Seeing blood in your urine is alarming. The red, pink, or brown discolouration triggers an immediate and understandable concern: what is causing this, and how serious is it?
For many people, the answer is a urinary tract infection one of the most common medical conditions globally, and the most frequent cause of blood in the urine. But hematuria, the medical term for blood in the urine, has a long list of possible causes. Some are minor and resolve with straightforward treatment. Others are significant enough that they should never be left uninvestigated simply because a UTI was also present.
Understanding the connection between hematuria causes and urinary tract infections and knowing when blood in the urine requires more than antibiotic treatment is what this guide is for.
What Is Hematuria?
Hematuria is the presence of red blood cells in the urine. It is not a diagnosis. It is a symptom, and the diagnosis is whatever is causing the bleeding.
It appears in two forms:
Gross hematuria is visible to the naked eye. The urine appears pink, red, or cola-coloured. Even a small amount of blood as little as one millilitre per litre of urine is enough to produce a visible colour change.
Microscopic hematuria is not visible but is detectable when urine is examined under a microscope. It is defined as three or more red blood cells per high-power field on microscopy. Many people with microscopic hematuria have no symptoms at all and discover it only on a routine urine test.
Both forms require clinical evaluation to identify the cause. The 2025 AUA guideline for hematuria the most significant update to its management in years specifically emphasises that even microscopic hematuria, particularly in higher-risk patients, should never be dismissed without proper investigation.
How UTIs Cause Hematuria
The connection between UTIs and hematuria is direct and well-established. UTIs are the single most common cause of hematuria.
When bacteria infect the lining of the urinary tract, they cause inflammation and irritation. The inflamed lining becomes fragile and bleeds. This produces blood in the urine often accompanied by the other classic symptoms of a UTI: burning or stinging urination, frequent urge to urinate with little output, cloudy or strong-smelling urine, and pelvic discomfort.
The degree of bleeding from a UTI varies. Some patients have clearly visible pink or red urine. Others have only microscopic hematuria identified on a dipstick test at the clinic.
Which Types of UTI Most Commonly Cause Hematuria?
Cystitis (bladder infection) is the most common UTI and the most common source of hematuria associated with infection. Bacteria, most frequently E. coli, colonise the bladder lining, causing the inflammation and bleeding that produces pink or red urine alongside the typical lower urinary tract symptoms.
Pyelonephritis (kidney infection) is a more serious UTI involving the kidneys. It causes more significant bleeding and is accompanied by fever, chills, flank pain (in the back, below the ribs), and often nausea or vomiting. Hematuria from pyelonephritis typically resolves with antibiotic treatment, but the upper tract involvement means the infection requires a longer treatment course and closer monitoring than simple cystitis.
Urethritis (infection of the urethra), more commonly seen in sexually active individuals and sometimes associated with sexually transmitted infections, also causes hematuria alongside urethral discharge and burning.
The Important Question What If the Hematuria Is Not From a UTI?
This is where clinical judgement becomes critical, and where patients sometimes fall through the gap. Hematuria that coincides with UTI symptoms, responds to antibiotic treatment, and resolves completely is most likely UTI-related. But hematuria that persists after the UTI has been treated, or that occurs without any other UTI symptoms, requires investigation for the other hematuria causes some of which are serious.
All the Other Hematuria Causes Worth Knowing
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Kidney stones (nephrolithiasis) Stones in the kidney or ureter scratch and irritate the lining of the urinary tract as they move, causing bleeding. Kidney stone hematuria is classically associated with severe, colicky flank pain that comes in waves and may radiate to the groin, and often with nausea and vomiting. Some small stones cause intermittent hematuria with minimal pain.
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Glomerulonephritis Inflammation of the glomeruli, the kidney's filtering units, causes blood and protein to leak into the urine. It can present as cola-coloured urine, hypertension, and swelling (oedema). Glomerulonephritis has multiple causes including autoimmune conditions such as lupus, IgA nephropathy (the most common primary glomerular disease globally), and post-infectious glomerulonephritis following streptococcal infection. It is one of the more important hematuria causes to exclude through blood and urine testing.
