Can a healthcare provider be acting in a patient's best interest by diagnosing Chronic Kidney Disease (CKD) with a slightly elevated estimated Glomerular Filtration Rate (eGFR) of 64 mL/min/1.73 m², despite not meeting the technical criteria for stage 3a CKD?

Diagnosing CKD with an eGFR of 64 mL/min/1.73 m²: The Provider Was Not Acting in the Patient's Best Interest

No, the provider was not acting in the patient's best interest by diagnosing CKD with an eGFR of 64 mL/min/1.73 m², as this value does not meet the technical criteria for CKD and such a diagnosis could lead to inappropriate labeling, unnecessary interventions, and potential harm. 1, 2

Why This Diagnosis Is Incorrect

The Diagnostic Criteria Are Clear and Specific

An eGFR of 64 mL/min/1.73 m² falls within Stage 2 CKD range (60-89 mL/min/1.73 m²), not Stage 3a (45-59 mL/min/1.73 m²). 1, 2 The cutoff of 60 mL/min/1.73 m² is not arbitrary in this context—it represents the threshold below which eGFR alone is sufficient to diagnose CKD. 1

For an eGFR between 60-89 mL/min/1.73 m², CKD diagnosis requires documented evidence of kidney damage (such as albuminuria, hematuria, pathological abnormalities on biopsy, or history of kidney transplantation) present for at least 3 months. 1, 2 Without these markers, a diagnosis of CKD cannot be made regardless of how "close" the eGFR is to 60. 2

The Temporal Component Is Essential

CKD diagnosis requires abnormalities present on at least two occasions over three months or longer. 2, 3 A single measurement of 64 mL/min/1.73 m² does not confirm CKD at any stage. 2 This temporal requirement exists precisely to avoid misdiagnosis based on transient changes in kidney function.

The Real Issue: Measurement Accuracy, Not Arbitrary Cutoffs

Creatinine-Based eGFR May Be Inaccurate

The provider's concern about cutoff points being "arbitrary" misses the actual clinical problem. The method used to estimate GFR matters significantly—creatinine-based equations may not accurately reflect true kidney function in individuals with variable muscle mass, malnutrition, or extreme body composition. 2

Research demonstrates that approximately 23% of patients with creatinine-based eGFR 45-59 mL/min/1.73 m² actually have normal kidney function (>60 mL/min/1.73 m²) when confirmed with measured GFR. 4

The Correct Approach: Confirmatory Testing

If there is genuine concern about kidney function in a patient with borderline eGFR values, KDIGO guidelines recommend measuring cystatin C in adults with eGFRcreat 45-59 mL/min/1.73 m² who lack other markers of kidney damage. 4, 1, 5

• If eGFRcys or the combined eGFRcreat-cys is also <60 mL/min/1.73 m², the diagnosis of CKD is confirmed. 4
• If eGFRcys or eGFRcreat-cys is ≥60 mL/min/1.73 m², the diagnosis of CKD is not confirmed. 4, 5

The combined creatinine-cystatin C equation provides 94.9% accuracy within 30% of measured GFR and should be the definitive value used for clinical decision-making when discordance exists. 1

Why "Close Enough" Is Harmful

Consequences of Inappropriate Diagnosis

Labeling a patient with CKD when they do not meet diagnostic criteria can lead to:

• Psychological burden and anxiety from being diagnosed with a chronic, progressive disease 4
• Inappropriate medication adjustments or withholding of beneficial therapies 5
• Unnecessary specialist referrals and healthcare costs 4
• Insurance and employment implications 4

The debate about CKD staging thresholds in the literature specifically addresses concerns about overdiagnosis, particularly in elderly individuals and women who may have age-appropriate reductions in GFR without true kidney disease. 4, 6

The Evidence Against Flexible Interpretation

Studies examining CKD diagnosis demonstrate that using a single screening test overestimates the proportion of people with CKD by approximately 25% compared to using two tests as recommended. 7 This underscores why adhering to diagnostic criteria—including the temporal component and the need for confirmatory evidence—is essential.

The Correct Clinical Algorithm

When encountering an eGFR of 64 mL/min/1.73 m² without evidence of kidney damage:

1. Do not diagnose CKD, as the patient does not meet criteria 1, 2
2. Assess for markers of kidney damage (albuminuria, hematuria, imaging abnormalities) 1, 2
3. If no kidney damage is present, repeat eGFR in 3 months to assess stability 2, 7
4. If there is clinical concern about the accuracy of creatinine-based eGFR (due to muscle mass, diet, or other factors), measure cystatin C and calculate eGFRcreat-cys 1, 5, 2
5. Only diagnose CKD if persistent abnormalities are documented over ≥3 months 2, 3

Common Pitfalls to Avoid

Do not conflate "being cautious" with making a premature diagnosis. The appropriate cautious approach is close monitoring and confirmatory testing, not diagnostic labeling without meeting criteria. 2

Do not assume that cutoff values are arbitrary simply because they are numerical thresholds. The 60 mL/min/1.73 m² threshold is based on extensive epidemiological data linking values below this level with adverse outcomes. 4

Do not ignore the requirement for temporal persistence. A single abnormal value does not constitute CKD regardless of the eGFR level. 2, 7