Bedside Snapshot
- Normal Result
- Negative dipstick and fewer than 3 RBC/HPF on microscopy.
- Significant Result
- 3 or more RBC/HPF (true hematuria), or any gross hematuria. No universal critical value; interpret in context.
- Positive Suggests
- Urinary tract source: stone, infection, cancer
- Glomerular: RBC casts, dysmorphic RBCs, proteinuria
- Pigment: dipstick positive with 0 RBC (hemolysis or rhabdomyolysis)
- Negative Does Not Exclude
- Intermittent bleeding, or high vitamin C intake (ascorbic acid causes false negatives). Use microscopy if suspicion remains.
- Act Now If
- Gross hematuria with clots, hematuria with AKI or flank pain with fever, or dark urine with 0 RBC: urgent evaluation; check CK, creatinine and CBC; urology or nephrology per cause.
- Watch Out For
- A positive dipstick with 0 RBC suggests pigment, but lysed RBCs (dilute or alkaline urine) and bacterial peroxidase can also cause it. Confirm with serum color, CK and hemolysis labs.
Reference & Critical Ranges
Lab-specific ranges: Ranges depend on the lab, the analyzer and the population. Use the range on your own report. The values below are typical only.
Reference ranges
| Population | Conventional | SI | Notes |
|---|---|---|---|
| Adult, dipstick | Negative | Same (no SI conversion) | A positive dipstick requires microscopy |
| Adult, microscopy | <3 RBC/HPF | Same (per high-power field) | 3 or more RBC/HPF on a properly collected single specimen is microhematuria (AUA/SUFU). Critical Care Transport Table 9-3 gives ≤2/hpf as normal. Older emergency-medicine references accepted 2–3 (men) to 2–4 (women) and used 5 RBC/HPF as the threshold of abnormality (Rosen's 8e Ch. 97), so a report of 3–5 RBC/HPF can read as normal on an older interval yet still warrants AUA/SUFU risk stratification |
| Children | Pediatric reference required | — | Adult microhematuria thresholds are not defined for children |
Dipstick grades (free hemoglobin)
| Grade | Hemoglobin (mg/dL) | Meaning |
|---|---|---|
| Negative | <0.01 | No detectable heme pigment |
| 1+ | 0.01–0.03 | Low level; microscopy often needed to explain it |
| 2+ | 0.03–0.06 | Moderate heme pigment or hematuria |
| 3+ | >0.06 | High heme; gross hematuria or pigmenturia likely |
The bands shift from one strip maker to the next. Read the insert for the lot your lab is using.
Critical values: There is no universal critical value. Act on the triggers in the glance card: gross hematuria with clots, hematuria with acute kidney injury or flank pain with fever, and a positive dipstick with no RBCs in a patient with dark urine.
Causes of Abnormal Results
Positive result: causes
| Cause | Common causes | Bedside clue |
|---|---|---|
| Urinary tract bleeding | Stones, UTI, trauma, bladder, kidney or urothelial cancer, BPH, papillary necrosis | Flank pain (stone); dysuria (UTI); painless hematuria in older adults or smokers (malignancy); clots suggest a lower or upper tract source |
| Glomerular bleeding | IgA nephropathy, post-infectious GN, lupus nephritis, ANCA vasculitis, anti-GBM disease, Alport syndrome | RBC casts, dysmorphic RBCs, proteinuria, hypertension, rising creatinine |
| Hemoglobinuria | Intravascular hemolysis: transfusion reaction, hemolytic anemia, PNH, sickle cell disease | Pink to brown urine; 0 RBC on microscopy; check LDH, haptoglobin and smear |
| Myoglobinuria | Rhabdomyolysis: trauma, crush, prolonged immobilization, exertion, seizures, statins, cocaine | Tea- or cola-colored urine; 0 RBC on microscopy; CK markedly elevated |
| Benign and transient causes | Infection, vigorous exercise (“march hematuria”), menstruation, trauma, recent urologic instrumentation, recent sexual activity, viral illness | Usually resolves once the cause clears; exclude these and repeat the urinalysis before a full workup |
| Contamination | Menstrual or vaginal blood, semen | Positive dipstick in a menstruating patient; repeat with a clean-catch or catheter specimen |
| Anticoagulant or antiplatelet therapy; coagulopathy or thrombocytopenia | Contributors that unmask an existing lesion; they do not explain hematuria on their own | Not a diagnosis; investigate the source |
Glomerular vs non-glomerular hematuria
- Glomerular: Expect RBC casts, dysmorphic RBCs and proteinuria, with usually no clots. Thin basement membrane disease is benign, and its RBCs stay uniform. Acanthocytes at 5% or more of excreted RBCs were 98% specific. They were only 52% sensitive for glomerular disease. There is no validated single cut-off for dysmorphic RBCs.
