Microscopic hematuria refers to the presence of red blood cells in urine that are not visible to the naked eye. This condition is often detected incidentally during a routine urine test performed for other health assessments. While finding blood in urine can understandably cause concern and anxiety, it is frequently a benign finding. Nevertheless, its discovery always warrants further investigation to determine the underlying cause.
Defining Microscopic Hematuria
Microscopic hematuria is typically discovered during a urinalysis, a common laboratory test that examines a urine sample. Unlike gross hematuria, where blood is visibly present in the urine, microscopic hematuria means the red blood cells can only be seen under a microscope. The threshold for diagnosis typically involves detecting three or more red blood cells per high-power field in a properly collected urine sample.
Range of Potential Causes
The causes of microscopic hematuria vary widely, ranging from completely harmless conditions to more serious underlying health issues. Common and often benign causes include strenuous exercise, temporary dehydration, or certain medications like blood thinners. In women, menstruation can also lead to a false positive result. For men, benign prostatic hyperplasia, an enlargement of the prostate gland, can sometimes cause microscopic bleeding.
Urinary tract issues are another frequent source of microscopic hematuria. Kidney stones, also known as nephrolithiasis, can irritate the lining of the urinary tract, leading to bleeding. Urinary tract infections (UTIs) are a common culprit, causing inflammation in the bladder (cystitis) or kidneys (pyelonephritis) that can result in red blood cells appearing in the urine. Inflammation of the urethra or prostate can also contribute to this finding.
Kidney-specific conditions may also manifest with microscopic hematuria. Glomerular diseases, which affect the tiny filtering units within the kidneys, can lead to blood leaking into the urine. Examples include IgA nephropathy, a common form of glomerulonephritis, and thin basement membrane disease. Polycystic kidney disease, an inherited disorder characterized by numerous fluid-filled cysts in the kidneys, can also cause bleeding.
While less common, more serious concerns include cancers of the urinary tract. Cancers of the bladder, kidney, or prostate can present with microscopic hematuria, sometimes even before other symptoms appear. Inherited disorders, such as Alport syndrome, which affects kidney function and can also impact hearing and vision, may also be a cause. Additionally, trauma or injury to the urinary system, even minor, can lead to the presence of red blood cells in urine.
Identifying Serious Concerns
Certain symptoms or circumstances can indicate a higher likelihood of a serious cause for microscopic hematuria. Persistent pain in the back, side, or abdomen, especially if severe, warrants immediate medical attention. The presence of fever, unexplained weight loss, or difficulty urinating are also concerning signs that suggest a more significant issue. Visible blood in the urine is always a serious symptom requiring prompt evaluation.
Even in the absence of other symptoms, persistent microscopic hematuria requires thorough investigation. This is particularly true for individuals with risk factors for urinary tract cancers, such as a history of smoking or exposure to certain industrial chemicals. While many cases are benign, healthcare providers aim to avoid overlooking potentially serious conditions. Any finding of microscopic hematuria should prompt a discussion with a healthcare professional.
The Diagnostic Process
When microscopic hematuria is detected, a healthcare provider will typically begin with a detailed medical history, asking about symptoms, past medical conditions, and medications. A physical examination will also be performed to assess overall health and identify abnormalities. A repeat urinalysis is often done to confirm the presence of red blood cells and rule out temporary factors or contamination.
Blood tests are commonly ordered to assess kidney function, which might include measuring creatinine and urea levels. A complete blood count (CBC) can also provide insights into overall health and detect signs of infection or anemia. Imaging studies are frequently used to visualize the urinary tract. An ultrasound of the kidneys and bladder is a common initial imaging test, while a CT scan of the abdomen and pelvis might be used for more detailed views.
For certain cases, more specialized tests may be necessary. Cystoscopy, a procedure where a thin, lighted tube with a camera is inserted into the urethra to examine the bladder and urethra, may be performed to directly visualize the bladder lining. In situations where kidney disease is suspected, a kidney biopsy, involving the removal of a small tissue sample for microscopic examination, might be considered. These diagnostic steps help pinpoint the cause of the hematuria.
Treatment and Follow-Up
The treatment for microscopic hematuria depends entirely on the identified underlying cause. If a urinary tract infection is diagnosed, a course of antibiotics will typically resolve the bleeding. For benign causes, such as exercise-induced hematuria, no specific treatment may be necessary, and a period of watchful waiting might be recommended. Kidney stones may require various interventions, ranging from increased fluid intake for smaller stones to surgical procedures for larger ones.
When specific kidney diseases are identified, tailored medications or management strategies will be implemented to address the condition. If a tumor or cancer is found, treatment options may include surgery, chemotherapy, radiation therapy, or a combination of these, depending on the type and stage of the cancer. The goal is to treat the cause of the bleeding.
Even after a cause has been identified and treated, or if a benign cause is determined, regular follow-up appointments are important. This monitoring ensures that the hematuria does not persist or recur, and that any underlying condition remains stable. While microscopic hematuria is often not life-threatening, continued vigilance and medical guidance are important for long-term health management.