Diuretic antihypertensives -- risk of dehydration/electrolyte imbalance?

My wife recently began taking a new antihypertensive drug, and this morning she asked a question that she had unaccountably forgotten to bring up with her doctor.

Since high blood pressure medications often function by increasing fluid removal via the kidneys, what are the implications for the risk of electrolyte imbalance? And what are the implications for the risk of dehydration?

I’m about to call the pharmacy to see what the pharmacist has to say about it. But any informed answers will also be appreciated.

P.S. Turns out her medication is an angiotensin II receptor antagonist, rather than a diuretic, so it doesn’t appear to apply to her. Still, it’s an interesting question, about diuretics.

Yes, electrolyte imbalances are one of the major possible side effects of diuretics. There are 7 major classes of drugs with diuretic properties: Osmotic diuretics (Mannitol), carbonic anhydrase inhibitors (Acetazolamide), Thiazide diuretics (Hydrochlorothiazide), Loop diuretics (Furosemide), Potassium-sparing (Spironolactone), Aquaretics (Conivaptan), and Natriuretic peptides (Nesiritide).

The main ones you need to monitor electrolyte imbalances with are Thiazides, Loops, and Potassium-sparing. Each could raise or lower such major electrolytes such as Potassium, Sodium, and Cloride.

Oh, and ACE-I, ARBs, Calcium Channel Blockers, and Beta Blockers don’t really effect electrolyte balances, so electrolyte levels are not normally monitored with these anti-hypertensives.

If you have a question about a particular class, I can elaborate if needed.

What’s the difference between Aquaretics and Osmotic diuretics, Hirka?

An Osmotic diuretic works by increasing the osmolarity in the proximal tubule and the descending loop of henle (in the nephrons of the kidney). As the osmolarity increases, the H2O follows in order to even out the osmolarity. This makes more water stay in the renal tubule and hence, more urine is produced.

Aquaretics on the other hand, work by inhibiting the action of Anti-Diuretic Hormone (ADH), also known as Vasopressin. This is the hormone that is released by the pituitary gland that controls how much you have to pee. When your body wants to retain water, the pituitary releases ADH, which causes more water to be reabsorbed in the collecting ducts. By inhibiting ADH, less water is reabsorbed, and you produce more urine.