Hypokalaemia Flashcards
1
Q
What is hypokalaemia?
A
Serum potassium < 3.5mmol/L
2
Q
What are the Sx of hypokalaemia?
A
- muscle weakness
- hypotonia
- hyporeflexia
- cramps
- tetany
- palpitations
- lightheadedness
- constipation
3
Q
What are the ECG changes of hypokalaemia?
A
- K < 3.0mmol/L
- flattening and inversion of T wave
- ST depression
- U wave
- severe
- QT prolongation
- Torsades de points
- Ventricular tachycardia
4
Q
What are the causes of hypokalaemia?
A
- Diuretics (thiazide, furosemide)
- V&D
- Pyloric stenosis
- Rectal villous adenoma
- Intestinal fistulas
- Cushing’s syndrome/steroids/ACTH
- Conn’s syndrome
- Alkalosis
- Alcohol abuse
- Renal tubular failure
5
Q
When would you suspect Conn’s?
A
- HTN
- Hypokalaemic alkalosis
- Not on diuretics
6
Q
How would you Mx hypokalaemia?
*think mild and severe
A
Mild-moderate(K > 2.5, no sx)
- Oral K supplements (40-120 mmol/day)
- Review K after 3 days
Severe
- IV K continuously, not not exceed 10 mmol/hour and not more con than 40mmol/L
*DO NOT GIVE K AS BOLUS - can cause arrythmias
7
Q
What are the classifications of Hypokalaemia?
A
- Mild - 3.1-3.5 mmol/L
- Moderate - 2.5-3.0 mmol/L
- Severe - <2.5 mmol/L
8
Q
What is the most common electrolyte abnormality affecting hospitalised patients?
A
- Hypokalaemia
9
Q
A
10
Q
What are the cx of hypokalaemia?
A
- Cardiac arrhythmias and sudden cardiac death
- Muscle weakness, flaccid paralysis, rhabdomyolysis.
- Abnormal renal function
- nephrogenic diabetes insipidus
- metabolic alkalosis
- enhanced renal chloride excretion.
- Iatrogenic hyperkalaemia
- Contributes to digoxin toxicity.
- Contributes to the development of hepatic encephalopathy in cirrhosis
11
Q
How does Thiazide and loop diuretics cause hypokalaemia?
A
- Thiazide blocks NCCT at DCT
- Furosemide blocks NKCC2 at TAL
- Both cause enhanced Na delivery to collecting duct
- This causes K loss at collecting duct through K channels
