實戰課題Medical internship topic 6: Hyponatremia

Hyponatremia

1.      Def: <135mmol/L

2.      First DDx: rule out pseudo-hyponatremia

• Hypertonic: hyperglycemia?

Na在hyperglycemia時會降低，correct Na=Na + 1.4×(sugar－100)

• Isotonic : hyperlipidemia, hyperproteinemia?
• Another consideration: sample mixed with IV injection fluids?

3.      Hypotonic :

• Too much water? (beware of fluid retention)à do not give N/S, but restrict Na+ and water intake
• Not enough solutes? (beware of poor intake)à may give N/S

4.      Symptoms:

nausea and vomiting, headache, confusion, loss of energy and fatigue,

restlessness and irritability, muscle weakness, spasms or cramps, seizures, coma

5. Na supplement if needed

•  Rate of infusion is important
•  應補鈉總量（mmol）=[135-病人血Na+(mmol/L)]×體重(kg)×0.6~0.5
•  補鈉的速度不能超過4~6 mEq/L/hour，24 hrs內不能超過9 Eq/L

6. Monitoring

•   Urine output
•   Na recheck Q4H