- Non-glomerular: Uniform RBCs, possible clots, little or no proteinuria, and urinary tract symptoms or stones on imaging.
RBC casts: Highly specific for glomerular disease. Once trapped in a tubular protein matrix, the cells give it away. The bleeding began in the glomerulus and passed through the tubule.
Interpretation & Bedside Approach
Step-by-step approach
- Is it real? Check the specimen (clean catch or catheter; menstrual status). Exclude transient benign causes first (infection, vigorous exercise, menstruation, trauma, recent instrumentation, viral illness); send a urine culture if infection is suspected. Centrifuge and count RBC/HPF. A dipstick alone is not diagnostic.
- Blood or pigment? Spin the urine. Hematuria leaves a clear supernatant, and hemoglobinuria and myoglobinuria do not. Pink to red or brown serum points to hemoglobin (intravascular hemolysis). Normal-colored serum with dark urine points to myoglobin. Lysed RBCs in dilute or alkaline urine can also give a positive dipstick with 0 RBC, so check the supernatant.
- Where is the source? Use RBC morphology (dysmorphic RBCs, casts), proteinuria, clots and symptoms.
- Stratify risk: Apply the AUA/SUFU age, RBC count, smoking and gross-hematuria criteria below.
- Escalate or follow up: Act on the red flags now; otherwise follow the risk-based pathway.
Decision table
| Pattern | Suggests |
|---|---|
| Dysmorphic RBCs, acanthocytes or RBC casts | Glomerular disease: nephrology referral; creatinine and further serology per nephrology |
| Uniform RBCs, clots, or stone or infection signs | Non-glomerular (urinary tract) bleeding: urology and imaging |
| Dipstick positive, 0 RBC, pink to brown serum | Hemoglobinuria: CBC, smear, LDH, haptoglobin, direct Coombs test |
| Dipstick positive, 0 RBC, normal-colored serum, dark urine | Myoglobinuria: CK, creatinine, potassium |
| Negative dipstick with RBCs on microscopy | Possible false negative from vitamin C; trust microscopy |
Risk stratification and evaluation (AUA/SUFU microhematuria)
| Risk | Criteria | Evaluation |
|---|---|---|
| Low | ALL of: men under 40 or women under 50; 3–10 RBC/HPF on a single urinalysis; never smoker or under 10 pack-years; no urothelial cancer risk factors | Repeat urinalysis at 6 months; cystoscopy and renal ultrasound are also reasonable |
| Intermediate | ANY one of: men 40–59 or women 50–59; 11–25 RBC/HPF; 10–30 pack-years; persistent 3–10 RBC/HPF after a low-risk result; other urothelial risk factors | Cystoscopy and renal ultrasound (ultrasound preferred over CT urography for radiation and cost; less sensitive for upper-tract cancer) |
| High | ANY one of: age 60 or older; more than 25 RBC/HPF; more than 30 pack-years; history of gross hematuria | Cystoscopy and CT urography; MR urography or retrograde pyelography if contrast is contraindicated |
Once infection, menses and other benign causes are out of the picture, this pathway takes over for asymptomatic microhematuria. A clean repeat urinalysis at 6 months may end the workup. If 3–10 RBC/HPF persists, the patient moves up to intermediate risk. Gross hematuria, the kind you can see, is not handled as microhematuria. It sits in the high-risk group.
Red flags for urgent evaluation:
- Gross hematuria with clots or urinary retention (obstruction)
- Hematuria with acute kidney injury (possible rapidly progressive glomerulonephritis)
- Hematuria with flank pain and fever (possible infected obstruction)
- Dark urine with 0 RBC (possible rhabdomyolysis or hemolysis)
Management Priorities
Emergency: dark urine with 0 RBC, dark urine during or after a transfusion, or hematuria with hemodynamic instability
- Treat the threat first: Manage shock or major bleeding per protocol first. After trauma with hypotension, the hematuria counts as major bleeding until proven otherwise.
- Suspected transfusion reaction: Stop the transfusion now. Keep IV access open with normal saline. Recheck the patient and the unit ID. Tell the physician and the blood bank. Send the unit, tubing and post-reaction samples per institutional policy.
- Suspect rhabdomyolysis or hemolysis: Order CK, creatinine, potassium, CBC, LDH and haptoglobin. CK is commonly treated as markedly elevated above 5 times the upper limit of normal. That is a convention, not a guideline cut-off. Add coagulation studies if anticoagulated. If potassium is high or rising, use cardiac monitoring and a 12-lead ECG.
