In what kind of urine will red blood cells appear as ghost cells?

Red blood cells appearing as ghost cells is indicative of hemolysis that occurs in dilute urine. This situation typically arises in hyposthenuric urine, which is characterized by a low specific gravity. When urine has a low specific gravity, it is less concentrated, resulting in a higher water content. When red blood cells are exposed to such dilute solutions, they can swell and eventually burst, leading to hemolysis. The remnants of these lysed red blood cells are seen under the microscope as ghost cells—transparent shells with little to no hemoglobin visible.

In contrast, isosthenuric and hypersthenuric urines have a balanced or high concentration of solutes, respectively; in these conditions, red blood cells generally maintain their shape and integrity, thus not leading to the appearance of ghost cells. Normal urine, which typically falls within the isosthenuric range, would also not show this phenomenon under normal conditions.