What Is Hematuria?
Hematuria is the presence of red blood cells in the urine.
Hematuria can be either:
- Microscopic – not visible to the naked eye
- Macroscopic – visible to the naked eye
Microscopic hematuria occurs in 2-5% of people in the community. It can be normal to lose red blood cells in the urine, but not enough to show up in tests. Microscopic hematuria is defined as when a urine sample is seen under a microscope there are more than 3 red blood cells per high power field view in 2 out of 3 urine specimens.
This occurs when there is more than 1ml of blood in urine. However, not all red coloured urine is due to blood. Urine can also appear red:
- After eating beetroot due to its pigment
- With medications (eg: rifampicin)
- With filtered breakdown products of muscle
Causes Of Hematuria
There are many possible causes of hematuria ranging from the trivial to the lethal. Some of the more common causes include:
- Urinary tract infection – normally in this case there is pain with urinating along with the blood in the urine.
- Stones – in the kidney or bladder
- Benign prostatic hyperplasia
- Cancers of the kidney, prostate or bladder
- Vigorous exercise
- Idiopathic (no cause found)
Regardless of the type of hematuria, persistent hematuria requires investigation in order to exclude any possible serious underlying causes such as cancer.
About 20% of patients with macroscopic hematuria have underlying cancer as the cause. Tests performed are:
- Imaging with a CT IVP. This is where X-ray dye is injected into the veins. The dye is then taken up by the kidneys and excreted into the ureters. As a result any abnormality of the kidneys or ureters is readily seen.
- Cystoscopy is done to assess for any possible bladder problems.
About 2 to 3% of patients with microscopic hematuria have underlying cancer as the cause. While CT IVP can be done in this setting an alternative is:
- Imaging with ultrasound of the kidneys to check for any causes.
- Urine cytology. This is where the urine is tested for any cancer cells shed by a possible underlying cancer. However, urine cytology is not very sensitive for low grade cancers. As such a negative result does not mean that cancer is not present.
- Cystoscopy – is required to assess the bladder.
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Treatment depends on cause identified and if a cause is found it is dealt with appropriately. If no cause is found further treatment is not required.