KDIGO Guidelines — How to Assess Proteinuria
KDIGO Guidelines — How to Assess Proteinuria (2024 Update)
KDIGO recommends initial testing and confirmation using albuminuria or total protein measurements with standardized, reproducible methods.
✅ 1. First-line test
Spot urine Albumin-to-Creatinine Ratio (ACR)
- Preferred initial test for detecting proteinuria in adults.
- Performed on a first-morning void when possible (reduces variability).
- Reported as mg/g or mg/mmol.
✅ 2. Acceptable alternatives (if ACR not available)
- Protein-to-Creatinine Ratio (PCR) on spot urine.
- Semi-quantitative dipstick testing only for screening, not for diagnosis.
✅ 3. When to confirm abnormalities
If initial ACR/PCR is elevated:
- Repeat ACR on first-morning urine to confirm persistent albuminuria.
- KDIGO requires ≥2 of 3 samples positive over 3 months to diagnose chronic albuminuria.
✅ 4. When 24-hour urine is recommended
24-hour urine protein NOT routinely required, but may be indicated when:
- Precise quantification is essential (e.g., nephrotic syndrome).
- Spot ACR/PCR is unreliable (e.g., extremes of muscle mass).
- Suspected non-albumin predominant proteinuria (e.g., tubular or overflow proteinuria).
✅ 5. KDIGO Albuminuria Categories (A1–A3)
| Category | ACR (mg/g) | Interpretation |
|---|---|---|
| A1 | <30 | Normal to mildly increased |
| A2 | 30–300 | Moderately increased |
| A3 | >300 | Severely increased |
📌 Key Notes
- Persistent albuminuria is a major marker for CKD diagnosis and progression risk.
- Always interpret ACR alongside eGFR for KDIGO G–A categories.
- Avoid testing during acute illness, menstruation, urinary tract infection, fever, or strenuous exercise.
1. According to KDIGO, the preferred initial test for detecting proteinuria is:
A. 24-hour urine protein
B. Spot urine ACR
C. Dipstick protein
D. Timed urine protein
ACR is the KDIGO-preferred test due to accuracy and convenience.
2. KDIGO recommends confirming albuminuria when:
A. ACR is < 30 mg/g
B. Dipstick is 1+
C. Any initial ACR is elevated
D. The patient has hypertension
KDIGO requires repeat ACR for confirmation of any elevated result.
3. Persistent albuminuria is defined as abnormal ACR present in:
A. Two samples 24 hours apart
B. One positive sample
C. ≥2 of 3 samples over 3 months
D. Weekly samples
KDIGO defines chronicity at ≥3 months.
4. First-morning urine is preferred for ACR because:
A. It is more concentrated
B. It reduces biological variability
C. It avoids lab error
D. It measures glucose too
Biological variability is lowest in first-morning ACR.
5. Routine 24-hour urine protein is recommended:
A. For all CKD patients
B. Only when precise quantification is required
C. For diabetes screening
D. For hypertension
KDIGO discourages routine 24-hour collections.
6. KDIGO Albuminuria A2 range is:
A. <30 mg/g
B. 30–300 mg/g
C. 300–1000 mg/g
D. >1000 mg/g
A2 = moderately increased albuminuria.
7. Moderately increased albuminuria corresponds to:
A. A1
B. A2
C. A3
D. A0
A2 = moderately increased albuminuria.
8. Repeat testing is important because ACR has:
A. High biological variability
B. High accuracy
C. Low sensitivity
D. No diagnostic value
ACR may vary day-to-day; repeat testing improves accuracy.
9. Dipstick protein is recommended by KDIGO for:
A. Accurate quantification
B. Screening only
C. Monitoring CKD progression
D. Diagnosing nephrotic syndrome
Dipstick is semi-quantitative and unreliable for diagnosis.
10. Which increases the chance of false high ACR?
A. High fluid intake
B. Fasting
C. Strenuous exercise
D. Walking slowly
Exercise causes transient albuminuria.
11. PCR is preferred over ACR when:
A. Albumin measurement is unavailable
B. In all diabetics
C. In pregnancy
D. In children
PCR is an acceptable alternative when ACR cannot be measured.
12. KDIGO defines A3 albuminuria when ACR is:
A. >100 mg/g
B. >200 mg/g
C. >300 mg/g
D. >30 mg/g
A3 = severely increased albuminuria.
13. ACR results are reported in:
A. mg/L
B. % concentration
C. mg/g or mg/mmol
D. grams per litre
Standard units for albuminuria classification.
14. ACR should NOT be interpreted during:
A. Early morning collection
B. Hydration
C. UTI or fever
D. Sedentary periods
Inflammation and infection falsely elevate albuminuria.
