Precipitation of salts in the urine means the transition from the soluble state to the insoluble condition. Usually, this cloudy urine is harmless phenomenon which is caused by salts (crystals) that are insoluble in the cooling urine and therefore precipitate (whitish to pinkish cloudy urine).
The salts of uric acid in urine can vary and cause cloudy urine. After cooling, in the fresh acidic urine (usually at a pH below 6), there are light-red urates precipitated. So, urine looks cloudy, mucus threads, light red in color/ or yellow-brown with a light shade of red.
Because of the reddish hue, this urine is then called brick dust urine. If in this case cloudy urine is tinged with dark red, it needs to be distinguished from blood in urine.
The salts of phosphoric acid in the urine can be precipitated and make urine cloudy. The sediment in this case is white.
Phosphates occur more easily in the less acidic or alkaline urine (pH>6). Additional Info: Diet with vegetables or rich fruit increases the urinary pH; even with urinary tract infections, the pH is usually high.