Blood in the Urine with No Infection
Blood found on a dipstick with no sign of infection needs following up, and how urgently depends mostly on whether you could see it and how old you are. NICE sets urgent referral at 45 and over for visible blood with no infection behind it, and at 60 and over for invisible blood alongside pain on passing urine or a raised white cell count.
The pattern on your report
- Urine blood High · mild Key
- Urine leukocytes Normal Key
- Urine nitrites Normal Key
- Urine protein Normal Key
Printed as: Urine leukocytes in dipstick gradeUrine nitrites in dipstick gradeUrine blood in dipstick grade— Reported as negative, trace or plus signs, and it measures concentration, so how dilute the sample was affects the result.Urine protein in dipstick grade— A concentration measure. The albumin-to-creatinine ratio is the version that corrects for dilution.
Why the numbers look like this
The dipstick detects hemoglobin, not red cells, which is the source of most of the confusion around this test. Anything containing heme turns it positive: intact red cells, free hemoglobin from cells that have broken down in the urine, and myoglobin released from damaged muscle. Microscopy is what separates them by actually looking for cells.
Where the blood joins the stream matters more than how much there is. Bleeding from the kidney's filter arrives with protein and with red cells that have been deformed squeezing through, while bleeding from the bladder or prostate arrives as ordinary-looking cells with no protein. That distinction sends the investigation down two different routes.
The quantity, meanwhile, says almost nothing about the cause. A tumor can bleed once, invisibly, and stop.
Not being flagged is not the same as normal
A dipstick reports concentration, so a dilute sample can read negative while a concentrated one reads trace, and a trace result on a first morning sample is not the same finding as a trace on a sample taken after drinking two liters. It is also sensitive enough to turn positive after hard exercise or during menstruation, which is why a single positive in those circumstances is repeated rather than investigated. What does not follow is the reverse: a positive dipstick with no red cells on microscopy is a real finding, because it points at myoglobin or free hemoglobin instead.
What else on the report can hide this
Protein alongside the blood changes the destination. Blood and protein together point at the glomerulus and belong with a kidney specialist; blood alone points at the urinary tract and belongs with a urologist. Sending someone to the wrong one costs months.
Kidney function and blood pressure are part of the same assessment for that reason, and a rising creatinine with blood and protein is the combination that moves fastest.
Smoking history deserves asking about directly, since it is the dominant risk factor for bladder cancer and it changes the threshold for investigating. So does exposure to aromatic amines in dye, rubber and leather work, which is historical for many people but still relevant. Check whether anticoagulants are being taken, too: they do not cause bleeding from a healthy tract, so blood in the urine on warfarin or a DOAC is investigated exactly as it would be without them.
What usually causes it
Listed from most to least common — not from most to least serious.
- Very common
Exercise, menstruation or a recent catheter
All produce transient blood with nothing wrong. A repeat sample taken away from those circumstances resolves it, and that repeat comes before any referral.
- Very common
Kidney or bladder stones
Classically severe one-sided flank pain coming in waves, but small stones can bleed silently. Imaging finds them.
- Common
An enlarged prostate — in men, increasingly with age
Common, benign, and it bleeds. It remains a diagnosis of exclusion, because prostate enlargement and bladder cancer occur in the same population.
- Common
Bladder or kidney cancer — in risk rises sharply with age and smoking
The reason this pattern has a referral pathway attached. Painless visible blood is the classic presentation, and it can be a single episode that then stops.
- Common
IgA nephropathy or another glomerular disease
Blood arriving with protein, sometimes visible during or just after a throat infection. Deformed red cells or casts on microscopy point here.
- Common
A urinary infection despite the negative dipstick
Not all organisms produce nitrites, so a negative strip does not exclude infection. Culture settles it before anything else proceeds.
- Uncommon
Anticoagulants unmasking a lesion
They do not cause bleeding from a normal urinary tract. Blood in the urine on an anticoagulant is investigated the same way it would be without one.
- Uncommon
Sickle cell trait — in people of African ancestry
Causes painless bleeding from the kidney medulla, and it explains a finding that would otherwise drive repeated investigation.
- Uncommon
Schistosomiasis — in people who have lived in or traveled to endemic regions
A leading cause of blood in the urine worldwide and a risk factor for bladder cancer. Residence history is the clue.
What is usually checked next
- Repeat the dipstick on a fresh sample, away from exercise or menstruation A large share of positives are transient. Repeating first avoids a referral that was never needed.
- Urine culture Excludes infection, which a negative nitrite does not do on its own.
- Urine microscopy Confirms that red cells are actually present, and their shape distinguishes a kidney source from a bladder one.
- Urine ACR, kidney function and blood pressure Protein alongside blood sends this to nephrology instead of urology, which is the most consequential branch here.
- Imaging and cystoscopy where the referral criteria are met Looks directly at the kidneys and bladder. Which of these applies depends on age, visibility and smoking history.
When to seek care sooner
- Emergency Unable to pass urine at all
- Emergency Severe one-sided flank pain with fever
- Same day Blood with clots in the urine
- Same day Blood and protein together, with a rising creatinine
- Soon Visible blood in the urine, at any age
- Soon Unintentional weight loss, or a mass felt in the abdomen
Questions worth bringing to your appointment
- Should this be repeated before anything else, given when the sample was taken?
- Has a culture been sent, and has microscopy looked for actual red cells?
- Was there protein as well, and does that change who I should see?
- Given my age and whether I have smoked, do I meet the referral criteria?
- Does being on an anticoagulant change the plan?