15. Highest CKD risk category is:
A. G2–A1
B. G1–A2
C. G3b–A3
D. G2–A2
Risk is highest with low GFR + high albuminuria.
16. KDIGO recommends repeating ACR to confirm abnormalities because:
A. It is cheaper
B. ACR fluctuates with hydration and exercise
C. It measures glucose
D. ACR is a manual test
Variability can falsely elevate or lower results.
17. Albuminuria in KDIGO is primarily used for:
A. Diagnosing AKI
B. CKD staging and prognosis
C. Calcium metabolism
D. Lipid screening
KDIGO uses GFR + Albuminuria for CKD classification.
18. In which scenario may spot ACR be unreliable?
A. High BMI
B. Extreme muscle mass
C. Sedentary lifestyle
D. Pregnancy
Creatinine excretion varies widely with muscle mass.
19. KDIGO recommends ACR for monitoring:
A. Only diabetes
B. Only hypertension
C. CKD progression and therapy response
D. Hyperkalemia
Albuminuria tracks progression + response to therapy.
20. ACR should be avoided after:
A. Light walking
B. Vigorous exercise
C. Sleeping
D. Eating breakfast
Exercise causes transient albuminuria — avoid testing soon after.
1. What is the preferred initial test for detecting proteinuria according to KDIGO?
Spot urine Albumin-to-Creatinine Ratio (ACR).
2. Why does KDIGO recommend first-morning urine for ACR?
It reduces biological variability and improves reliability.
3. What is the KDIGO definition of persistent albuminuria?
Abnormal ACR in ≥2 of 3 samples over 3 months.
4. What ACR range defines A2 albuminuria?
30–300 mg/g (moderately increased).
5. What ACR defines A3 albuminuria?
>300 mg/g (severely increased).
6. When should ACR not be measured?
During UTI, fever, menstruation, acute illness, or recent strenuous exercise.
7. What is the role of dipstick protein testing?
Screening only, not for diagnosis or quantification.
8. When is PCR (Protein-Creatinine Ratio) acceptable?
When ACR is unavailable or when non-albumin proteins are suspected.
9. When is 24-hour urine protein preferred?
Nephrotic syndrome or need for precise quantification.
10. What ACR cut-off is used to diagnose nephrotic-range albuminuria?
>2200 mg/g.
11. What is the major prognostic value of albuminuria in CKD?
Predicts renal progression, CV risk, and mortality.
12. What albuminuria category is considered normal?
A1 (<30 mg/g).
13. What is the common unit used for ACR reporting?
mg/g or mg/mmol.
14. Which CKD stage requires albuminuria for diagnosis?
G1 or G2 must have ACR ≥30 mg/g to diagnose CKD.
15. What can falsely elevate ACR?
Exercise, fever, dehydration, UTI, menstruation.
16. What can falsely lower ACR?
Dilute urine from high fluid intake.
17. What is the KDIGO recommendation for monitoring ACR in CKD?
At least annually, more frequently in progressive CKD or diabetes.
18. Does KDIGO prefer albuminuria or total protein?
Albuminuria (ACR) is preferred.
19. In which patient group is ACR strongly recommended?
Patients with diabetes, hypertension, or CKD risk factors.
20. What is the earliest marker of diabetic kidney disease?
Moderately increased albuminuria (A2).
21. Which albuminuria category has the highest CV risk?
A3.
22. Why is creatinine used in ACR?
Corrects for urine concentration variability.
23. A patient has ACR 100 mg/g. What category?
A2.
24. A patient has ACR 1500 mg/g. What category?
A3 (severely increased).
25. What defines microalbuminuria in older terminology?
30–300 mg/day or ACR 30–300 mg/g (now A2).
26. What defines macroalbuminuria in old terminology?
>300 mg/day or ACR >300 mg/g (now A3).
27. Should ACR be performed during acute HF exacerbation?
No — acute illness may transiently elevate albuminuria.
28. What is the recommended screening frequency in diabetes?
Type 1: yearly after 5 years
Type 2: yearly from diagnosis
29. What ratio suggests tubular proteinuria rather than glomerular?
High PCR with relatively normal ACR.
30. Why repeat ACR even if high once?
To confirm chronicity, avoiding false positives.
A. Start ACE inhibitor immediately without repeat testing
B. Repeat ACR (first-morning) to confirm persistent albuminuria
C. Order 24-hour urine protein now
D. Treat as A1 and observe yearly
KDIGO recommends confirming any elevated ACR with repeat testing (preferably first-morning) before labeling persistent albuminuria and initiating long-term therapy decisions.
A. This confirms A3 albuminuria
B. Defer interpretation and repeat ACR after infection resolves
C. Start immunosuppression for glomerulonephritis
D. Obtain immediate kidney biopsy
Acute infections (UTI, fever) can transiently raise albuminuria; KDIGO advises repeating ACR after resolution before diagnosing persistent albuminuria.