- Protect the kidneys: Resuscitate with IV fluid per protocol and medical direction. Track urine output and color. Volume overload is the risk in oliguric AKI, heart failure and CKD. Watch for it.
- Escalate: Call nephrology for AKI with hyperkalemia or a dialysis indication. Call urology for obstruction, clots or retention.
Management by cause
- Suspected UTI: Send a urine culture and treat per the culture results. Repeat the urinalysis to confirm the hematuria has cleared. If it persists, it goes into the risk-based evaluation.
- Infected obstruction: A urologic emergency. Drainage is per urology.
- Glomerular disease: Nephrology manages it. Don't start treatment from the dipstick alone.
- Anticoagulated patient: Evaluate the source. Anticoagulant decisions go through the prescriber and local protocol. Hematuria alone is not a reason to skip evaluation.
- Suspected transfusion reaction: Stop the transfusion. Then follow the emergency steps above.
- Stable microhematuria: Risk-based outpatient pathway (Interpretation section).
Management is protocol-dependent. Follow local protocols, medical direction and institutional policy.
Field & Transport Considerations
Point-of-care testing
Field and ED dipsticks are screens. A positive strip is not hematuria until microscopy shows RBCs. Point-of-care results cannot separate blood from pigment. Document the strip result and the urine color. Note that microscopy is pending.
Before and during interfacility transport
- Record: urine color (clear, pink-red, brown or dark), time of void, menstrual status, and anticoagulant or supplement use.
- Specimen: send a clean-catch or catheter specimen with the patient, labelled with time and collection method.
- Re-check: vital signs and urine output during transport; reassess if the urine color changes.
- Trauma: Blood at the meatus, a high-riding prostate, perineal bruising or pelvic fracture: don't pass a catheter blind. Let the trauma team or urology image the urethra first.
- Delay or redirect: clots with retention, hypotension or flank pain with fever call for a receiving team that can drain or image.
Special Populations
| Population | What changes | Clinical implication |
|---|---|---|
| Neonates & infants | Causes and thresholds differ (congenital anomalies, bleeding disorders, infection) | Use pediatric references; do not apply adult AUA thresholds |
| Children & adolescents | Exercise, infection and trauma are common causes | Persistent hematuria, proteinuria or renal impairment needs pediatric nephrology or urology |
| Pregnancy | UTI and pyelonephritis are common | Evaluate infection and obstruction first; prefer ultrasound over CT where possible |
| Older adults | Malignancy risk rises; age 60 or older is a high-risk criterion | Painless hematuria warrants urologic evaluation |
| CKD / dialysis | Baseline hematuria or proteinuria may already be present; contrast risk | Compare with baseline; use MR urography or retrograde pyelography if CT contrast is contraindicated |
| Anticoagulated | Anticoagulation does not explain hematuria; it may unmask a lesion | Evaluate fully; do not dismiss as an anticoagulant effect |
| Menstruating patients | Menstrual blood is a common source of false-positive (contaminated) specimens | Use a clean-catch or catheter specimen; repeat after menses if still unclear |
Adult thresholds: Adults are the population the AUA/SUFU criteria were written for. Pediatric guidance governs children.
Interfering Factors & Pitfalls
Collection & handling
| Factor | Effect | Why | Avoid / fix |
|---|---|---|---|
| Menstrual or vaginal blood | False + | Blood is not from the urinary tract | Clean-catch midstream or catheter specimen |
| Semen or vaginal discharge | False + | Contamination of the specimen | Clean technique; repeat if needed |
| Catheter insertion | True + | Iatrogenic trauma causes real hematuria | Note catheter-related bleeding; re-test after healing |
Medications & supplements
| Factor | Effect | Why | Avoid / fix |
|---|---|---|---|
| High-dose vitamin C | False − | Ascorbic acid inhibits the peroxidase reaction; interference seen at 20 mg/dL in Unic 2018 (both strips tested) | Microscopy if suspicion is high; ask about supplements |
| Anticoagulants | Not a false result | Unmasks existing lesions rather than causing hematuria | Evaluate the source fully |
Physiologic & biologic
| Factor | Effect | Why | Avoid / fix |
|---|---|---|---|
| Myoglobin or free hemoglobin | False + for hematuria | Pigment has the same peroxidase-like reaction as intact RBCs | Microscopy; plasma color; CK |
| Bacterial peroxidase (UTI) | False + | Microbial peroxidases react with the chromogen | Confirm with microscopy; send a urine culture |
| Oxidizing contaminants | False + | Hypochlorite (bleach) reacts with the chromogen | Check container cleanliness |
Assay & device
- In Unic 2018, dipstick specificity for hemoglobin was 62.7–65.6% against a photometric reference method (not microscopy). Positives need microscopy.
