About Microscopic Hematuria

What Is Microscopic Hematuria?

Microscopic hematuria refers to the presence of red blood cells in the urine, that are not visible to the naked eye. It is typically confirmed by microscopic examination of a properly collected urine sample, commonly defined as three or more red blood cells per high-power field under a microscope. A urine dipstick can suggest blood in the urine, but positive dipstick results should generally be confirmed with urine microscopy. Microscopic hematuria is different from gross hematuria, which means blood is visible in the urine.

Microscopic hematuria may occur with symptoms, such as flank pain, pain with urination, or symptoms of a urinary tract infection, or it may be found when there are no noticeable symptoms. When microscopic hematuria is persistent and is not explained by temporary causes such as exercise, trauma, menstruation, or infection, a health care professional may recommend further evaluation to look for urinary tract or kidney causes. Some studies have linked persistent isolated microscopic hematuria with a higher long-term risk of kidney disease, but the individual risk depends on the underlying cause and other clinical findings.

Causes and Risk Factors for Microscopic Hematuria

Microscopic hematuria can have various possible causes or associated underlying conditions, including:

Glomerular causes: Glomerulonephritis [glom-er-you-loh-nuh-FRY-tis], IgA nephropathy, thin basement membrane nephropathy, and Alport syndrome.
Urinary tract infections: Infections in the urinary tract can lead to microscopic hematuria.
Kidney stones: The presence of kidney stones can cause microscopic hematuria..
Trauma: Injury to the kidneys, bladder, ureters, urethra, or surrounding structures

can result in microscopic hematuria.

Risk factors that cannot be changed may affect the chance of having microscopic hematuria or the chance that it is related to an underlying urinary tract or kidney condition. These include:

Age: The chance of microscopic hematuria and certain underlying causes, including some urinary tract cancers, generally increases with age.
Sex: Males have a higher risk than females of some serious causes of microscopic hematuria, including bladder cancer, although microscopic hematuria can occur in people of any sex.
Family history: A family history of kidney disease or certain inherited conditions that affect the kidneys or urinary tract can increase the need for further evaluation.

Risk factors or exposures that may be changed or reduced include:

Smoking: A history of smoking increases the risk of bladder and other urinary tract cancers, which are important possible causes to consider when microscopic hematuria is found. Quitting smoking can lower future health risks.
High blood pressure: Long-term or poorly controlled high blood pressure can contribute to kidney disease, which may be associated with microscopic hematuria. Managing blood pressure can help protect kidney health.
Certain occupations or exposures: Exposure to some workplace chemicals, such as benzene or aromatic amines, can increase the risk of urothelial cancers, which can cause microscopic hematuria. Reducing exposure and using recommended protective measures may lower risk.

These factors do not mean a person will develop microscopic hematuria or have a serious underlying condition. A health care professional can consider a person’s symptoms, medical history, test results, and risk factors when deciding whether further evaluation is needed.

Symptoms Associated With Microscopic Hematuria

Microscopic hematuria means red blood cells are found in the urine during testing, but the blood is not visible to the naked eye. Microscopic hematuria itself usually does not cause symptoms. When symptoms are present, they are usually related to the condition causing the blood in the urine.

Symptoms that may occur with some causes of microscopic hematuria include:

Pain or burning during urination
Needing to urinate more often or urgently
Pain in the side, back, lower abdomen, or pelvis
Visible blood in the urine or blood clots, which is considered gross hematuria and should be evaluated promptly

These symptoms can be caused by urinary tract infections, kidney stones, prostate conditions, kidney disease, or other urinary tract problems. Contact a health care professional if you have urinary symptoms, persistent microscopic hematuria, or any visible blood in the urine.

How Microscopic Hematuria Is Diagnosed

Microscopic hematuria is diagnosed with urine microscopy, usually when a properly collected urine sample shows three or more red blood cells per high-power field. A urine dipstick can suggest blood in the urine, but a positive dipstick result should generally be confirmed with microscopic urinalysis.

Medical history: A health care professional may ask about urinary symptoms, recent exercise or injury, menstruation or possible sample contamination, infections, kidney disease, smoking history, medication use, and other risk factors.
Physical exam: A physical exam may help look for signs of infection, kidney disease, prostate or gynecologic sources of bleeding, or other conditions that could explain the urine findings.
Urinalysis with microscopy: This test checks the urine for red blood cells and may also look for signs of infection, protein, or other findings that can help guide the next steps.

If a temporary or noncancerous cause is suspected, such as a urinary tract infection or gynecologic bleeding, the health care professional may treat or address that cause and repeat the urinalysis afterward. If microscopic hematuria persists or no clear cause is found, further evaluation may be based on a person’s risk factors.

Urinary tract imaging: Imaging may be used to look at the kidneys and urinary tract. The type of imaging, such as ultrasound or CT urography, depends on the person’s risk level and clinical situation.
Cystoscopy: This procedure lets a urologist look inside the bladder and urethra. It may be recommended for people at intermediate or higher risk for urinary tract cancer or when symptoms or risk factors make bladder evaluation important.
Blood tests and urine culture: Blood tests may check kidney function or look for signs of kidney inflammation or other conditions. A urine culture may be ordered if a urinary tract infection is suspected.

Evaluation is usually individualized. Some people only need repeat urine testing, while others may need imaging, cystoscopy, or kidney-focused evaluation depending on age, sex, smoking history, degree and persistence of microscopic hematuria, symptoms, kidney-related findings, and other risk factors.

How Microscopic Hematuria Is Treated

Microscopic hematuria is treated by addressing the underlying cause, when one is found. The blood in the urine itself usually does not need a specific treatment. The recommended approach depends on the person’s symptoms, test results, risk factors, and diagnosis.

Possible treatments may include:

Antibiotics, if a urinary tract infection is confirmed or strongly suspected
Treatment for kidney stones, which may include pain control, fluids, procedures, or surgery depending on the stone’s size, location, and symptoms
Management of kidney disease, if testing suggests a glomerular or other kidney-related cause

Other care may include:

Treatment of prostate, gynecologic, or structural urinary tract conditions when they are identified as the likely cause
Cancer evaluation and treatment, if a urinary tract cancer is found. Treatment may involve surgery, medicines placed in the bladder, systemic therapy, radiation, or a combination of approaches depending on the cancer type and stage.

Health behavior changes may include:

Quitting smoking, managing blood pressure, staying hydrated when appropriate, and reducing relevant occupational exposures to help lower future urinary tract or kidney health risks

If no concerning cause is found after evaluation, a health care professional may recommend follow-up urine testing or monitoring based on the person’s risk factors and preferences. Anyone who develops visible blood in the urine, worsening urinary symptoms, or a significant change in test results should seek further evaluation.