Yeast is a fungus often caused in humans by Candida Albicans. This yeast is normally present in small amounts in the body. However, overgrowth can occur when the balance between the yeast and healthy bacteria is disturbed, such as by antibiotics, a weakened immune system or diabetes.

Under the microscope, yeast is often recognized by its typical yeast straightening (roundish cells) and fungal threads (hyphae), which look like thin thread-like structures. Yeast cells may appear in clusters or chains, depending on the type of infection. Precise differentiation based on urine is often not possible.