Occult blood in urine, also known as microscopic hematuria, refers to red blood cells in urine not visible to the naked eye. The term “occult” literally means hidden, indicating that specialized tests are required for its detection. Its presence signals a need for further investigation, as it can indicate various underlying urinary system conditions. Identifying the source is crucial for overall health.
Discovering Occult Blood in Urine
Detecting occult blood often begins with a urine dipstick test, a preliminary screening method. This test uses a reagent strip that changes color when reacting with hemoglobin, a protein in red blood cells. While convenient, dipstick tests can sometimes produce false positive results due to other substances like myoglobin or certain foods.
If a dipstick test is positive, microscopic examination of the urine, also known as urinalysis, is employed. This involves observing a urine sample under a microscope to directly count red blood cells. Microscopic hematuria is generally defined as three or more red blood cells per high-power field (HPF) in a properly collected urine specimen. This direct visualization helps confirm the presence of actual red blood cells, differentiating it from gross hematuria, where blood is visibly apparent, making the urine appear pink, red, or brown.
Common Reasons for Occult Blood
Occult blood in urine can stem from a variety of causes, ranging from common and less serious issues to more significant health concerns. Urinary tract infections (UTIs) are a frequent cause, as bacteria can inflame the urinary lining, leading to microscopic bleeding. Kidney stones, which are hard mineral deposits, can also irritate the urinary tract as they pass, causing blood to appear in the urine.
Strenuous exercise can temporarily lead to exercise-induced hematuria due to increased stress on the kidneys and bladder. Certain medications, including blood thinners, some antibiotics like penicillin, and pain relievers, may also cause or worsen microscopic bleeding in the urinary tract. In men, an enlarged prostate (benign prostatic hyperplasia or BPH) or prostate inflammation (prostatitis) can compress the urethra and lead to blood in the urine.
More serious, though less common, conditions can also manifest as occult blood. Early stages of kidney diseases, such as glomerulonephritis or polycystic kidney disease, can cause red blood cells to leak into the urine due to damage to the kidney’s filtering units or cyst rupture. Occult blood can sometimes be a sign of urinary tract cancers affecting the bladder, kidney, or prostate. Healthcare providers typically investigate the more benign causes first before considering these less common, but more serious, possibilities.
Understanding Your Results and Next Steps
A positive result for occult blood in urine is a finding that necessitates further medical evaluation, rather than an immediate diagnosis of a severe condition. It serves as an indication that something is causing red blood cells to enter the urinary tract. Consulting a healthcare professional is important for accurate interpretation of the results and guidance on appropriate follow-up actions.
The typical diagnostic pathway often begins with a detailed review of medical history and a physical examination to identify potential risk factors or accompanying symptoms. Additional tests may include a repeat urinalysis to confirm the persistence of hematuria, as transient causes like exercise or menstruation can sometimes lead to temporary findings. A urine culture may be performed to check for bacterial infections, which, if present, can often be treated with antibiotics.
If the cause remains unclear, imaging studies such as an ultrasound or CT scan of the urinary tract might be recommended to visualize the kidneys, bladder, and other structures for abnormalities like stones, cysts, or tumors. In some instances, a cystoscopy, a procedure where a thin tube with a camera is inserted into the bladder, may be performed to directly examine the bladder lining. The management plan for occult blood in urine is always tailored to the identified underlying cause, emphasizing the importance of a thorough investigation.