What does it measure?
The dipstick reacts to heme, the pigment found in hemoglobin and in muscle myoglobin. It can become positive from intact red cells, free hemoglobin, or myoglobin. That is why a strip result and the number of red cells seen under a microscope are different findings. [2]
Before the test
- Sample
- Collect urine in the laboratory’s container, following its clean-catch instructions.
- Mention
- Tell the clinician if you are menstruating or recently did strenuous exercise.
What can the result mean?
A positive result may accompany urinary bleeding, recent hard exercise, contamination, or muscle injury. A negative strip does not replace assessment of persistent visible blood. The next question is whether microscopy confirms red blood cells. [1]
When is it useful, and how is it read?
Start with whether microscopy confirms red cells, then consider symptoms, menstrual contamination, recent exercise, and persistence. Visible bleeding or repeated confirmed microscopic blood needs assessment based on the person’s history and risk factors. [1] [2] [4]
Reading the results together
| Marker | What it adds |
|---|---|
| Urine Blood | A chemical screening result for blood-related pigment. |
| Urine RBCs (microscopic) | Checks for red cells themselves. |
A positive strip is a reason to check the microscopic finding, not a complete diagnosis. [2] [3]
What can affect it?
Menstruation, recent urinary procedures, sample handling, and some supplements can affect results. Share those details rather than assuming a positive strip proves a kidney problem. [1]
Myth: «A positive blood strip proves red cells are present»
The strip also reacts to free hemoglobin and muscle myoglobin. Microscopy checks for intact red cells and helps clarify what produced the positive signal. [1] [2] [4]
Questions you might have
Can blood be present even when urine looks normal?
Yes. Microscopic amounts may be invisible; the test can detect them. [1] [2]
Does a positive strip confirm red cells?
No. A positive strip needs microscopy to establish whether red blood cells are present. [2]
What comes next?
Your clinician may repeat a clean-catch sample or review microscopy and kidney tests. Persistent confirmed blood needs evaluation. Visible blood with clots, difficulty urinating, or severe pain warrants prompt care. [1] [2]
Were red cells actually seen under the microscope, or did only the dipstick react?
The reference interval and units on your report are part of understanding your result. Understand units, reference intervals, and treatment targets.
Sources & references
Medical references & original research
- MedlinePlus — Blood in urine
- AUA/SUFU — Microhematuria Guideline, amended 2025
- MedlinePlus — RBC urine test
Books we consulted
References that informed our explanations of the test and its context.
- McPherson RA, Pincus MR, editors. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2022.
Practical-section sources accessed: .
For general health education. Interpreting your result and deciding on tests or treatment requires your health context and a qualified clinician.