Common misinterpretations
- A positive dipstick does not prove hematuria. It can be pigment, lysed RBCs or bacterial peroxidase.
- A negative dipstick does not rule out hematuria. Vitamin C and low sensitivity can both hide it.
- Anticoagulants don't cause hematuria. They expose a source that was already there.
- A normal ultrasound feels reassuring. In high-risk patients it does not end the workup: cystoscopy and CT urography are still needed.
Physiology & Test Basics
What it measures
The pad holds an organic peroxide and a chromogen. Heme in hemoglobin, myoglobin and intact RBCs acts like a peroxidase, and the pad turns yellow, then green, then dark blue. This page covers the blood pad and how to confirm it with microscopy. The other dipstick tests have their own pages.
Physiology & regulation
- RBCs can enter urine from anywhere along the urinary tract. They can also slip through a damaged glomerular filter.
- Glomerular bleeding changes RBC shape as the cells squeeze across the glomerular basement membrane.
- Free hemoglobin from intravascular hemolysis reaches the urine only once haptoglobin is saturated.
- Injured muscle releases myoglobin. The kidney filters it, and large amounts can injure the tubules.
How it is measured
Start with a clean-catch midstream or catheter specimen. Read the dipstick when the manufacturer says to. For microscopy, centrifuge the sample, count RBC/HPF, and look for casts and RBC shape. You don't need to fast.
Why it matters
Hematuria can be the first sign of a treatable urologic or renal disease. Cancer is on that list. Pigment, hemoglobin or myoglobin, can point to life-threatening hemolysis or rhabdomyolysis. Working out which one is present decides the next test.
Scope: Hematuria means RBCs under the microscope. The dipstick color does not define it.
Clinical Pearls
Dipstick positive, 0 RBC, dark urine: think pigment: Check CK now for rhabdomyolysis. Run the hemolysis labs for hemoglobinuria. Plasma color helps tell the two apart.
RBC casts mean glomerulonephritis until proven otherwise: Refer to nephrology urgently. A cast means glomerular inflammation is active.
A normal ultrasound does not close the workup in high-risk patients: Any one of these calls for cystoscopy and CT urography under the AUA/SUFU pathway: age 60 or older, more than 30 pack-years, or prior gross hematuria.
Vitamin C can hide hematuria: Unic 2018 cites earlier studies. Supplement intakes of 350–1000 mg/day can push urine ascorbic acid high enough to interfere with the strip. If suspicion is high, use microscopy.
Clots point away from the glomerulus: Clots suggest a bladder, ureter or renal pelvis source. Glomerular bleeding usually doesn't clot.
Anticoagulation unmasks bleeding; it does not excuse it: Work up hematuria in an anticoagulated patient the same way you would in anyone else.
Prehospital pearl: Write down the urine color and the time of void. Send the specimen with the patient. A field dipstick cannot confirm hematuria.
Nursing pearl: With suspected rhabdomyolysis, follow urine output and color next to the CK, creatinine and potassium trends.
References
- American Urological Association and SUFU (2020, amended 2025). Microhematuria: AUA/SUFU guideline. J Urol. 2020;204(4):778–786. https://www.auanet.org/guidelines/guidelines/microhematuria
- American Family Physician (2021). Microscopic Hematuria in Adults: Updated Recommendations from the American Urological Association. Am Fam Physician. 2021;104(6):655–657. https://www.aafp.org/afp/2021/1200/p655
- Unic A, et al. (2018). Ascorbic acid—A black hole of urine chemistry screening. J Clin Lab Anal. 2018;32(5):e22390. https://pmc.ncbi.nlm.nih.gov/articles/PMC6816895/
- Daza JL, De Rosa M, De Rosa G (2018). Dysmorphic red blood cell formation. Cleve Clin J Med. 2018;85(1):12–13. https://www.ccjm.org/content/85/1/12
- Chavez LO, Leon M, Einav S, Varon J (2016). Beyond muscle destruction: a systematic review of rhabdomyolysis for clinical practice. Crit Care. 2016;20:135. https://doi.org/10.1186/s13054-016-1314-5
- Long B, Koyfman A, Gottlieb M (2019). Evaluation and management of rhabdomyolysis. Am J Emerg Med. 2019;37(3):518–523. https://doi.org/10.1016/j.ajem.2018.12.061
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- For Educational Purposes Only: This content is intended for educational reference and should not be used for clinical decision-making.
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