Hyponatremia and Hypernatremia (chemical pathology) Flashcards
What is the normal range of sodium ECF concentration?
135-145 mmol/L
What are the symptoms of hyponatremia?(4)
Weakness, dizziness, confusion and coma.
What are the signs of hyponatremia? (6)
- Oliguria, tachycardia, weight loss, peripheral circulatory failure, hypotension, decreased skin turgor.
Symptoms of acute hyponatremia.
Severe cerebral oedema, coma, seizures and respiratory distress.
True or false:
Chronic hyponatremia is a medical emergency.
False, it is acute hyponatremia that is a medical emergency.
What are the symptoms of chronic hyponatremia (5)
Headache, restlessness, muscle cramps, vomiting, lethargy.
What are the three causes of hyponatremia and their examples?
Decreased ECF volume-Thiazide diuretics, addison’s disease.
Increased ECF volume- Cirrhosis, impaired renal water excretion, heart failure.
Normal ECF volume- SIADH, hypothyroidism, Excessive water intake, psychogenic polydipsia.
Three circumstances in which hyponatremia can occur
- Sodium depletion (Hypovolemic hyponatremia)
-Water excess, sodium normal (euvolemic hyponatremia)
-Both water and sodium excess- Hypervolemic hyponatremia
How do we calculate osmolal GAP
Osmolal GAP = Osmolality - Osmolarity
Three things a clinician should do when assessing a patient with hypoNa
- History- time frame to development of hyponatremia.
-Establish fluid status (water retention/fluid loss) - Establish true hyponatremia
What is true hyponatremia?
Hypotonic hyponatremia
What causes isotonic hyponatremia? (2)
- Hyperlipidemia
Hyperproteinemia
What causes hypertonic hyponatremia? (2)
Hyperglycemia
Mannitol
What’s the next step to take in case of a hypotonic hyponatremia?
Assess volume status
What can be the causes of hypovolaemic hypotonic hyponatraemia ? (7)
Renal losses (urine sodium is high >40)
-Addison’s disease
-Diuretics
-Osmotic diuretics
Ketonuria
Extra-renal losses
-Diarrhoea
-Burns
-3rd space losses