Red blood cells (RBCs) are components of the blood that carry oxygen throughout the body. Their presence in urine, a condition known as hematuria, indicates blood in the urinary tract. While sometimes visible to the naked eye, blood in urine can also be microscopic and undetectable without testing. This article will clarify what constitutes an elevated amount of red blood cells in urine and what this finding might signify.
Understanding Red Blood Cells in Urine
Red blood cells typically remain within the circulatory system. Healthy kidneys filter waste products from the blood to form urine without allowing red blood cells to pass through. Therefore, finding red blood cells in urine generally indicates an issue within the urinary system, which includes the kidneys, ureters, bladder, and urethra.
Hematuria can manifest in two forms: gross hematuria and microscopic hematuria. Gross hematuria is when blood in the urine is visible, often appearing pink, red, or cola-colored. Microscopic hematuria, conversely, means the blood is only detectable under a microscope during a urinalysis. Even microscopic amounts of red blood cells warrant investigation, as they can indicate underlying conditions that require attention.
Defining High Levels of RBCs
The presence of red blood cells in urine is typically measured during a urinalysis. This measurement is often expressed as the number of red blood cells per high power field (RBCs/HPF) when examined under a microscope. A generally accepted threshold for an elevated red blood cell count in urine is more than 2 to 3 RBCs/HPF.
While some laboratories may define “high” slightly differently, consistently finding more than a few red blood cells per high power field is considered abnormal. Even small increases can be significant because the urinary tract should ideally be free of red blood cells. A single instance of a slightly elevated count might not be as concerning as repeated findings of increased RBCs, which often prompt further medical evaluation.
Potential Reasons for Elevated RBCs
Several conditions can lead to an elevated red blood cell count in urine, affecting different parts of the urinary system. Urinary tract infections (UTIs) are a common cause, where bacteria irritate and inflame the urinary tract lining, causing blood to appear in the urine. Kidney stones, hard deposits that form in the kidneys, can also cause bleeding as they pass through or obstruct the urinary tract, irritating the lining.
Various kidney diseases, such as glomerulonephritis (inflammation of the kidney’s filtering units) or pyelonephritis (kidney infection), can damage the tiny filtering units of the kidneys, allowing red blood cells to leak into the urine. Certain cancers of the bladder or kidneys may also cause hematuria, as tumors can cause bleeding within the urinary system. In men, prostate issues like an enlarged prostate (benign prostatic hyperplasia) or prostate cancer can also cause hematuria.
Less common causes include strenuous exercise, which can temporarily cause microscopic hematuria, and certain medications, such as blood thinners, that increase the risk of bleeding. Trauma or injury to the kidneys or urinary tract can also result in blood in the urine.
Next Steps After a High RBC Result
Discovering an elevated red blood cell count in urine necessitates a consultation with a healthcare professional. Self-diagnosis or delaying medical evaluation is not advised, as the underlying cause could range from a minor infection to a more serious condition. A doctor will typically begin by reviewing a patient’s medical history and conducting a physical examination.
Further diagnostic procedures may include:
Additional urinalysis tests to confirm the presence of red blood cells.
Urine culture to check for bacterial infections.
Imaging tests, such as an ultrasound or CT scan of the abdomen and pelvis, to visualize urinary structures for abnormalities like stones or tumors.
Cystoscopy, which involves inserting a thin, lighted tube with a camera into the urethra to examine the bladder and urethra, to directly inspect the urinary tract lining.