Medical conditions that cause hives include vasculitis, lupus and thyroid disease, according to the American Academy of Dermatology. Other medical causes of hives include bacterial infections and allergies.
Urticarial vasculitis is a disease that affects the skin and causes the small blood vessels to swell, resulting in hives, notes the Vasculitis Foundation. Doctors do not know what causes the condition in most cases, but believe that it is associated with other diseases, including systemic lupus erythematosus and Sjögren’s syndrome. Symptoms of urticarial vasculitis include fever, joint pain, swollen lymph nodes and red-rimmed hives that bleed.
Lupus is an autoimmune disease that often leads to symptoms affecting the skin, explains the Johns Hopkins Medicine Lupus Center. Hives are a common symptom of lupus sufferers, with 10 percent of patients having the symptom. The hives that lupus patients experience last more than 24 hours, and are differentiated from those caused by urticarial vasculitis by touching them to see if they turn white.
Thyroid diseases occur when the thyroid gland produces too much or too little thyroid hormone, according to WomensHealth.gov. Hypothyroidism is a disease that is caused by an inadequate amount of thyroid hormone in the body, leading to symptoms such as dry skin, fatigue and muscle weakness. Hyperthyroidism, on the other hand, occurs when the body produces too much thyroid hormone, which contributes to symptoms such as weight loss, bulging eyes and fewer menstrual periods.