Causes of WBCs and RBCs in Urine: 7 Common Conditions

Finding blood or unusual cells in your urine can be unsettling, but it doesn’t always mean something serious. You may question what’s causing those white or red blood cells to show up where they shouldn’t—could it be an infection, a stubborn kidney stone, or something else entirely? From UTIs to more complex conditions like lupus, here’s what your body could be trying to tell you at the time things aren’t quite right.

Table of Contents

Urinary Tract Infections (UTIs)

At the time bacteria sneak into your urinary tract, they can cause an infection that triggers your body to send white blood cells (WBCs) to fight it—leading to more WBCs and sometimes red blood cells (RBCs) in your urine.

This is a urinary tract infection (UTI), and it’s one of the most common reasons for these changes in your pee. You may notice symptoms like burning as you urinate, a constant urge to go, or even hematuria (blood in your urine).

Women get UTIs more often because their urethra is shorter, letting bacteria reach the bladder easier. A urinalysis helps confirm the diagnosis by checking for WBCs, RBCs, and bacteria.

Luckily, antibiotics usually clear it up fast, easing discomfort within days. Drink plenty of water to help flush out the infection.

Kidney Stones

Kidney stones can bring on some of the worst pain you’ve ever felt, but they don’t always cause trouble right away. These tiny mineral deposits form in your kidneys and can scrape your urinary tract as they pass, leading to hematuria—blood in your urine (RBCs).

You could also notice WBCs if the stones trigger a urinary tract infection. Sharp back pain, nausea, and frequent urges to pee are common signs.

Dehydration and certain dietary choices, like eating too much salt or oxalate-rich foods, raise your risk. Doctors use imaging tests for diagnosis, and treatment often involves pain relief, drinking plenty of fluids, or procedures to break up larger stones.

Staying hydrated and watching what you eat can help prevent them.

Glomerulonephritis

As your kidneys’ tiny filters, called glomeruli, get inflamed, it’s called glomerulonephritis—and it can sneak up on you. This condition often stems from infections or autoimmune diseases, damaging your kidney function and letting red blood cells and white blood cells leak into your urine (hematuria).

You may notice foamy urine from proteinuria or swelling (edema) in your legs. High blood pressure (hypertension) can also signal trouble. A urinalysis helps spot these issues promptly.

While it sounds scary, treatments like medications or lifestyle changes can manage symptoms and protect your kidneys. Stay alert for signs like fatigue or puffiness, and don’t skip check-ups—catching it promptly makes a big difference.

Your kidneys work hard, so give them the care they deserve.

Bladder or Kidney Cancer

Finding blood or white blood cells in your urine can be unsettling, and while glomerulonephritis is one possible cause, bladder or kidney cancer could also be behind these changes.

Should you notice hematuria (blood in the urine) or leukocyturia (white blood cells in urine), it could signal tumors in your urinary tract. Bladder cancer often shows up as painless hematuria, with RBCs appearing in your urinalysis.

Kidney cancer can also cause blood in the urine, though it’s less common. Both cancers can trigger inflammation, raising WBC levels.

Don’t panic—many conditions cause these changes—but do see a doctor should they persist. Tests like imaging or cystoscopy can check for tumors. Prompt identification improves results, so don’t ignore unusual signs.

Trauma to the Urinary Tract

Should you’ve had a hard fall, a sports injury, or even a car accident, you could notice blood or white blood cells in your urine—and that’s a sign your urinary tract could’ve taken a hit.

Trauma to the urinary tract, like kidney injuries or bladder damage, often causes hematuria (blood in urine) or abnormal blood cells. Even microscopic hematuria—where you can’t see the blood—needs attention.

Here’s what to know:

Symptoms: Along with blood in urine, you could feel abdominal pain, flank discomfort, or trouble peeing.
Medical evaluation: A doctor might order imaging (like CT scans) to check for internal bleeding or organ damage.
Follow-up testing: Even though symptoms fade, you’ll need tests to rule out concealed issues.

Don’t ignore it—trauma can linger unseen. Get checked promptly.

Systemic Diseases (e.g., Lupus)

Trauma isn’t the only reason blood or white blood cells show up in your urine—sometimes, systemic diseases like lupus are behind it. Systemic lupus erythematosus (SLE) can trigger inflammation in your kidneys, a condition called lupus nephritis. At the point this happens, your urine might contain abnormal levels of WBCs, RBCs, or even protein (proteinuria). Hematuria, or blood in your urine, is another red flag. A urinalysis helps spot these signs promptly, preventing worse kidney damage.

Symptom	What It Means	Why It Matters
Proteinuria	Excess protein in urine	Signals kidney stress
Hematuria	Blood in urine	Indicates inflammation
High WBCs	White blood cells in urine	Suggests infection or SLE

If you notice these changes, don’t wait—talk to your doctor. Prompt action can protect your kidneys.

Strenuous Physical Activity

Should you have pushed yourself hard during a workout, you may notice exercise-induced hematuria, where RBCs and WBCs show up in your urine.

Intense activity can bruise your urinary tract or cause dehydration, temporarily raising these levels.

Don’t panic—it usually clears up on its own, but in the event it sticks around, it’s worth checking with a doctor.

Exercise-Induced Hematuria

Exercising hard can sometimes lead to a surprising sight—blood in your urine. This condition, called exercise-induced hematuria, often happens after strenuous physical activity, especially in athletes or those playing contact sports. The impact from running or jumping can irritate your bladder, while dehydration makes your urine more concentrated, adding to the irritation.

Here’s what you should know:

Common causes: Intense workouts, dehydration, or high-impact sports can cause tiny amounts of blood in your urine.
Self-limiting: It usually clears up on its own within a few days once you rest and hydrate.
Whenever to worry: If the blood sticks around (persistent hematuria), get a medical evaluation to rule out other issues.

Most times, it’s harmless, but listen to your body and take breaks whenever needed.

Impact on Urinary Tract

At the time you push your body hard during a workout, your urinary tract can sometimes take a hit, leading to traces of blood or white blood cells in your urine.

Intense exercise, like running or weightlifting, can stress your kidneys and bladder, causing red blood cells to leak into your urine—a condition called exercise-induced hematuria.

Dehydration or repeated impact during high-intensity workouts might also irritate your urinary tract, raising inflammation and WBCs.

While this is often temporary, elevated levels of blood or WBCs could signal a mild urinary tract infection or kidney strain.

Should you notice persistent hematuria or discomfort, don’t ignore it—get a medical evaluation to rule out serious issues.

Staying hydrated and pacing yourself helps reduce the risk.

Post-Workout RBC Levels

Strenuous workouts can sometimes leave more than just sore muscles—they could also lead to red blood cells (RBCs) showing up in your urine. This condition, called exercise-induced hematuria, often happens after high-impact sports or intense sessions.