A. ACR underestimates in low muscle mass due to low creatinine — PCR preferred
B. ACR may overestimate albuminuria relative to true protein excretion because urinary creatinine is low
C. Dipstick is more reliable here
D. 24-hour collection is always superior and required
Low muscle mass lowers urinary creatinine, which can lead to higher ACR values for the same albumin excretion; interpret cautiously and consider alternative quantification if needed.
A. Continue using dipstick for monitoring
B. Spot ACR is sufficient for nephrotic syndrome evaluation
C. 24-hour urine protein may be used when precise quantification is needed (nephrotic range)
D. PCR is contraindicated
While ACR/PCR are convenient, KDIGO allows 24-hour collection when precise total protein quantification matters (e.g., suspected nephrotic syndrome) or spot tests are unreliable.
A. A1 — normal
B. A2 — moderately increased; indicates higher CKD risk and warrants confirmation
C. A3 — severe
D. Cannot be categorized without PCR
ACR 30–300 mg/g is A2 (moderately increased), associated with increased risk — requires repeat confirmation and integrated risk assessment with eGFR.
A. Diagnose CKD immediately
B. Recognize exercise-induced transient albuminuria and repeat ACR after rest
C. Start ACE inhibitor
D. Order kidney biopsy
Strenuous exercise causes transient increases in albuminuria; KDIGO advises retesting when the patient is rested to determine persistence.
A. No action needed
B. Immediate renal replacement therapy referral
C. Initiate or optimize renin-angiotensin blockade and tighten glycemic BP control
D. Start high-dose steroids
Persistent moderately increased albuminuria (A2) in diabetes warrants ACEi/ARB therapy (if indicated) and risk-factor modification per KDIGO recommendations.
A. KDIGO albuminuria categories do not apply in pregnancy and should be ignored
B. Treat as A3 due to pregnancy-related hyperfiltration
C. Interpret cautiously; pregnancy-specific guidance needed (pre-eclampsia/workup) — repeat and correlate clinically
D. Start ACE inhibitor
KDIGO categories inform risk but pregnancy requires obstetric-specific assessment; ACE inhibitors are contraindicated — evaluate for preeclampsia and repeat testing.
A. Use single ACR during AKI to stage CKD
B. Avoid using ACR during acute illness for CKD staging — reassess after recovery
C. ACR is diagnostic for CKD even in AKI
D. Immediately perform 24-hour collection
Acute illness and AKI can alter albuminuria; KDIGO recommends avoiding CKD classification based on tests during acute events — reassess when stable.
A. ACR will accurately capture non-albumin proteins
B. ACR may miss non-albumin proteinuria — consider urine protein electrophoresis or 24-hour protein
C. Dipstick is superior for Bence Jones proteins
D. No additional testing needed
ACR targets albumin; tubular/monoclonal proteins may not be reflected. Use appropriate tests (UPEP, immunofixation, urine protein quantification).
A. PCR is invalid and should not be used
B. PCR is an acceptable alternative when ACR is unavailable
C. Use dipstick instead of PCR
D. Estimate albuminuria from serum albumin
KDIGO accepts PCR as an alternative if ACR measurement is unavailable; be aware of differences when classifying albuminuria.
A. Low risk because ACR is only A2
B. Risk uncertain without biopsy
C. Elevated risk — lower GFR (G4) with any albuminuria increases progression/cardiovascular risk
D. No action if asymptomatic
KDIGO uses combined GFR and albuminuria categories — lower GFR with any albuminuria confers higher CKD progression and CV risk.
A. Treatment failed — stop ACE inhibitor
B. Partial response — continued RAAS blockade and risk factor control indicated
C. Switch immediately to high-dose steroid
D. No further monitoring required
Reduction in albuminuria indicates therapeutic response; continue treatment and monitor — goal is risk reduction, not necessarily normalization.
A. ACR is always accurate in cirrhosis
B. Ascites and low muscle mass may make ACR interpretation unreliable
C. Dipstick detects albuminuria better
D. ACR categories change in cirrhosis
Cirrhosis alters creatinine generation and volume status; ACR should be interpreted cautiously; alternative quantification may be needed.
A. Isolated ACR 45 mg/g in well-controlled diabetic for 5 years
B. ACR 80 mg/g with stable eGFR and no hematuria
C. Rapidly rising proteinuria, active urinary sediment, or suspected non-diabetic glomerulonephritis
D. Mild dipstick positivity only
KDIGO suggests biopsy when clinical features suggest alternative diagnoses (rapidly progressive proteinuria, hematuria, systemic signs) rather than routine isolated albuminuria in stable diabetic nephropathy.
