What percentage of normal people have (microscopic) blood in the urine?
About 5-10%. Yes, alot.
Haematuria (macro- and micro-) is one of the most common urological diagnoses, leading to over 25% of urological referrals. But the prevalence of microscopic haematuria from screening healthy volunteers is approximately 5-10%; with ranges between 2.4 and 31.1%, depending on the specific population evaluated.
In other words, for many people microscopic haematuria is ‘normal’ and not a disease.
Back to haematuria in general.
The possible causes of haematuria include:
- Surgical
- Malignancy (in approximately 3% of cases)
- UTIs
- Kidney stone disease
- Benign prostatic hyperplasia (or Ca prostate)
- Other urological cancers (kidneys/bladder etc)
- Congenital or acquired anatomic abnormalities.
- Medical (nephrological, i.e. causes of CKD)
- Chronic glomerulonephritis (e.g. IgA nephropathy)
- Chronic tubulointerstital disease
- Other causes of CKD.
There is significant variability across current guidelines regarding the evaluation of microscopic haematuria, whether it should entail cystoscopy and upper tract imaging.
It is known that aside from the conflicting guidelines regarding the evaluation of microscopic hematuria, there is an overall low yield of the evaluation with malignancy diagnosed in only 3% of the cases; with less than 1% diagnosed in patients without any kind of risk factors, and more than 10% diagnosis in patients with multiple risk factors.
Additionally, the evaluation also has potential harms, which include risks to the patient and cost to the health system. Moreover, currently, there is poor adherence to the existing guidelines.
