Understanding CKD Staging: What Does a Creatinine Level of 105 µmol/L Really Mean?

When evaluating kidney health, healthcare professionals rely far more on the estimated Glomerular Filtration Rate (eGFR) than on serum creatinine alone. While creatinine is a widely used biomarker for kidney function, it's inherently limited—it reflects muscle mass, age, sex, body size, hydration status, dietary protein intake, and even certain medications. That means two people with identical creatinine levels may have vastly different kidney function.

Why Creatinine Alone Isn't Enough for CKD Staging

A serum creatinine value of 105 µmol/L falls just above the typical reference range for many healthy adults—especially younger men—but that doesn't automatically signal kidney disease. For example, a muscular 28-year-old male athlete might naturally have higher baseline creatinine due to greater lean muscle mass, while his eGFR could remain well above 90 mL/min/1.73m²—placing him firmly in Stage 1 CKD (normal or high GFR with evidence of kidney damage), or even outside CKD classification entirely.

The Gold Standard: eGFR-Based CKD Classification

The internationally accepted CKD staging system (KDIGO 2012 guidelines) defines five stages based primarily on eGFR—and secondarily on markers of kidney damage (e.g., albuminuria, structural abnormalities, or imaging findings). Here's how it breaks down:

CKD Stages at a Glance:

• Stage 1: eGFR ≥90 mL/min/1.73m² + kidney damage (e.g., persistent proteinuria or imaging evidence)
• Stage 2: eGFR 60–89 mL/min/1.73m² + kidney damage
• Stage 3a: eGFR 45–59 mL/min/1.73m²
• Stage 3b: eGFR 30–44 mL/min/1.73m²
• Stage 4: eGFR 15–29 mL/min/1.73m²
• Stage 5: eGFR <15 mL/min/1.73m² (or dialysis-dependent)

Crucially, a creatinine level of 105 µmol/L could correspond to an eGFR anywhere from >90 (Stage 1 or non-CKD) to <60 (Stage 3), depending on the individual's age, race, sex, and body composition. That's why clinicians always calculate eGFR using validated equations like the CKD-EPI creatinine equation.

Acute vs. Chronic: Context Is Everything

Another critical distinction is whether elevated creatinine reflects an acute kidney injury (AKI) or long-standing chronic kidney disease. A sudden rise to 105 µmol/L in someone previously stable may indicate dehydration, infection, NSAID use, or contrast dye exposure—all potentially reversible causes. In contrast, a gradual, sustained increase over months or years suggests progressive CKD and warrants comprehensive evaluation—including urine albumin-to-creatinine ratio (UACR), renal ultrasound, and blood pressure assessment.

If you've recently received a creatinine result of 105 µmol/L, don't panic—but do follow up with your provider for an eGFR calculation, urinalysis, and clinical context review. Early detection, lifestyle optimization (e.g., blood pressure control, low-sodium diet, diabetes management), and appropriate monitoring can significantly slow progression—even at early stages.