BOF: 9
A 56
year old male is reviewed in the hypertension clinic. His hypertension is well
controlled on bendroflumethiazide. Routine biochemistry shows his potassium
level to be 3.2 mmol /L
Which
of the following best describes the mechanism by which bendroflumethiazide
causes hypokalaemia?
a)
Increased filtration of potassium through the glomerulus
b)
Increased amounts of sodium reaching the distal tubules
c)
Direct action on potassium co-transporter
d)
Inhibition of the renin angiotensin aldosterone system
e)
Inhibition of anti diuretic hormone
Answer: b)
Bendroflumethiazide
ü
Inhibits active chloride reabsorption at the early distal tubule via the Na-Cl
co-transporter
ü
Increases excretion of sodium, chloride, and water
ü
Also inhibits sodium ion transport across the renal tubular epithelium through
binding to the thiazide sensitive sodium-chloride transporter
ü
Increases potassium excretion via the sodium-potassium exchange mechanism
