This is due to the fact that celiac fluid (fatty saponified fluid) absorbed from the intestine cannot be drained from the normal lymphatic vessels into the bloodstream and can only flow backwards into the lymphatic vessels of the urinary system, resulting in increased pressure in the lymphatic vessels of the urinary system and the rupture of the lymphatic vessel varices causing the celiac fluid to overflow into the urine.
In addition to this, some purulent infections causing pus urine or environmental lifestyle factors causing crystalluria can also cause a milky white urine.