HD is a 28 year old African American female with no known past medical history who comes to her regular primary care manager. Her vital signs taken reveal a blood pressure of 145/85. Upon repeat 15 minutes later after resting a similar result is found. She denies taking any recent use of decongestants and did not drink her coffee this morning. One week later she returns with similar blood pressure and a 6 week trial of lifestyle changes does not bring her to goal. The provider wishes to start hydrochlorothiazide 25mg once daily. Which of the following electrolytes should be monitored with chronic therapy? Select all that apply.
A. Serum sodium
B. Serum potassium
C. Serum magnesium
D. Urine sodium
E. Urine potassium
Answer with Rationale.
The correct answers are A, B, and C. Diuretics are used often for hypertension management as a first line agent. Go look at your pharmacy shelf and see how many agents combine one drug class with a thiazide. It is too numerous to count!
Thiazide diuretics can cause significant electrolyte abnormalities including hyponatremia, hypomagnesemia, hypokalemia, and hypercalcemia. Loop diuretics cause each of those as well except for calcium where they can cause hypocalcemia but are typically only used over thiazides in patients with significant kidney disease. Therefore having baseline electrolyte values and periodic monitoring of these is appropriate for patients receiving diuretic therapy. Urinary sodium or potassium would not be appropriate as it would be assumed that these levels would be higher than patients not on these medications.