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Bladder and kidney tumours This is the hematuria cause that clinicians are most vigilant about not missing. Bladder cancer is the most common urological malignancy to present with hematuria. It frequently causes painless gross hematuria — blood in the urine without any other symptoms. The absence of pain does not indicate a benign cause. The 2025 AUA guideline update places particular emphasis on risk-stratifying hematuria patients to ensure those at higher risk of malignancy are promptly investigated with cystoscopy and upper tract imaging.
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Enlarged prostate (benign prostatic hyperplasia) In men, an enlarged prostate can cause hematuria through increased vascularity of the prostate tissue and mechanical irritation of the bladder neck. This is a particularly relevant hematuria cause for men over 50 presenting with blood in the urine alongside lower urinary tract symptoms such as incomplete bladder emptying, weak stream, or nocturia.
Medications Several medications cause hematuria either by directly irritating the urinary tract or by impairing clotting:
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Anticoagulants including warfarin, heparin, and direct oral anticoagulants (DOACs)
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Aspirin and NSAIDs
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Certain antibiotics including penicillin and sulfa-containing drugs
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Cyclophosphamide, used in chemotherapy, causes haemorrhagic cystitis
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Certain blood thinning medications used in cardiac conditions
Any patient on these medications who develops hematuria should be reviewed clinically, because the medication may be contributing but should not be assumed to be the sole cause without investigation.
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Exercise-induced hematuria Strenuous exercise, particularly long-distance running, can cause transient hematuria that resolves within 24 to 48 hours of rest. The mechanism involves direct bladder trauma from repetitive impact, reduced renal blood flow during exercise, and myoglobinuria from muscle breakdown. This is a benign, self-limiting condition but should only be attributed to exercise after other causes have been considered.
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Endometriosis In women, endometriosis affecting the urinary tract, particularly the bladder, can cause cyclical hematuria that occurs at the same time as menstruation. This is an underrecognised hematuria cause that may require gynaecological as well as urological assessment.
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Renal tuberculosis In India, genitourinary tuberculosis is a significant cause of hematuria that is frequently missed because it is painless, produces a typical "sterile pyuria" on urine testing (white cells without bacteria on standard culture), and may not have obvious symptoms of systemic tuberculosis. Any patient with persistent hematuria, sterile pyuria, and a history of tuberculosis or high-risk exposure should be specifically tested for genitourinary TB.
UTI-Related Hematuria vs. Hematuria From Other Causes Key Differences
Distinguishing UTI hematuria from other hematuria causes helps guide the urgency of further investigation.
Suggests UTI hematuria:
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Burning or stinging urination present alongside the blood
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Increased frequency and urgency of urination
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Cloudy, strong-smelling urine
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Low-grade fever (particularly if upper tract involved)
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Resolves completely within 48 to 72 hours of antibiotic treatment
Suggests investigation for other causes:
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Blood in the urine without burning, urgency, or other UTI symptoms
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Hematuria that persists after antibiotic treatment has cleared the infection
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Painless gross hematuria in a patient over 40 this requires cystoscopy to exclude bladder cancer
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Cola-coloured urine with facial swelling and reduced urine output (suggests glomerulonephritis)
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Cyclical hematuria in women corresponding to the menstrual cycle
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Blood in urine with severe flank or loin pain (suggests kidney stone)
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Microscopic hematuria discovered incidentally without other symptoms
When to Seek Medical Attention for Hematuria
Blood in the urine should always prompt a medical assessment, even when it is brief, small in volume, or accompanied by obvious UTI symptoms. Seek same-day or urgent assessment for:
Any episode of visible blood in the urine (gross hematuria), regardless of whether UTI symptoms are present
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Hematuria in men of any age UTI is less common in men, and hematuria in males requires specific evaluation
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Hematuria in anyone over 40, particularly with a history of smoking, which is a major risk factor for bladder cancer
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Hematuria with severe flank pain and fever (possible kidney infection or obstructing stone)
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Hematuria alongside facial swelling, reduced urine output, or recent sore throat (possible glomerulonephritis)
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Hematuria that returns after apparently successful UTI treatment
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Any microscopic hematuria identified on a urine test in a patient with risk factors for bladder cancer, kidney disease, or structural urinary tract abnormality
Do not delay simply because:
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The blood was only noticed once and then urine returned to normal colour
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There was no pain (painless hematuria is a specific warning sign, not reassurance)
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A UTI was diagnosed and treated hematuria persisting after treatment needs further evaluation
How Hematuria Is Investigated
A thorough hematuria evaluation involves several layers of investigation, guided by the patient's age, risk factors, and the presence or absence of other symptoms.
