Chronic kidney disease in the U.S.: eGFR stages and key interpretations

A lab result landed in my inbox, and—like it always does—the eGFR line made me pause. I’ve learned that this one number is powerful, but it is not a verdict on its own. I wanted to write down what I now look for when I see eGFR and how I think about the stages of chronic kidney disease (CKD) in everyday life, especially in a U.S. context where millions live with CKD, many without realizing it. If you’re reading your results at the kitchen table the way I do—half curious, half anxious—this is my calm, practical guide to making sense of it without jumping to conclusions.

The lab number that made me stop and think

At first, eGFR felt like a pass/fail grade. Then it clicked: eGFR is an estimate of filtering function, not an exact ruler. It’s calculated from blood creatinine (sometimes cystatin C), age, and sex, and most U.S. labs now use the 2021 race-free equation. The most useful early lesson for me was this: a single eGFR value rarely tells the whole story. I ask myself three things right away—is this new or persistent (over 3+ months), are there other signs of kidney damage like albumin in the urine, and does anything else explain a temporary dip such as dehydration, a new medication, or an acute illness. For background overviews, I like the patient pages at NIDDK and the surveillance snapshots from the CDC.

• High-value takeaway: CKD is defined by abnormal kidney findings for at least 3 months—not by one off-day lab.
• Context matters: muscle mass, hydration, and recent illness can nudge creatinine (and therefore eGFR) up or down for a short time.
• Confidence grows with repeat testing and with a second marker (like urine albumin or cystatin C) when results are borderline.

eGFR in plain language

Glomerular filtration rate (GFR) is how much blood the kidneys filter each minute. Because directly measuring GFR is complex, labs estimate it (eGFR). In general, higher eGFR means better filtering. But because it’s an estimate built from other lab values, small shifts are common and do not necessarily mean progression. A steady trend over time tells a more reliable story than any single point. If a result surprises me, I note my hydration, recent workouts, or a new prescription (like an ACE inhibitor, ARB, or SGLT2 inhibitor) and compare with prior values before drawing conclusions. For thoughtful clinician guidance, the KDIGO CKD guideline is my go-to reference.

The stages at a glance

CKD stages are grouped by eGFR categories (G1–G5). Here is the widely used framework that helps me get oriented—remembering that G1 and G2 are only “CKD” if there’s other evidence of damage present (for example, albumin in the urine or structural changes on imaging):

• G1 — eGFR ≥90 mL/min/1.73m² (normal or high) with evidence of kidney damage
• G2 — eGFR 60–89 (mildly decreased) with evidence of kidney damage
• G3a — eGFR 45–59 (mild to moderate decrease)
• G3b — eGFR 30–44 (moderate to severe decrease)
• G4 — eGFR 15–29 (severely decreased)
• G5 — eGFR <15 (kidney failure range)

When I map my eGFR into one of these categories, I don’t stop there. I pair it with albumin in the urine (the UACR test), because that combination is what really sets the risk picture.

Why albumin in urine changes the story

Urine albumin-to-creatinine ratio (UACR) is a quiet superstar. It detects tiny protein leaks that the eye can’t see. The categories are straightforward:

• A1 — UACR <30 mg/g (normal to mildly increased)
• A2 — UACR 30–300 mg/g (moderately increased)
• A3 — UACR >300 mg/g (severely increased)

The G–A grid (eGFR category plus albuminuria category) is how many clinicians estimate risk and plan follow-up. For example, someone with G3a and A1 might need gentle monitoring and attention to blood pressure and cardiovascular health, while someone at G2 with A3 (higher albumin leak) may warrant closer follow-up despite a “decent” eGFR. The National Kidney Foundation has accessible explanations for patients—see their eGFR and albuminuria pages at the NKF.

Confirming before labeling CKD

CKD is about persistence. If my eGFR is below 60 once, I don’t self-label. I’d plan a repeat in a few weeks to months (timing depends on how low it is and whether I’m sick), and check UACR. If it’s borderline—say, eGFR 45–59 with no albuminuria—guidelines support confirmatory testing with cystatin C (eGFRcr–cys) when available, to reduce misclassification. For suspected long-standing disease, prior labs or an ultrasound can add clues. For suspected short-term injury (like after a stomach bug, a contrast study, or new NSAID use), it may fit acute kidney injury rather than CKD, which changes next steps. The NIDDK clinician tools explain these distinctions clearly.

What small swings may or may not mean

Analytic and biological variation mean a modest change (for example, a few mL/min/1.73m²) can happen even when kidney function is stable. I keep an eye on the trend, not just the latest dot. I also note things that can nudge creatinine temporarily:

• Hydration status, especially after heavy exercise or illness
• High meat intake right before a blood draw
• Certain medications (e.g., temporary creatinine bumps after starting an ACE inhibitor)
• Lab-to-lab differences or timing of the test during recovery from an acute event

If an unexpected low value appears, I’d consider rechecking under steadier conditions and adding urine albumin to complete the picture.

