Do I have chronic kidney disease (CKD) with a creatinine-based estimated glomerular filtration rate (eGFR) of 58.0, cystatin C-based eGFR of 70.0, and normal urine albumin-to-creatinine ratio (uACR)?

Do You Have CKD? Understanding Your Mixed eGFR Results

Based on your creatinine-based eGFR of 58 mL/min/1.73 m² without albuminuria, KDIGO guidelines recommend measuring cystatin C for confirmation—and since your cystatin C-based eGFR is >60 mL/min/1.73 m² (70.0), the diagnosis of CKD is NOT confirmed. 1

The KDIGO Confirmatory Testing Algorithm

The 2013 KDIGO guidelines established a specific protocol for your exact situation 1:

• When creatinine-based eGFR is 45-59 mL/min/1.73 m² AND you have no markers of kidney damage (normal uACR), cystatin C should be measured as a confirmatory test 1
• If cystatin C-based eGFR OR combined creatinine-cystatin C eGFR is >60 mL/min/1.73 m², the diagnosis of CKD is NOT confirmed 1
• If both remain <60 mL/min/1.73 m², then CKD would be confirmed 1

In your case, the cystatin C-based eGFR of 70 mL/min/1.73 m² is above the 60 threshold, which means you do not meet criteria for CKD according to this confirmatory testing approach 1.

Why the Discrepancy Exists

The difference between your creatinine-based (58) and cystatin C-based (70) eGFR is clinically significant and reflects important biological factors 1:

• Non-GFR determinants of creatinine include muscle mass, diet (particularly protein intake), certain medications, and body composition 1
• Your creatinine-based eGFR may be falsely low if you have reduced muscle mass, follow a vegetarian or low-protein diet, or have conditions affecting muscle metabolism 1
• The 2024 KDIGO guidelines explicitly state that cystatin C-based eGFR may be more appropriate when reduced muscle mass is the primary abnormality affecting creatinine 1

What This Means Clinically

You are in the "gray zone" where creatinine suggests mild kidney dysfunction but cystatin C does not confirm it 1:

• In a kidney transplant study applying this exact KDIGO strategy, 23% of patients with creatinine-based eGFR 45-60 and no albuminuria were incorrectly classified as having CKD when measured GFR was actually >60 1
• The combined creatinine-cystatin C equation (eGFRcreat-cys) provides the most accurate GFR estimation and should theoretically be used to resolve discrepancies 1
• Your cystatin C value of 1.04 mg/L is within normal range, supporting the higher eGFR estimate 1

Critical Diagnostic Requirement: Chronicity

Even if your eGFR were consistently <60, CKD requires abnormalities persisting for at least 3 months 2, 3:

• A single measurement is insufficient for diagnosis 2
• You need repeat testing in 2-4 weeks to 3 months to establish chronicity 3
• Without evidence of kidney damage (your uACR is normal) AND without confirmed low eGFR on cystatin C testing, you do not currently meet CKD diagnostic criteria 2

What You Should Do Next

Follow-up monitoring rather than CKD treatment is appropriate 1:

1. Repeat both creatinine and cystatin C measurements in 3 months to assess for stability or change 1, 3
2. Recheck uACR to confirm absence of albuminuria 3
3. Evaluate for factors affecting creatinine: Review your diet (protein intake), muscle mass, recent exercise, and medications that may affect creatinine secretion 1
4. Consider calculating the combined creatinine-cystatin C eGFR using the CKD-EPI 2021 equation for the most accurate assessment 1

Important Caveats

The discrepancy between your two eGFR values has prognostic significance even if CKD is not confirmed 4:

• Research shows that a large positive difference (eGFRcreat minus eGFRcys) is associated with higher cardiovascular risk and faster coronary artery calcification progression in patients with confirmed CKD 4
• However, this research was conducted in patients with established CKD, not in those where CKD diagnosis is uncertain 4
• Your situation (eGFRcreat 58, eGFRcys 70, difference of -12) actually shows the opposite pattern—cystatin C suggests better kidney function than creatinine 4

The Bottom Line

You do not currently meet diagnostic criteria for CKD because: (1) your confirmatory cystatin C-based eGFR is >60 mL/min/1.73 m², (2) you have no albuminuria or other markers of kidney damage, and (3) the KDIGO guidelines specifically state that CKD is "not confirmed" in this scenario 1. However, you should undergo repeat testing in 3 months to establish whether any abnormality is chronic and to determine your true baseline kidney function 1, 3.