Oval fat bodies are renal tubular epithelial cells or macrophages filled with fat globules. The nuclei of these cells are barely visible. Fat bodies are accompanied by the presence of free fat droplets and possibly by hyaline casts with fat inclusions or fatty casts. Oval fat bodies and free fat droplets (globules) in urine are considered to be an exceptional and serious finding. The presence of fat with biological origin in urine is called lipiduria and indicates severe renal dysfunction. It is associated with serious damage and necrosis of renal epithelial cells as in nephrotic syndrome, advanced diabetes mellitus or some kinds of poisoning.
Fat globules may be seen in the urine as a contamination from oiled catheter or vaginal creams. There are no fat bodies and casts in sample in this case. Examples are shown in the Artifacts category.