Haematuria (blood in the urine)
Haematuria means blood in the urine. If it is ‘microscopic’, this means something is so small that it can only be seen through a microscope. So, if you have microscopic haematuria, you have red blood cells in your urine that cannot be seen with the naked eye.
In microscopic haematuria the urine looks normal. In macroscopic (or ‘gross’) haematuria, the urine is red as there is a larger amount of blood in it. The two types of haematuria have different causes. This article is about microscopic haematuria.
How common is microscopic haematuria?
Very. In fact in some studies, 10% of the population have it. When a thing is so common, it is important to question whether it is a disease. In other words, microscopic haematuria could be a normal variant (i.e. normal). But there are some serious causes as well (see below). Or it could be so common as some of the causes are very common, e.g. benign enlargement of the prostate in men.
Note. All of this is why doctors find it hard to know whether to investigate it or not.
Symptoms of microscopic haematuria
Most of the time, you will not have symptoms of microscopic haematuria.
What causes microscopic haematuria?
For many, there is no cause for microscopic haematuria. It comes and goes on its own. Other times, it may be caused by:
- UTI
- Benign prostatic hypertrophy (BPH) – benign enlargement of the prostate in men
- Urinary tract infection (UTI)
- ‘Glomerulonephritis’, which is a long-term autoimmune inflammation of the kidneys – especially one called IgA nephropathy
- Kidney or bladder stone
- Polycystic kidney disease
- Some medicines
- Blood diseases, like sickle cell anaemia
- Tumour in the urinary tract (may or may not be cancer)
- Rare diseases like thin membrane disease.
Note. Some of these causes will have more specific symptoms related to that disease (e.g. loin/back pain in a kidney stone) or no symptoms of that cause.
How is microscopic haematuria diagnosed?
Your doctor will ask you for a urine sample. They will test your urine with a dipstick (urinalysis) for the presence of red blood cells. Your doctor will also check for other things that might explain what’s wrong. For example, white blood cells in your urine usually means you have an infection. If you do have blood in your urine, your doctor will ask you some more questions to find out what caused it.
If the cause is not clear, you may need more tests, including:
- Mid-stream sample of urine (MSU) – as part of this, the urine is microscoped and if you have microscopic haematuria, more blood than normal is seen. This is how the diagnosis is made
- Blood tests, including a full blood count (‘FBC’), and ‘U+Es’ (test of kidney function including creatinine and eGFR)
- Ultrasound, or
- Cystoscopy. This is done using a special tool called a cystoscope, which is used to look inside your bladder. This type of test is done by a hospital-based kidney surgeon called a urologist. Not all people need a cystoscopy
- Renal (kidney) biopsy. This is very rarely needed.
Summary
We have described microscopic haematuria (blood in the urine). We hope it has been helpful.
Other resource
There is more information about haematuria (blood in the urine) written by the renal team at UCHW Coventry.
Last Reviewed on 14 November 2023