Kidney Talk by Shalini Mundra

Question: How much of an increase in serum creatinine is acceptable in patients who are started on angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs)?

ACEIs and ARBS are important drugs in the treatment of patients with chronic kidney disease. In proteinuric CKD, these drugs are used not only for blood pressure control (JNC VII) but also for reducing proteinuria. They are also the drug of choice to slow down the progression of proteinuric CKD.

Initiation (or dose increase) of ACEIs and ARBs may cause an increase in serum creatinine in some patients. A 20-30% increase in serum creatinine within 1-2 weeks is generally acceptable, as long it stabilizes. This may even be a good thing as indicated by a study by Bakris and Weir, where they reviewed 12 clinical trials, and found that an acute increase in serum creatinine of up to 30% was strongly associated with long-term preservation of renal function.

If the serum creatinine concentration rises by more than 30%, one should stop or reduce the dose and consider whether the patient has a high-renin state such as hypovolemia or uncompensated heart failure. ACEIs should be given a second trial if there is a reversible state like hypovolemia. Another potential cause of elevated serum creatinine levels could also be bilateral renal artery stenosis which should be considered in patients who are smokers or have extensive atherosclerotic cardiovascular disease.

Also these drugs may sometimes increase the serum potassium levels. A potassium level of up to 5.5 mEq/L is generally considered safe as long as it is stable and the patient is following a potassium restricted diet and is not taking any medications which can excacerbate hyperkalemia like NSAIDs and aldosterone antagonists. Diuretics can be used to promote potassium excretion.

Bottomline:

1. Serum creatinine and potassium should be checked within a week of starting ACEIs or ARBS and then should be monitored frequently.

2. A rise of 20-30% in serum creatinine is acceptable as long as it is stable.