What medication needs adjustment in a 74-year-old patient with Hypertension (HTN), Paroxysmal Atrial Fibrillation (pAF), Stage 2 Chronic Kidney Disease (CKD) and back pain on losartan, eliquis (apixaban), metoprolol and morphine (morphine) with Impaired Renal Function, as indicated by a rise in serum creatinine (sCR) from 1.5 to 2.1?

Losartan Should Be Temporarily Discontinued Due to Acute Kidney Injury

In a 74-year-old patient with HTN, pAF, Stage 2 CKD, and back pain showing a rise in serum creatinine from 1.5 to 2.1 mg/dL, losartan should be temporarily discontinued as it is the most likely cause of the acute kidney injury.

Assessment of the Creatinine Rise

The patient's serum creatinine has increased by 0.6 mg/dL (40% increase), which meets criteria for Acute Kidney Injury (AKI) according to KDIGO guidelines 1:

• An increase in serum creatinine by ≥0.3 mg/dL within 48 hours, or
• An increase to ≥1.5 times baseline within 7 days

This significant rise requires immediate attention as it indicates substantial deterioration in renal function.

Medication Analysis

Let's analyze each medication the patient is taking:

1. Losartan (ACE inhibitor/ARB):

   • Most likely culprit for the creatinine elevation
   • ACE inhibitors and ARBs can cause a rise in serum creatinine by reducing efferent arteriolar tone, decreasing glomerular filtration pressure 1
   • Guidelines recommend considering dose reduction or discontinuation when creatinine rises >30% from baseline 1

2. Eliquis (apixaban):

   • Dose adjustment may be needed with declining renal function
   • However, not the primary cause of the acute creatinine rise
   • FDA labeling indicates dose adjustment when creatinine is ≥1.5 mg/dL with age ≥80 or weight ≤60 kg 2

3. Metoprolol:

   • Generally well-tolerated in renal impairment
   • Not typically associated with acute kidney injury
   • No immediate adjustment needed

4. Morphine:

   • Metabolites can accumulate in renal impairment
   • May need dose adjustment but not the primary cause of the acute rise

Management Approach

1. Immediate action:

   • Temporarily discontinue losartan
   • The American Heart Association recommends discontinuation of ACE inhibitors/ARBs when serum creatinine rises >30% above baseline 1

2. Monitoring:

   • Recheck renal function within 3-7 days after discontinuing losartan
   • Monitor blood pressure closely during this period

3. After stabilization:

   • If creatinine improves, consider restarting losartan at a lower dose
   • If patient has proteinuria or diabetic nephropathy, the renoprotective effects of losartan may outweigh risks 3

Rationale for Focusing on Losartan

The rise in creatinine is most consistent with ACE inhibitor/ARB-induced AKI because:

1. The magnitude of rise (40%) exceeds the threshold of concern (30%) mentioned in guidelines 1

2. ARBs like losartan can cause an initial decline in GFR that is more pronounced in patients with pre-existing kidney disease 4

3. Other potential causes (volume depletion, NSAID use) should be investigated, but losartan remains the most likely culprit given the medication list 1

Important Considerations

• While temporary discontinuation is recommended, long-term ARB therapy provides significant renoprotective benefits in patients with CKD 3

• After stabilization, if losartan is restarted, close monitoring of renal function is essential

• The patient's other medications (apixaban, metoprolol, morphine) may need dose adjustments based on the new level of renal function, but they are not the primary targets for immediate intervention

• Ensure the patient is adequately hydrated, as volume depletion can exacerbate ARB-induced renal dysfunction 1