There is an endless list of medical conditions that can cause hair loss. We are going to look at some of the medical conditions causing hair loss. The most common medical conditions that affect hair loss are those that change the integrity of the skin. A good example which has become common is HIV and AIDS. HIV is a virus that causes AIDS which is a weakening of the body's immune system. When the body no longer has an immune system it cannot defend itself from pathogens and other foreign invaders. These pathogens find easy entrance to the body due to the weakened immune system. Fungal and bacterial diseases are common amongst persons with AIDS. These fungal diseases then affect the skin causing hair follicles to dilate and collect puss. When the pimples full of pass burst they live behind scared tissue which has no hair growth. In time, those parts of the skin are left with no hair growth.

There are other conditions that result in hair loss. Examples include sugar diabetes, cancer and some thyroid disorders. Sugar diabetes affect the body's immune system and the condition of hair loss may occur much in the same way as described above. Cancer is a very serious disease that can cause serious hair loss. There are different kinds of cancer. The most serious one that can cause serious hair loss is skin cancer. The skin will be containing mutated cells. These cells will divide uncontrollably. The problem is that these cells will be abnormal and they will not have all the cellular functions that are typical of cells in their region. If these cells are on the scalp it will result in patches on the scalp. What usually happens is that the body tries to destroy the mutated cancerous cell, but in the event of doing so it will also destroy features such as hair in the process. Cancer also weakens the skins defensive mechanism making it become more vulnerable to other skin infections that will result in hair loss.

In the case of thyroid malfunctions caused by physical damage or inherited gene mutations, hair loss is another common feature. The thyroid is involved in releasing a lot of hormones that are associated with cellular function. If the thyroid is damaged or contains some mutated genes it can either release few hormones, no hormones or too many hormones. All these situations are not desirable and they all cause situations like hair loss. In the case of low hormone secretion by the thyroid, hair follicles will not receive any signals to produce compounds such as keratin which affects hair growth. In the case of increased secretion of hormones, certain hormones such as the androgens, when in high concentrations, will cause hair thinning in females and male pattern baldness in males. It is good to realize that any disease that affects the immune system can result in hair loss. Most medical conditions do alter the body's chemical constituency and affect the immune system, that is why symptoms such as hair loss are common in many disease conditions.