Discontinuing ibuprofen is an appropriate next step in managing this patient's blood pressure. She has elevated blood pressure not yet defined as hypertension, a diagnosis that requires a systolic blood pressure ≥140 mm Hg and/or a diastolic blood pressure ≥90 mm Hg documented during three separate office visits over a period of 1 week or longer. In this case, a review of medications, including over-the-counter and herbal medications, is important because a number of these agents can contribute to elevated blood pressure. This patient is taking an NSAID, ibuprofen, for osteoarthritis. All NSAIDs contribute to hypertension by inhibition of cyclooxygenase-2 in the kidneys, promoting sodium retention and increased intravascular volume. Additional effects of NSAIDs include hyperkalemia, which is mild in this case. NSAIDs lower renal renin secretion and angiotensin II–induced aldosterone release, reducing urine potassium excretion. Therefore, discontinuing the ibuprofen is appropriate for this patient. Reassessing her blood pressure when not taking an NSAID will provide a more accurate measure of her baseline blood pressure status.

Beginning antihypertensive therapy at this point is not indicated; in particular, ACE inhibitor use would be contraindicated because further inhibition of the renin-angiotensin system could exacerbate this patient's hyperkalemia.

Similarly, hydrochlorothiazide is an effective antihypertensive agent, but initiating treatment is not indicated prior to establishing a diagnosis of hypertension.

A plasma aldosterone-plasma renin ratio is used to evaluate patients with hypertension and a high suspicion for hyperaldosteronism (for example, evidence of resistant hypertension and a low serum potassium level). Testing is therefore not indicated in this patient without a clear diagnosis of hypertension and who has hyperkalemia.