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The mystery of hematuria: Why does urine turn red or brown?
Hematuria, the presence of blood or red blood cells in the urine, can be a cause for concern, whether it is visible blood or tiny red blood cells. When urine appears red, brown, or tea-colored, it is called "overt hematuria." Sometimes, microscopic blood in the urine may be detected through a microscope or laboratory tests. This condition can be caused by any part of the urinary system, including the kidneys, ureters, bladder, urethra, and even in the case of men, the prostate gland.
"Hematuria can have many causes, including urinary tract infection (UTI), kidney stones, viral illness, trauma, bladder cancer, and strenuous exercise."
The causes of hematuria are generally divided into two categories: glomerular and non-glomerular, depending on which glomeruli are affected. But not all red urine means hematuria. Certain medications and foods (such as blackberries, beets, and food dyes) may also make your urine appear red. A woman's menstrual period can also cause the appearance of hematuria and may make the urine test positive. Urine tests may also give false positive results if they encounter other urine components, such as the presence of myoglobin, a protein that is excreted into the urine during rhabdomyolysis. The most accurate way to confirm hematuria is by microscopic examination, defined as the presence of three or more red blood cells per high-power field.
Differential Diagnosis
Hematuria can be classified by its visibility, anatomical source, and the timing of bleeding during urination. Visible blood in the urine (called "gross hematuria") may be red or brown, or microscopic hematuria (not visible but detectable with a microscope or tests). Blood or red blood cells may enter the urine at various anatomical sites, including the kidneys, ureters, bladder, urethra, and, in men, the prostate.
"Based on the anatomical origin, the sources of hematuria can usually be divided into glomerular and non-glomerular."
Glomerular hematuria usually presents as deformed red blood cells or red blood cell casts, which are formed because red blood cells are deformed when passing through the glomerular capillaries. This is indeed a pathological process and certain conditions, such as IgA nephropathy, hereditary nephritis or minimal change disease, can lead to this condition.
Causes of Non-Glomerular Hematuria
The presence of obvious blood clots in the urine usually indicates non-glomerular hematuria. Common causes include urinary tract infection, kidney stones, cancer (such as renal cell carcinoma and bladder cancer), and even others such as bladder injury or strenuous exercise. Certain people have bleeding tendencies, such as anemia or vitamin K deficiency, or some medications (such as blood thinners) may also increase the risk of bleeding.
Hematuria Imitator
Not all red or brown urine is caused by hematuria. Certain medications and foods such as beets can also make urine appear red. For example, hydrochloric acid drugs and drug-induced chromaturia are both cause for concern. Additionally, urine tests may give false positive results due to other substances in the urine. Although urine testing can identify red blood cells, it may also identify free hemoglobin, usually due to hemolysis or myolysis.
Hematuria in Children
In children, common causes of hematuria include fever, strenuous exercise, acute nephritis, and congenital anomalies. Some conditions, such as urethral injury or mechanical trauma (such as masturbation), may also cause hematuria.
Evaluation and Inspection
The evaluation of hematuria depends on the visibility of blood in the urine (gross or microhematuria). Significant hematuria must be investigated further as it may have a pathological cause. In patients with significant hematuria, there is a 20 to 25% chance of finding urinary tract cancer.
"If the initial evaluation does not reveal a cause, further evaluation by a urologist is warranted."
After confirming hematuria, the next step is to rule out benign causes, such as urinary tract infection and recent trauma or surgery. There are separate steps in evaluating glomerular and non-glomerular hematuria, and treatment is based on the cause.
However, when no clear cause can be found, how to continue to pay attention to the patient's health will test the judgment of medical workers. Are you ready to tackle these potential health challenges?
