Blood in the urine is almost always an indication of a disease of the urinary tract. A distinction can be made between visible blood (haematuria) and non-visible blood (microscopic haematuria).

Microscopic haematuria can be detected via rapid tests or microscope. A certain amount of blood in the urine is normal because this is excreted by the kidney. However, at elevated levels, it can be a sign of various diseases (e.g. kidney stones, infections, malignant tumours of the bladder, ureter and kidney, or systemic kidney disease).

In the case of gross haematuria, is important to distinguish between painful and painless haematuria. Pain with simultaneous blood in the urine often manifest in the case of infections and symptomatic kidney stones. Painless haematuria may be an indication of a malignant bladder tumour. The role of the urologist is to exclude such a tumour.

Blood thinners do not create haematuria, but they can promote it.