Haematuria is one of the most common symptoms of urological disorders.
Most haematuria is caused by diseases of the urinary system, including kidney disease, ureteral disease and bladder disease, such as glomerulonephritis and IgA nephropathy, but 2% of haematuria is caused by systemic diseases or lesions in adjacent organs of the urinary system.
Therefore, the kidneys are an important part of the urinary system and renal pathology is an important factor in red urine colour.