When a laboratory report indicates “lysed blood in urine,” it means that red blood cells have ruptured within the urinary system, releasing their internal contents. The primary content released is hemoglobin, an oxygen-carrying protein. This finding, also known as hemoglobinuria, suggests blood components are present, but whole red blood cells may not be visible under a microscope. This condition often does not cause a visible change in urine color, especially if the amount is small.
Understanding Hemoglobinuria and Hematuria
Distinguishing between hemoglobinuria and hematuria is important for understanding laboratory results. Hematuria signifies the presence of intact, whole red blood cells in the urine. One might think of hematuria as finding whole grapes in a bowl, representing the complete cells. In contrast, hemoglobinuria, or lysed blood, means that the red blood cells have broken apart, and only their internal hemoglobin is present in the urine. This is comparable to having only grape juice in the bowl, where the original grape (red blood cell) is no longer whole.
Hematuria often points to bleeding occurring anywhere along the urinary tract, from the kidneys to the urethra. The red blood cells remain intact as they pass through the urinary system. Hemoglobinuria, however, implies that red blood cells have lysed, either within the bloodstream before reaching the kidneys or within the urine itself after excretion. This cellular difference helps medical professionals narrow down the potential causes behind the unusual finding in a urine sample.
Potential Causes of Lysed Blood in Urine
Lysed blood in urine can stem from several underlying conditions or external factors that cause red blood cells to break down. Strenuous physical activity, such as long-distance running, is a common and often less severe cause, leading to temporary red blood cell breakdown. Minor urinary tract infections (UTIs) can also contribute, as bacteria and inflammation may cause red blood cells to lyse. Improper handling or storage of a urine sample can also cause red blood cells to lyse, particularly if the urine is very alkaline.
Certain medical conditions are associated with hemoglobinuria due to increased red blood cell destruction. Kidney diseases, such as acute glomerulonephritis, can sometimes lead to this finding. Autoimmune disorders, such as autoimmune hemolytic anemia, where the immune system attacks red blood cells, can also result in widespread lysis. Genetic conditions, including sickle cell anemia and glucose-6-phosphate dehydrogenase (G6PD) deficiency, predispose red blood cells to premature breakdown, releasing hemoglobin that is then filtered by the kidneys.
External factors can also induce red blood cell lysis. Severe burns can cause extensive red blood cell damage, leading to hemoglobin release. Certain medications, including some antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDs), have been linked to increased red blood cell breakdown. A severe transfusion reaction, occurring when a patient receives incompatible blood, triggers rapid, widespread red blood cell destruction, releasing significant hemoglobin into circulation.
How Doctors Determine the Cause
Lysed blood in urine is a laboratory finding that prompts further investigation, rather than being a diagnosis. Healthcare providers begin by taking a detailed medical history and conducting a physical examination to gather clues about underlying conditions. This initial assessment helps in understanding any symptoms and relevant past medical issues.
The diagnostic process often includes repeating urinalysis to confirm hemoglobin presence and performing urine microscopy. Microscopy allows the doctor to check for the absence of intact red blood cells, which, if present, would indicate hematuria instead of hemoglobinuria.
Blood tests are commonly ordered to assess kidney function, measure hemoglobin levels, and look for markers of inflammation or conditions like hemolytic anemia. Specific blood tests, such as a haptoglobin test or lactate dehydrogenase (LDH) levels, can indicate increased red blood cell destruction. Imaging tests like an ultrasound of the kidneys and bladder may also be performed to visualize the urinary tract and rule out structural issues or kidney stones. The goal of this thorough evaluation is to pinpoint the exact cause for appropriate and targeted treatment.