Restless legs syndrome can be a secondary problem caused by another condition. Researchers continue their efforts to understand and define the relationship between this syndrome and:

• Iron deficiency or related anemia. The way the body metabolizes iron and certain proteins in the brain may be related to restless legs syndrome.
• Pregnancy. Approximately 20% of pregnant women develop restless legs syndrome, which often goes away without treatment shortly after the child is born. Women who have it before they become pregnant may develop more noticeable and frequent symptoms during pregnancy.
• Kidney disease.
• Diabetes.
• Neurological diseases, including peripheral neuropathy, Parkinson's disease, and possibly radiculopathy (a pinched nerve), which is a disorder of the spinal nerve roots.

When you are diagnosed with restless legs syndrome, you may also be tested for one of these conditions if your symptoms suggest a specific cause. Your doctor may recommend one or more of the following tests:

• Blood tests, such as a complete blood count, iron (ferritin) levels, or chemistry screen. The results from these tests may help determine whether symptoms are related to anemia, low blood iron levels, kidney problems, or diabetes.
• Electromyogram and a nerve conduction study, if symptoms suggest that nerves are damaged.