Understanding Microscopic Hematuria: When Should You Be Concerned About Blood in Your Urine?

Finding blood in your urine can be alarming—but what if you can’t even see it?

Microscopic hematuria refers to the presence of red blood cells in the urine that are not visible to the naked eye but are detected during a routine urine test. For many patients, this condition is discovered by accident—during an annual physical, a job screening, or after a visit to urgent care for an unrelated issue.

So what causes microscopic hematuria, when is it serious, and when should you see a urologist? Let’s break it down.

What Is Microscopic Hematuria?

Microscopic hematuria means that red blood cells are present in your urine, but not in quantities large enough to discolor it. This contrasts with gross hematuria, where blood is visible—turning the urine pink, red, or cola-colored.

Hematuria is not a disease itself; it’s a symptom of an underlying condition. Some causes are benign, while others may signal serious medical problems that require immediate attention.

How Is It Diagnosed?

Microscopic hematuria is most commonly detected during:

• Urinalysis: A simple dipstick test in the doctor’s office or lab.

• Urine microscopy: A more detailed exam under a microscope to confirm red blood cells are present and to evaluate their shape (which can offer clues about the source of bleeding).

If red blood cells are consistently found in at least two of three properly collected urine samples, your doctor may diagnose persistent microscopic hematuria.

Common Causes of Microscopic Hematuria

Not all cases are serious—but some are. Here are potential sources, ranging from benign to concerning:

Benign or Temporary Causes:

• Exercise-induced hematuria (common after long-distance running)

• Recent sexual activity

• Menstruation contamination

• Mild dehydration

• Urinary tract infection (UTI) or inflammation

Structural or Medical Causes:

• Kidney stones – Can irritate the urinary tract and cause bleeding.

• Enlarged prostate (BPH) – A common cause in older men.

• Urinary tract infections – Especially in women or catheterized patients.

• Bladder or kidney trauma – From injury or surgery.

More Concerning Causes:

• Bladder cancer

• Kidney cancer

• Urothelial carcinoma (lining of the urinary tract)

• Glomerulonephritis – A kidney condition often associated with autoimmune diseases.

• Polycystic kidney disease

• Vascular abnormalities or blood disorders

Sometimes, despite extensive testing, no identifiable cause is found—this is known as idiopathic hematuria, which is typically monitored over time.

When Should You Be Concerned?

While many causes of microscopic hematuria are harmless, others are not. So when should you take it seriously?

You should see a urologist if you:

• Have microscopic hematuria confirmed on multiple tests

• Are over 35 years old (as cancer risk increases with age)

• Have risk factors like smoking, chemical exposure (e.g., dyes, solvents), or a history of bladder cancer

• Experience additional symptoms like:
  • Pain during urination

  • Lower back or flank pain

  • Fatigue or unexplained weight loss

  • Visible blood in the urine

Even in the absence of symptoms, persistent microscopic hematuria should be evaluated.

What to Expect During Evaluation

Your urologist will tailor your evaluation based on your age, sex, risk factors, and medical history. Diagnostic steps may include:

• Repeat urinalysis and urine culture to rule out infection

• Imaging tests, such as:
  • CT urogram – Detailed images of the kidneys, ureters, and bladder

  • Renal ultrasound – Especially in younger patients or those with lower cancer risk

• Cystoscopy – A scope inserted into the bladder to look for tumors, stones, or other abnormalities

• Blood tests to check kidney function and rule out systemic conditions

For younger patients with no risk factors and a benign history, less extensive testing may be recommended. However, for older adults or those with concerning features, a full urologic evaluation is critical.

Is It Treatable?

Treatment depends entirely on the underlying cause. For example:

• Infections are treated with antibiotics.

• Stones may pass on their own or require surgical removal.

• Cancer, if diagnosed early, often has a better prognosis and may be treated with surgery, chemotherapy, or other therapies.

• In many cases, especially when the cause is benign or idiopathic, no treatment is necessary, but regular monitoring is advised.

Final Thoughts

Microscopic hematuria may seem like a minor, silent finding—but it shouldn’t be ignored. While it’s often harmless, it can sometimes be the first sign of something more serious, including cancer or kidney disease.

Early detection can make all the difference.

If you’ve been told you have microscopic hematuria, don’t wait for symptoms to get worse. Schedule an appointment with a urologist who can conduct a thorough evaluation and help you understand what’s going on behind the scenes.

Your urinary health is too important to overlook—especially when something as small as a few red blood cells could be trying to tell you something big. We recommend urologist brooklyn.