Peripheral neuropathy: This damage to the nerves in your hands and feet is sometimes due to chronic diseases such as diabetes and alcoholism.
Iron deficiency: Even without anemia, iron deficiency can cause or worsen RLS. If you have a history of bleeding from your stomach or bowels, experience heavy menstrual periods, or repeatedly donate blood, you may have iron deficiency.
Kidney failure: If you have kidney failure, you may also have iron deficiency, often with anemia. When kidneys don't function properly, iron stores in your blood can decrease. This and other changes in body chemistry may cause or worsen RLS.
Spinal cord conditions: Lesions on the spinal cord as a result of damage or injury have been linked to RLS. Having had anesthesia to the spinal cord, such as a spinal block, also increases the risk of developing RLS.
Complications:
Although RLS doesn't lead to other serious conditions, symptoms can range from barely bothersome to incapacitating. Many people with RLS find it difficult to fall or stay asleep. Severe RLS can cause marked impairment in life quality and can result in depression. Insomnia may lead to excessive daytime drowsiness, but RLS may interfere with napping.
Courtesy: Mayo Clinic