Standard Investigations
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Urine dipstick test confirms the presence of blood and assesses for infection (white cells, nitrites, bacteria).
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Urine microscopy and culture confirms or excludes bacterial infection, identifies the causative organism, and guides antibiotic selection.
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Blood tests including full blood count, kidney function (creatinine, eGFR), and a protein-creatinine ratio assess whether kidney disease is contributing. Anti-streptolysin O (ASO) titre is checked when post-infectious glomerulonephritis is suspected.
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Urine cytology examines shed cells in the urine for malignant characteristics and is used in intermediate and high-risk hematuria evaluation.
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Abdominal ultrasound assesses the kidneys and bladder for structural abnormalities, stones, masses, and hydronephrosis.
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CT urogram provides the most detailed imaging of the entire urinary tract and is the investigation of choice when kidney stones, upper tract tumours, or complex anatomy is suspected.
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Cystoscopy directly visualises the inside of the bladder and is the definitive investigation for excluding bladder cancer. The 2025 AUA guideline recommends cystoscopy for intermediate and high-risk hematuria patients, with the risk classification based on age, sex, smoking history, and degree of hematuria.
Treatment It Depends Entirely on the Cause
There is no single treatment for hematuria because hematuria itself is a symptom. Treatment is directed at the underlying cause.
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UTI-related hematuria: Antibiotics targeted to the organism and sensitivity. Bladder hematuria from simple cystitis typically resolves within 48 to 72 hours of starting treatment. Kidney infections require a longer course.
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Kidney stone hematuria: Pain management, hydration, and depending on stone size, watchful waiting, lithotripsy, or ureteroscopic stone removal.
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Glomerulonephritis: Depends on the specific type. Immunosuppressive therapy, blood pressure management, and in some cases targeted treatment of the underlying cause (such as antimalarials for lupus nephritis).
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Bladder or kidney tumour: Surgical management, with cystoscopic resection for superficial bladder tumours or radical surgery and systemic therapy for more advanced disease.
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Medication-related hematuria: Review and adjustment of the causative medication in consultation with the prescribing clinician.
Assessment at Humayun Hospital, T Nagar
At Humayun Hospital, T Nagar, Chennai, we take hematuria seriously — regardless of whether a UTI is also present.
Our urology and internal medicine team provides:
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Urine microscopy and culture with sensitivity-guided antibiotic selection
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Blood testing for kidney function, inflammatory markers, and glomerular disease assessment
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Abdominal ultrasound and CT urogram for structural evaluation
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Urine cytology and cystoscopy referral for patients meeting AUA guideline criteria for intermediate or high-risk hematuria
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Specific genitourinary tuberculosis testing for patients with persistent hematuria and sterile pyuria in the context of the Indian disease environment
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Clear follow-up planning to confirm hematuria resolution after UTI treatment
Blood in the urine is not something to dismiss after a single course of antibiotics without confirmation that it has fully resolved. We are here to ensure that the evaluation goes as far as it needs to and no further than necessary.
Chat with our medical care assistant for quick guidance and support.
