The human body contains many natural polymers, such as proteins and nucleic acids. Cellulose, another natural polymer, is the main structural component of plants. Most natural polymers are condensation polymers, and in their formation from monomers water is a by-product.
Alopecia areata is one type of hair loss that typically causes patches of baldness. In some cases, total baldness develops. In many cases, the hair re-grows, typically after several months. In some cases, the hair loss is permanent.
1 Thyroid disease, anemia, protein deficiency, chemotherapy, and low vitamin levels may cause hair loss.  Alopecia areata is a form of hair loss produced by the autoimmune destruction of hair follicles in localized areas of skin.