A. Repeat ACR only
B. Urine protein electrophoresis / immunofixation to look for monoclonal proteins
C. CT abdomen to look for malignancy
D. Start steroids
Non-albumin proteins (light chains) require specific tests like UPEP/IFE; ACR can miss these causes of proteinuria (e.g., multiple myeloma).
A. Only eGFR — ignore albuminuria
B. Dipstick monthly
C. Use serial ACR/PCR measurements along with eGFR to assess progression and response
D. Only clinical symptoms
KDIGO supports integrated monitoring using both GFR and albuminuria measures to evaluate disease course and treatment efficacy.
A. Post-exercise urine
B. Very dilute urine from excessive fluid intake
C. UTI
D. Menstruation
Dilute urine lowers albumin concentration relative to creatinine, potentially producing spuriously low ACR values.
A. This is A2; continue routine care
B. A3 — severe albuminuria; correlate with disease activity and consider nephrology/rheumatology evaluation and possible biopsy
C. Ignore due to autoimmune disease
D. Perform 24-hour creatinine clearance
ACR >300 mg/g is A3 (severely increased) — in autoimmune disease this suggests active glomerular disease and warrants prompt specialist assessment and possible biopsy.
A. mg/L only
B. g/day
C. mg/g or mg/mmol
D. mmol/L only
ACR is typically expressed as mg albumin per g creatinine (mg/g) or mg/mmol depending on regional conventions.
A. ACR is sufficient to exclude tubular proteinuria
B. Dipstick will detect glycosphingolipids
C. Consider urine protein electrophoresis and specific tests for tubular proteinuria as ACR may miss non-albumin losses
D. No further testing
Inherited tubular disorders and storage diseases can cause non-albumin proteinuria; targeted testing (UPEP, α-galactosidase assay) may be needed beyond ACR.
A. Consistently A3
B. Borderline variability; needs repeat first-morning ACRs and clinical correlation before labeling persistent albuminuria
C. Ignore values <50
D. Start immunosuppression
ACR has biological variability; KDIGO recommends confirming persistence (≥2 of 3 elevated samples over 3 months) using standardized collections.
A. Immediate dialysis referral
B. Continue conservative care, manage BP, monitor progression (integrate GFR and albuminuria)
C. Start empiric steroids
D. Ignore ACR entirely in elderly
KDIGO recommends individualized management in older adults: balance risks/benefits; control BP, manage comorbidities, and monitor rather than aggressive interventions unless indicated.
A. They are numerically identical always
B. PCR approximates total protein, ACR measures albumin — conversion formulas exist but they are not exact
C. KDIGO bans PCR
D. Use PCR only in children
PCR estimates total protein-to-creatinine; ACR specifically measures albumin; clinical context and standardized reporting matter when comparing results.
A. Attribute to native kidney disease
B. Urgently evaluate for rejection, recurrent disease, infection, or urinary tract issues and consider biopsy
C. No action if eGFR stable
D. Stop immunosuppression immediately
Post-transplant albuminuria signals potential graft pathology (rejection, recurrent disease) and requires prompt evaluation including consideration of biopsy.
A. Dipstick is equivalent to ACR for diagnosis
B. Use dipstick for initial screening but confirm positives with ACR/PCR when available
C. Do not screen at all
D. Start treatment based on dipstick alone
Dipstick may be used for screening in resource-limited settings, but KDIGO recommends confirmation of positives with quantitative tests when feasible.
A. Single elevated ACR during menstruation
B. Either A or any single abnormal result — repeat at least once to confirm unless urgency dictates otherwise
C. Persistent A3 documented twice in 1 week
D. Two normal ACRs
KDIGO emphasizes confirming abnormal ACRs (particularly if single) because acute or transient factors can affect results; repeat testing is recommended before major interventions.
A. Use local unit conventions without conversion
B. Report ACR in mg/g and/or mg/mmol and state assay method for comparability
C. Only report dipstick categories
D. Report as percentage
Standardized units and documentation of assay methods improve comparability across studies; KDIGO supports transparent reporting (mg/g or mg/mmol) and method details.
A. Spot ACR alone
B. 24-hour urine protein collection for precise total protein quantification
C. Dipstick only
D. Serum creatinine clearance
In nephrotic-range proteinuria, 24-hour urine protein helps quantify total protein loss and guide management; spot tests may be misleading in extremes.
A. Albuminuria changes are irrelevant to prognosis
B. Discontinue therapy if albuminuria falls — risk of overdiuresis
C. Reduction in albuminuria is favorable and supports ongoing therapy and monitoring
D. Immediate biopsy required
KDIGO recognizes albuminuria reduction (e.g., with RAAS blockade or SGLT2 inhibitors) as a marker of therapeutic benefit and reduced progression risk; continue therapy with monitoring.
