - polyuria due to fluid overload, followed by dehration due to polyuria
renal - causes hypertension and hypokalaemia with normal urine output and no fluid overload

Question 6

symptoms of acute hypernatraemia

Answer 6

mild symtpoms: decreased salivation, dry mucous membranes
moderate symptoms: confusions, irritability, restlessness, lethargy, muscle weakness
severe symptoms: focal neurological deficits, seizures, coma

Question 7

approach

Answer 7

confirm hypernatraemia
ppatient history - low fluid iintake, diarhhoea
clinical assessment of volume status
urine osmolality and urine sodium concentration

Question 8

treatment of hypernatraemia

Answer 8

replacing free water deficit with sterile water enterally or 5% dextrose IV

Question 9

complications of hyponatraemia

Answer 9

intracranial heamorrhage - cell dehydration and shrinkage of brain tissue can cause intracranical vessels to rupture
heamorrhages may lead to irreversible neurological deficits
osmotic dymelination syndrome - demylinating brain lesions from acute rise in serum sodium levels and serum osmolality (more commonly seen in overcorrected of hyponatraemia)
rhabdomyalysis - severe hypernatraemia can damage the cell membranes of muscle cells

Question 10

hypperosmotic hyprglycaemic syndrome

Answer 10

results from diabetes
hyperglycaemia raises blood osmolality
pulls water out of cells and reduces serum sodium concentration
osmotic diuresis due to elevated serum osmolality in which water exceeds sodium loss and results in hypovolaemic hypernatraemia