Pilot Study: Randomized, Placebo-controlled Comparator Trial of IV vs Oral Iron Treatment of RLS With IDA. (IVOR-IDA)

Inclusion Criteria: * Diagnosis of RLS based on questionnaire and confirmed by Hopkins telephone Diagnostic Interview conducted by investigators or clinicians part of the study. * Iron deficiency anemia defined as ID either ferritin \<20 mcg/l, Tsat \<19%, anemia Hgb \<13 for both males and females. * Willingness to use contraceptive to avoid pregnancy: Women have to be surgically sterile, post-menopausal, or use one of the following contraceptives during the whole study period and after the study has ended for at least 5 times plasma biological half-life of the investigational medicinal product: intrauterine devices or hormonal contraceptives (contraceptive pills, implants, transdermal patches, hormonal vaginal devices, or injections with prolonged release). * Willingness to participate and signing the informed consent form. Exclusion Criteria: * Iron overload or disturbances in utilization of iron (e.g. haemochromatosis and haemosiderosis) * Decompensated liver cirrhosis or active hepatitis (ALAT \> 3 times upper limit of normal) * Serum ferritin \> 500 ng/mL or transferrin saturation \>40% * Active acute or chronic infections (assessed by clinical judgement that may be indicated by White Blood Cells (WBC) and C-Reactive Protein (CRP) when these are available) * Rheumatoid arthritis with symptoms or signs of active inflammation * Pregnant and nursing women * History of multiple allergies * Known hypersensitivity to parenteral or oral iron or any excipients in the drug pr…