Red blood cells in urine is the cause of blood in urine, that can be divided into microscopic blood in urine and macroscopic bloody urine.
Microscopic blood in urine:
That means there are red blood cells in urine, but the blood cannot been seen by just the naked eye. Usually this urine is normal in urine color and transparency, not a cloudy urine. That is because of too small amounts of blood to change the urine.
Macroscopic blood in urine:
Plentiful red blood cells in urine will change the color and transparency of urine, and result in red cloudy urine. This type of blood in urine is visible grossly with just the naked eye.
Red blood cells in urine is a common abnormal change and there are many causes can cause it. Urinary tract tumor, inflammation and stones are the three most common causes.
Other causes include polycystic kidney disease, trauma, thrombocytopenia purpura, hemophilia, or hypertension, diabetes, anemia and leukemia.
Red cloudy urine
Red cloudy urine is a result of macroscopic blood in urine. The color of urine is red or red-brown.
If the presence of red blood cells in urine is caused by bladder cancer, renal pelvis cancer, renal cell carcinoma (kidney cancer) or glomerular kidney disease (mainly glomerulonephritis), you may experience a symptom of blood in urine no pain. Otherwise, you will feel a pain during/after urination.
It must be pointed out that: There is no necessary relationship between the number of red blood cells in the urine and the severity of diseases. The more severe the damage caused by diseases, the more red blood cells in urine, but the inflammation, stones and other non-cancer diseases can be cured. However, cancer is deadly even if it may cause a small amount of, or microscopic blood in urine.