Finding red blood cells in urine, medically known as hematuria, can be concerning. While it often prompts immediate worry, it does not always signify a severe underlying condition. However, hematuria is a symptom that warrants medical evaluation to determine its cause. Understanding its potential origins can help individuals approach this finding with informed awareness.
Defining Red Blood Cells in Urine
Hematuria is the presence of red blood cells (RBCs) in urine, broadly categorized into two types: gross and microscopic. Gross hematuria is visible to the naked eye, causing the urine to appear pink, red, or cola-colored. Even a small amount of blood, as little as 1 milliliter per liter of urine, can cause a noticeable color change.
Microscopic hematuria, conversely, is not visible to the naked eye. It is detected through laboratory analysis, typically when a urine sample is examined under a microscope. Healthy urine contains a very low count of red blood cells, generally less than 3 RBCs per high-power field (HPF). A higher count indicates microscopic hematuria.
Common Causes of Red Blood Cells in Urine
Red blood cells in urine can stem from various sources within the urinary tract, including the kidneys, ureters, bladder, and urethra. Urinary tract infections (UTIs) are a frequent cause, as bacteria can lead to inflammation and bleeding. UTIs often present with symptoms like painful or frequent urination.
Kidney stones or bladder stones, hard mineral deposits, can also cause hematuria as they move through the urinary tract, irritating or damaging tissues. Kidney diseases, particularly those affecting the glomeruli—the tiny filtering units—can result in blood leaking into the urine. Glomerulonephritis, an inflammation of these filters, is one such condition.
In men, an enlarged prostate, common with aging, can compress the urethra and lead to blood in the urine. Certain medications, especially blood thinners like warfarin or rivaroxaban, can increase the risk of hematuria due to their anticoagulant effects. Other drugs, including specific antibiotics or pain relievers, may also contribute.
Strenuous physical activity, often termed “exercise-induced hematuria,” can cause temporary bleeding in the urine, particularly in long-distance runners. This usually resolves within 24 to 72 hours following the activity. Less commonly, but more significantly, blood in the urine can be a symptom of kidney or bladder cancer, especially in individuals over 50 or those with a smoking history. Contamination from menstrual blood in women can also lead to a false positive for hematuria during a urine test.
Detection and Diagnostic Process
When red blood cells are suspected in urine, healthcare providers typically begin with a urinalysis. This involves a dipstick test, where a chemical strip changes color if blood is present, followed by a microscopic examination of the urine. Microscopic analysis allows for counting red blood cells per high-power field (HPF) and observing their shape, which can offer clues about the bleeding source.
If hematuria is confirmed, additional diagnostic tests are often necessary to pinpoint the underlying cause. A urine culture may be performed to check for a urinary tract infection. Imaging studies, such as an ultrasound or CT scan of the urinary system, can help visualize the kidneys, bladder, and ureters to identify abnormalities like stones, tumors, or structural issues. For evaluating the bladder and urethra, a cystoscopy might be recommended. This procedure involves inserting a thin tube with a camera to directly examine the internal lining.
When to Seek Medical Attention
Any visible blood in the urine, even if it appears only once, warrants prompt medical evaluation. While some causes are benign and temporary, self-diagnosis is not recommended. Microscopic hematuria, though not visible, also requires investigation, especially if it persists or is found in individuals over 35.
Consulting a healthcare provider allows for a thorough assessment, including a review of medical history and a physical examination. Timely diagnosis is important because certain conditions, such as urinary tract cancers, are more effectively treated when detected early. A doctor can determine the specific cause and recommend appropriate management or treatment.