What is the chronic kidney disease (CKD) stage with a creatinine level of 1.10 and an estimated Glomerular Filtration Rate (GFR) of 43.1?

Chronic Kidney Disease Staging with Creatinine 1.10 and eGFR 43.1

A creatinine level of 1.10 and an estimated GFR of 43.1 mL/min/1.73 m² indicates Stage 3b Chronic Kidney Disease (CKD).

CKD Classification Based on GFR

CKD is defined as abnormalities of kidney structure or function present for more than 3 months with implications for health 1. The staging system is primarily based on estimated glomerular filtration rate (eGFR):

• Stage 1: Normal or increased GFR (≥90 mL/min/1.73 m²) with evidence of kidney damage 1
• Stage 2: Mildly decreased GFR (60-89 mL/min/1.73 m²) with evidence of kidney damage 1
• Stage 3a: Mild to moderate GFR decrease (45-59 mL/min/1.73 m²) 1
• Stage 3b: Moderate to severe GFR decrease (30-44 mL/min/1.73 m²) 1
• Stage 4: Severe GFR decrease (15-29 mL/min/1.73 m²) 1
• Stage 5: Kidney failure (<15 mL/min/1.73 m² or dialysis) 1

With an eGFR of 43.1 mL/min/1.73 m², this patient falls into Stage 3b CKD, which represents a moderate to severe decrease in kidney function 1.

Clinical Implications of Stage 3b CKD

Stage 3b CKD has significant clinical implications:

• Increased risk for progression to kidney failure 2
• Higher risk of cardiovascular disease, as CKD is considered a coronary heart disease risk equivalent 1
• Need for more frequent monitoring of kidney function 1
• Potential complications including anemia, bone mineral disorders, and electrolyte abnormalities 1

Relationship Between Serum Creatinine and eGFR

It's important to understand that serum creatinine alone is not sufficient for staging CKD:

• The same creatinine value can correspond to different eGFR values depending on age, sex, race, and body size 3
• For example, a creatinine of 1.10 mg/dL may represent different stages of CKD in different patients 3
• eGFR equations like the MDRD or CKD-EPI formulas account for these variables and provide more accurate assessment of kidney function 1, 4

Recommended Follow-up and Management

For patients with Stage 3b CKD:

• Regular monitoring of kidney function at least every 6 months 1
• Assessment for albuminuria to further stratify risk 1
• Evaluation and management of cardiovascular risk factors 1
• Blood pressure control, with ACEIs or ARBs preferred in patients with albuminuria 1
• Glycemic control in patients with diabetes 1
• Avoidance of nephrotoxic medications 1
• Consideration of referral to nephrology, especially if rapid progression or complications are present 5

Common Pitfalls in CKD Staging

Several important caveats should be considered:

• Single measurements of eGFR can be misleading; CKD diagnosis requires persistence of decreased eGFR for at least 3 months 1, 6
• eGFR values may fluctuate; approximately 40% of patients show variability in CKD stage over time 6
• Certain conditions like acute illness, high protein intake, or medications can temporarily affect creatinine levels and eGFR 1
• Alternative filtration markers like cystatin C may be considered when creatinine-based estimates are less reliable 7

Preparation for Potential Disease Progression

For patients with Stage 3b CKD:

• Education about kidney disease and its management should begin 5
• Monitoring for progression to Stage 4 (eGFR <30 mL/min/1.73 m²), at which point preparation for possible renal replacement therapy should be discussed 5
• Assessment for modifiable risk factors that could accelerate disease progression 1