Cloudy urine is easily observable to the human eye, and many patients go to the hospital for this reason. So, is cloudy urine pathological or not? Under what circumstances is it pathological? How does it relate to urinary tract infections? In order to clarify these questions, we may want to first understand the general composition of urine. The main component of normal human urine is water, accounting for 96% to 97%, and the solid component accounts for 3% to 4%. Normal adults excrete about 60 grams of solids every day, about 25 grams of inorganic salts in solids, half of which are sodium and chloride ions; about 35 grams of organic matter, including about 30 grams of urea, and the rest is a small amount of sugar, protein and a variety of metabolic products in the body. Normal fresh urine is transparent, urine soon after discharge will become cloudy, mainly due to the precipitation of salt crystals or bacterial growth and reproduction, placed for a longer time or higher temperatures, cloudy urine is more obvious? When fresh urine is cloudy, it can be seen in the following situations: 1. uric acid salt precipitation: after the concentrated acidic urine cools, there can be light red uric acid salt precipitation, which can be dissolved when heated or added alkali. This situation is more common in cold weather. 2, phosphate and carbonate precipitation: if the urine is alkaline, there can be phosphate or carbonate precipitation, white, add acid can be dissolved. Carbonate can produce bubbles when acid is added. 3, urinary tract infection: mainly related to the reproduction of urinary tract bacteria and the appearance of pus urine and white blood cells. The urine is milky white. 4, celiac disease: white celiac-like urine, seen in filariasis or other causes of perirenal lymphatic obstruction. This is easy to identify under the naked eye. Of the above four conditions, the first two are generally not lesions. If crystals such as uric acid and phosphate precipitate frequently in fresh urine with a high number of red blood cells, the possibility of urinary stones should be suspected. In urinary tract infections, cloudy urine is seen, and pus cells or white blood cells can be found on microscopic examination of urine sediment. As for patients with nephritis with predominantly urinary protein, fresh urine is usually not cloudy.