From the Guidelines
The patient should be advised to stop taking metformin (option D). Metformin is contraindicated in patients with significantly impaired kidney function, particularly when the glomerular filtration rate (GFR) falls below 30 mL/min/1.73 m², as stated in the 2022 KDIGO clinical practice guideline for diabetes management in chronic kidney disease 1. This patient's current GFR is 29 mL/min/1.73 m², which falls below this threshold. Metformin can accumulate in patients with reduced kidney function, increasing the risk of lactic acidosis, a rare but potentially fatal complication. The patient's situation is particularly concerning because she has both chronic kidney disease and a recent acute-on-chronic kidney injury from her pneumonia hospitalization. Her elevated creatinine level of 2.30 mg/dL (well above the reference range of 0.45-0.75 mg/dL) further confirms significant kidney impairment.
According to the guideline, when the eGFR is less than 30 mL/min/1.73 m², metformin should be stopped, as indicated in the table provided in the guideline 1. The other medications on her discharge list (amlodipine, atorvastatin, cefuroxime, and metoprolol) do not have the same level of risk in kidney disease and can generally be continued with appropriate monitoring or dose adjustments if needed.
Key points to consider:
- Metformin is contraindicated in patients with a GFR below 30 mL/min/1.73 m² 1
- The patient's current GFR is 29 mL/min/1.73 m², which falls below the recommended threshold
- Metformin can increase the risk of lactic acidosis in patients with reduced kidney function 1
- The patient's kidney function should be monitored regularly, and the dose of metformin should be adjusted accordingly 1
From the Research
Medication Review
The patient's discharge medications include atorvastatin, cefuroxime, amlodipine, extended-release metformin, and extended-release metoprolol succinate. Given the patient's stage 3 chronic kidney disease with a glomerular filtration rate of 29 mL/min/1.73 m', the medication that should be advised to stop taking is:
- Metformin
Rationale
The decision to stop metformin is based on the patient's severe renal impairment, as evidenced by a glomerular filtration rate of 29 mL/min/1.73 m' 2, 3, 4, 5. According to the studies, metformin should be discontinued if renal function falls below an estimated glomerular filtration rate of 30 mL/min/1.73 m' due to the increased risk of lactic acidosis and all-cause mortality 2, 5.
Key Findings
- Metformin is generally recommended to be discontinued in patients with severe renal impairment (eGFR < 30 mL/min/1.73 m') 2, 5
- The risk of lactic acidosis associated with metformin use in individuals with impaired kidney function is low, but increases in patients with severe renal impairment 3, 4, 5
- Metformin may be prescribed cautiously in patients with mild to moderate chronic kidney disease, with appropriate dosage reductions and careful follow-up of kidney function 3, 6