# CKD Diagnosis and Staging: Cause, GFR, Albuminuria

Document cause + G category + A category, then use trajectory and validated risk to decide monitoring, referral, and preparation.

![Infographic: CKD Diagnosis and Staging: Cause, GFR, Albuminuria](https://urinenephrology.org/visual-reference/images/student-ckd-staging.png?v=20261003c)

## Confirm at least 3 months

CKD means persistent kidney damage or eGFR below 60 mL/min/1.73 m² for ≥3 months. Look for previous results, albuminuria, sediment or structural abnormalities. A new abnormal value during illness may be AKI; investigate now rather than simply waiting 3 months.

## Assign the G category

G1 ≥90; G2 60–89; G3a 45–59; G3b 30–44; G4 15–29; G5 <15 mL/min/1.73 m². G1/G2 alone do not establish CKD without a damage marker. Record the cause separately; stage does not diagnose the disease.

## Add the A category

Use urine albumin:creatinine ratio: A1 <30, A2 30–300, A3 >300 mg/g. Confirm an unexpected positive result, preferably with a first-morning specimen. Fever, exercise, infection, and menstruation can transiently increase albumin or contaminate the sample.

## Explain the combination

Synthetic example: persistent eGFR 52 and UACR 450 is G3a A3, not mild disease simply because filtration exceeds 45. Albuminuria increases kidney and cardiovascular risk and can change eligibility for protective treatment.

## Connect prediction to a service

For eligible CKD G3–G5, validated kidney-failure risk can support referral: 5-year risk 3–5% for nephrology; 2-year >10% for multidisciplinary care; >40% for modality education and preparation. These supplement eGFR, symptoms, cause, and trajectory.

## Recheck what changes management

Assess eGFR and albuminuria at least annually, more often at higher risk or after treatment changes. An eGFR change >20% or ACR doubling exceeds expected variability and merits evaluation. Use combined creatinine–cystatin C estimation when accuracy will change a decision.

## Supporting evidence

- [Supporting guideline or source](https://kdigo.org/wp-content/uploads/2026/04/KDIGO-2024-CKD-Guideline.pdf)

## Source lessons

- [chapter 09 ckd](https://urinenephrology.org/nephrology-textbook/chapters/chapter-09-ckd.html)
- [ckd complications student handout](https://urinenephrology.org/student-resources/ckd/ckd-complications-student-handout.html)
- [ckd comprehensive management pathways](https://urinenephrology.org/student-resources/ckd/ckd-comprehensive-management-pathways.html)
- [ckd overview student handout](https://urinenephrology.org/student-resources/ckd/ckd-overview-student-handout.html)
- [ckd staging student handout](https://urinenephrology.org/student-resources/ckd/ckd-staging-student-handout.html)

Read alongside the full lessons; the findings and decisions shown here require the stated clinical context.