A 62-year-old woman is evaluated in the ambulatory clinic for a routine follow-up. She has… — USMLE Step 3

A $62$ -year-old woman is evaluated in the ambulatory clinic for a routine follow-up. She has a history of ischemic cardiomyopathy with a left ventricular ejection fraction of $30\%$ , type 2 diabetes mellitus, and osteoarthritis. She also reports a two-day history of dysuria and increased urinary frequency. Current medications include sacubitril-valsartan, metoprolol succinate, spironolactone, metformin, empagliflozin, and over-the-counter ibuprofen. Her blood pressure is $118/76$ mmHg and her pulse is $68$ /min. Physical examination shows $1+$ bilateral pitting edema of the lower extremities.

Laboratory studies from today show:
- Serum sodium: $137$ mEq/L
- Serum potassium: $5.3$ mEq/L
- Serum creatinine: $2.3$ mg/dL (Baseline $3$ months ago: $1.4$ mg/dL)
- Estimated GFR: $24$ mL/min/ $1.73$ m $^2$
- Urinalysis: Positive for leukocyte esterase and nitrites, $>50$ WBCs/hpf

Which of the following pharmacologic interventions are appropriate for this patient? (Select all that apply)

Advise discontinuation of over-the-counter ibuprofenAnswer
Discontinue metformin therapyAnswer
Discontinue spironolactone therapyAnswer
D
Increase the dose of sacubitril-valsartan
E
Initiate pioglitazone therapy for glycemic control
F
Prescribe trimethoprim-sulfamethoxazole for the urinary tract infection

Answer

The correct interventions are to advise the discontinuation of ibuprofen, discontinue metformin, and discontinue spironolactone.

The correct interventions involve discontinuing medications that are now toxic due to the patient's acute kidney injury and hyperkalemia. Ibuprofen must be stopped because NSAIDs cause afferent arteriolar vasoconstriction, worsening GFR and fluid retention. Metformin must be discontinued because its clearance is significantly reduced at an eGFR of

<30

mL/min/

1.73

^2

, leading to a high risk of lactic acidosis. Spironolactone must be discontinued because mineralocorticoid receptor antagonists are contraindicated in patients with an eGFR

<30

mL/min/

1.73

^2

or a serum potassium

>5.0

mEq/L.

Step-by-Step Solution

Analyze the patient's current clinical status and laboratory findings.

The patient has developed an acute kidney injury (creatinine increased from

1.4

2.3

mg/dL, eGFR dropped to

24

mL/min/

1.73

^2

) along with hyperkalemia (K

^+

5.3

mEq/L) and fluid overload.

Identifying the acute physiological derangements is necessary to guide medication reconciliation.

Evaluate current home medications against the new laboratory parameters.

Ibuprofen is nephrotoxic and exacerbates heart failure. Metformin is contraindicated at eGFR

<30

. Spironolactone is contraindicated with eGFR

<30

and potassium

>5.0

Preventing adverse drug events requires stopping medications that become unsafe during acute organ dysfunction.

Assess the proposed new interventions for safety and efficacy.

Increasing ARNI dosing is unsafe due to AKI/hyperkalemia. Pioglitazone is contraindicated in heart failure. Trimethoprim-sulfamethoxazole for the UTI is unsafe due to severe hyperkalemia risk.

New prescriptions must not worsen the patient's existing acute metabolic or hemodynamic derangements.

Key Concept

Comprehensive medication reconciliation in the setting of acute kidney injury and hyperkalemia requires discontinuing nephrotoxic agents (NSAIDs), holding medications contraindicated at low GFR thresholds (metformin), and avoiding drugs that exacerbate hyperkalemia (spironolactone, trimethoprim).

Estimated Time:2m 0s

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