MODEL RELEASED. Urine sample. Man holding an empty urine sample tube that was given to him by the general practice (GP) nurse. The man is expected to produce a urine sample in the toilet (door seen in background). The sample will undergo routine tests known as urinalysis. Physical examinations test the sample's colour, concentration and cloudiness. Kidney or urinary tract disorders may be shown by the presence of blood cells in the urine when looked at with a microscope. Culture tests of urine can be used to detect urinary infections. A range of chemical tests can reveal other disorders. For example, excessive glucose in the urine usually indicates diabetes mellitus.