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Creatinine-based eGFR limitation — ESENeph MCQ

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HardChronic Kidney DiseaseCreatinine-based eGFR limitationESENeph

A 58-year-old man has CKD G3a on creatinine-based eGFR during routine testing. He is a bodybuilder using creatine supplements; eGFRcr is 54 mL/min/1.73 m² on two samples. Urine ACR is 1.2 mg/mmol, urinalysis is negative and blood pressure is 122/74 mmHg. What is the most appropriate investigation?

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Correct answer: E — Check cystatin C-based eGFR to clarify kidney function

Creatinine-based eGFR can underestimate kidney function in people with high muscle mass or creatine use; cystatin C can help clarify whether CKD is truly present. There is no evidence of CKD-MBD, fluid overload or significant proteinuria. Renal biopsy is not justified by isolated creatinine-based eGFR in this context. The pearl is that CKD diagnosis should be interpreted alongside urine ACR, urinalysis, imaging and clinical context.

Reference: KDIGO 2024 CKD Guideline; NICE NG203