The U.S. view that grounds my decisions

CKD is common in the U.S.; diabetes, high blood pressure, and cardiovascular disease are frequent travel companions. That means conversations about blood pressure targets, glucose management, smoking cessation, and heart protection often matter as much as the kidney numbers themselves. I also think in terms of medicines and doses—many drugs are renally cleared, and dosing should respect the current eGFR category to avoid side effects. When in doubt, I look for drug dosing tables tied to eGFR ranges and ask my clinician or pharmacist to sanity-check a new prescription. The CDC’s CKD pages have practical prevention notes and patient-friendly graphics.

When I call in a pro sooner rather than later

There are times when I’d want a nephrology (kidney specialist) consult on the calendar instead of “wait and watch.” A few examples I keep handy (these are general patterns rather than absolute rules):

• eGFR <30 (G4 or lower) or a sustained rapid decline in eGFR
• Persistent A3 albuminuria or a sudden spike in albumin without a clear trigger
• Blood and protein in the urine together, or suspected inherited conditions
• Resistant hypertension, electrolyte imbalances that recur, or unexplained anemia
• Planning for pregnancy with known CKD, or complex medication decisions

Specialists can also help align blood pressure, diabetes, and cardiovascular plans with kidney-friendly strategies. For a guideline anchor, the KDIGO 2024 CKD guideline summarizes referral considerations and shared decision-making points.

My personal checklist for steady follow-up

To keep things grounded, I track three streams side by side—kidneys, heart, and daily habits. This is my simple, non-perfect system:

• Labs and vitals — eGFR, UACR, blood pressure log, A1C (if relevant), lipids. I write the date, not just the number.
• Medications — current dose, kidney adjustments discussed, any side effects, and who I asked for dosing advice.
• Context notes — illness, travel, heavy workouts, dehydration, big dietary shifts, or new supplements.

When I return to results months later, those notes are gold. They turn isolated numbers into a narrative that makes sense.

Small habits that felt surprisingly doable

Nothing here is a guarantee, but these patterns have made my conversations clearer and my days calmer:

• Choosing water first and pacing fluids through the day, especially during heat waves or after exercise
• Asking before I start or continue NSAIDs if my eGFR is reduced or albumin is elevated
• Scanning drug labels and handouts for “kidney” or “renal” sections and jotting questions
• Keeping blood pressure checks boringly routine and bringing the log to appointments
• Using plain-language patient pages like MedlinePlus when I need a refresher

Signals that tell me to slow down and double-check

Here are the red and amber flags I treat with extra respect. If any show up, I’d seek timely medical advice instead of self-managing:

• eGFR drifting downward over several tests, not explained by a recent illness
• New swelling in legs or around the eyes, shortness of breath, or dramatic changes in urine output
• Foamy urine or persistent dark/bloody urine
• Frequent high blood pressure readings despite taking medications as prescribed
• Confusion, chest pain, or severe weakness—emergency care may be needed

Even then, I remind myself: interpretation is collaborative. Clear notes and questions help clinicians help me.

What I’m keeping and what I’m letting go

I’m keeping the idea that CKD risk lives in the combo—eGFR plus albuminuria—rather than a single lonely number. I’m keeping the habit of confirming before labeling and asking about cystatin C when the story feels borderline. I’m also keeping the mindset that kidney health is heart health: blood pressure, glucose, and lifestyle choices share one big table.

I’m letting go of the impulse to catastrophize or to chase every small swing. I’m letting go of the myth that “once a number dips, there’s nothing to do.” There is usually plenty to do—clarify, confirm, and coordinate. And I’m letting go of the idea that I have to memorize it all. That’s what checklists and credible references are for.

FAQ

1) Does one low eGFR mean I have CKD?
No. CKD is about persistence (3+ months) or other evidence of damage like albumin in the urine. A repeat test and UACR help clarify the picture.

2) What’s the difference between G3a and G3b?
They’re both “stage 3,” but G3a is eGFR 45–59 and G3b is 30–44. G3b generally carries higher risk and may change medication dosing or follow-up plans.

3) My eGFR is 65. Is that CKD?
Not by itself. G2 (60–89) counts as CKD only if there’s other evidence of kidney damage (for example, elevated urine albumin) or structural abnormalities.

4) Should I ask for cystatin C?
It can be helpful when creatinine-based eGFR seems borderline or inconsistent with the big-picture clinical story. Many guidelines support confirmatory testing when available.

5) When should I see a nephrologist?
Typical triggers include eGFR <30, persistent A3 albuminuria, rapid decline, or complex issues like resistant hypertension or suspected inherited disease. Your primary clinician can help tailor the timing.

Sources & References

• KDIGO 2024 CKD Guideline
• NIDDK Kidney Disease Overview
• CDC Chronic Kidney Disease
• NKF Understanding eGFR
• MedlinePlus Kidney Diseases

This blog is a personal journal and for general information only. It is not a substitute for professional medical advice, diagnosis, or treatment, and it does not create a doctor–patient relationship. Always seek the advice of a licensed clinician for questions about your health. If you may be experiencing an emergency, call your local emergency number immediately (e.g., 911 [US], 119).