Hematuria is a health condition that is characterized by the presence of blood in the urine. There are two main types of hematuria that are known as microscopic and macroscopic hematuria. Hematuria can also be classified according to the cause of the blood in the urine.
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In microscopic hematuria, there is no visual evidence of the presence of blood, unless the urine is viewed under a microscope. Comparatively, macroscopic hematuria is evident immediately with red discoloration of the urine.
The concentration of blood in the urine is not visible to the naked eye in microscopic hematuria and can only be detected under a microscope.
Some individuals are affected by microscopic hematuria without an identifiable cause, which is referred to as idiopathic hematuria. This is thought to result from an increased excretion of red blood cells (RBCs) in respect to what is considered to be normal, although the condition may not be associated with adverse effects on the individual.
Also known as frank or gross hematuria, macroscopic hematuria involves visible discoloration of the urine as a result of a greater concentration of blood in the urine. The color of the urine is usually described as pink, red, or dark brown. Additionally, there may also be evidence of small or large blood clots in some cases.
It is not necessary for a large volume of blood to be present for the color of the urine to be altered. In fact, 1 milliliter (mL) of blood is sufficient to precipitate a change in color. Additionally, the volume of blood may not be an accurate indicator of the severity of the underlying cause, and even a small quantity of blood may have serious repercussions and vice versa.
“Joggers hematuria” is a specific type of hematuria that occurs as a result of recurrent damage to the bladder during activities such as jogging and long-distance running.
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Classification by cause
Hematuria can also be classified according to the cause of the condition, as follows:
- Infective hematuria: This form of hematuria arises due to pyelonephritis, cystitis, or urethritis.
- Stones-related hematuria: This form of hematuria arises due to staghorn calculi, calcium stones, or uric acid stones.
- Trauma-related hematuria: This condition occurs due to pelvic trauma, renal injuries, or foreign bodies.
- Renal hematuria: Renal hematuria can occur as a result of IgA nephropathy, hereditary nephritis, medullary sponge kidney, or thin basement membrane diseases.
- Iatrogenic hematuria: This form of hematuria is due to a recent endoscopic procedure, trans-rectal ultrasound, traumatic catheterization, radiation, indwelling ureteric stents, renal biopsy, or extracorporeal shockwave lithotripsy.
- Benign hematuria: Benign hematuria can be due to strictures, renal masses, or benign prostatic hypertrophy.
- Malignant hematuria: This form of hematuria is due to prostate acinar adenocarcinoma or renal cell, transitional cell, squamous cell, or urothelial cell carcinoma.
Other causes of red discoloration
While red discoloration is the most distinctive feature of hematuria, there are various other causes that can lead to this discoloration of urine. These may include the presence of pigments such as:
- Myoglobin (indicative of myoglobinuria)
- Porphyrins (indicative of porphyria)
- Betanin (in beets)
Additionally, some drugs can have a similar effect on the body, including rifampicin, phenazopyridine, sulphonamides, and nonsteroidal anti-inflammatory drugs (NSAIDs).