Red blood cells, also known as erythrocytes, are microscopic cells that carry oxygen throughout the body. While a small number of red blood cells can sometimes be present in urine, their appearance in significant amounts, especially in an altered form, can indicate underlying health conditions. “Dysmorphic red blood cells” refer to red blood cells that have an irregular or distorted shape when observed in a urine sample. Their presence is an important diagnostic finding, often pointing to issues within the kidneys.
Understanding Dysmorphic Red Blood Cells
Dysmorphic red blood cells are characterized by their unusual shapes, which can include cytoplasmic bulges, blebs, or budding projections. Some may even resemble “Mickey Mouse” cells due to symmetrical protrusions. These altered forms are identified during a microscopic examination of urine sediment, a routine part of a urinalysis.
These distorted shapes arise because red blood cells are subjected to osmotic and mechanical stress as they navigate damaged kidney structures, particularly the glomeruli. Healthy kidneys typically prevent red blood cells from entering the urine. However, when filters are compromised, these cells pass through, becoming stretched and squeezed, which leads to their characteristic dysmorphic appearance.
Common Causes
The primary reason for the presence of dysmorphic red blood cells in urine is damage to the glomeruli, which are the tiny filtering units within the kidneys. This type of bleeding from the glomeruli is known as glomerular hematuria.
Various kidney conditions can lead to glomerular damage and, consequently, dysmorphic red blood cells in the urine. One common cause is glomerulonephritis, an inflammation of the glomeruli. Specific types include IgA nephropathy, where immunoglobulin A antibodies deposit in the glomeruli, and post-streptococcal glomerulonephritis, which can occur after a streptococcal infection. Other conditions, such as Alport syndrome, a genetic disorder affecting kidney function, or lupus nephritis, a kidney inflammation associated with systemic lupus erythematosus, can also cause glomerular injury.
Why Differentiation Matters
Distinguishing between dysmorphic and non-dysmorphic red blood cells in urine is important for diagnosing the source of bleeding. Dysmorphic red blood cells suggest that the bleeding originates from the glomeruli within the kidneys.
Conversely, non-dysmorphic red blood cells, which maintain their normal, round shape, indicate bleeding from other parts of the urinary tract. This can include sources such as the bladder, ureters, or urethra. Conditions like kidney stones, urinary tract infections, or tumors in the bladder or ureters are often associated with non-dysmorphic red blood cells. Recognizing this distinction helps healthcare professionals pinpoint the bleeding’s location and guide further diagnostic investigations.
What Happens Next
When dysmorphic red blood cells are detected, further diagnostic steps determine the underlying cause. These include blood tests for kidney function (e.g., creatinine, urea) and urine protein levels, as increased protein indicates kidney damage.
Imaging studies, such as ultrasound or CT scans of the kidneys and urinary tract, visualize structures and identify abnormalities. A kidney biopsy might be considered, involving a small tissue sample for microscopic examination to determine the cause and extent of damage. Consulting a healthcare professional is important for diagnosis and to discuss the management plan.