Correlation between systemic iron parameters and substantia nigra iron stores in restless legs syndrome.

OBJECTIVE: To evaluate the relation between systemic iron parameters (SIP) and substantia nigra (SN) iron deposits, as assessed by transcranial sonography (TCS) in restless legs syndrome (RLS). METHODS: We conducted a cross-sectional study in RLS patients, from whom blood samples with SIP were obtained, consisting of total iron-binding capacity (TIBC), serum ferritin, hemoglobin, transferrin saturation (TSAT), serum iron, and serum transferrin. TCS was performed over the SN, and the substantia nigra echogenicity index (SNEI) was determined according to established methods. Symptom severity was evaluated using the international restless legs scale (IRLS). A Spearman correlation was performed. RESULTS: A total of 167 patients were studied. Correlations between SNEI and SIP were as follows: serum ferritin (R = 0.0422; n.s.), TSAT (R = 0.0883; n.s.), TIBC (R = -0.1091; n.s.), serum transferrin (R = -0.0420; n.s.), hemoglobin (R = 0.0185; n.s.), serum iron (R = 0.0389; n.s.). No correlation was found with age and IRLS (R = 0.1375; n.s. and R = 0.0880, n.s., respectively). CONCLUSIONS: SIP are not correlated with SN iron content in RLS, quantified by means of TCS. TCS of the SN might be a more valid estimate and could be useful in the evaluation of RLS patients.

Low risk of iron overload or anaphylaxis during treatment of restless legs syndrome with intravenous iron: a consecutive case series in a regular clinical setting.

OBJECTIVE: To evaluate the incidence of iron overload and anaphylaxis following intravenous (IV) iron treatment of restless legs syndrome (RLS). METHODS: A total of 58 consecutive RLS patients, meeting clinical requirements for IV iron treatment according to current IRLSSG guidelines were recruited. IV iron treatment consisted of two 500 mg infusions of ferric carboxymaltose (FCM) administered five days apart. During each of the three follow-up visits we obtained blood samples, substantia nigra echogenity index (SNEI) by means of transcranial sonography (TCS), and assessed the severity of RLS symptoms (IRLS scale). "Iron overload risk" was defined as transferrin saturation (TSAT) > 45% on two consecutive follow-up visits. In patients who had a reduction in systemic iron levels following treatment, an additional 500 mg of FCM was administered when feasible. In such cases an additional two follow-up visits were performed. RESULTS: Among the total sample, only 2/58 participants met criteria for iron overload risk. They had no evidence of liver damage and did not require additional treatment. Among the 21 patients receiving an additional 500 mg infusion after, only one patient was diagnosed with iron overload risk. Among these three patients, only one was a hemochromatosis gene carrier. No anaphylaxis or other side-effects were reported. CONCLUSIONS: In real-life clinical conditions, the risk of iron overload is low when IV FCM is administered according to the safety limits defined in the current RLS treatment guidelines. However, a close clinical follow-up with periodic blood sampling for iron status, is needed.