From the Guidelines
For patients with Restless Legs Syndrome (RLS), a ferritin level of 75 ng/mL or less is considered low enough to potentially contribute to symptoms, and supplementation may be recommended. According to the American Academy of Sleep Medicine clinical practice guideline 1, serum ferritin levels should be regularly tested in patients with clinically significant RLS, and iron supplementation should be instituted if serum ferritin is ≤ 75 ng/mL or transferrin saturation is < 20%. Some key points to consider in the management of RLS include:
- Testing for serum iron studies, including ferritin and transferrin saturation, should be done in the morning, avoiding iron-containing supplements and foods for at least 24 hours prior to the blood draw 1
- Iron supplementation guidelines for RLS differ from those for the general population, with a focus on achieving higher ferritin levels to manage symptoms 1
- The first step in managing RLS should be addressing exacerbating factors, such as alcohol, caffeine, and certain medications 1
- Regular monitoring of ferritin levels is necessary during supplementation, and treatment should continue until levels exceed 100 ng/mL or symptoms resolve. It's also worth noting that, in children, supplementation of iron should be instituted for serum ferritin < 50 ng/mL with oral or IV formulations 1.
From the Research
Ferritin Range for RLS
- The ideal ferritin range for Restless Legs Syndrome (RLS) treatment is not explicitly stated in the provided studies, but several studies suggest that low-normal ferritin levels may benefit from oral iron replacement 2.
- A study found that symptomatic RLS patients with low-normal serum ferritin levels (baseline ferritin levels of 40.6+/-15.3ng/ml and 36.7+/-20.8ng/ml) benefited from oral iron replacement, with a significant decrease in International Restless Leg Scale (IRLS) scores 2.
- Another study reported a median baseline ferritin level of 22.7 ng/mL, with 71% of children having a ferritin level less than 30 ng/mL, and found that supplemental iron was effective in treating pediatric RLS 3.
- The use of low serum ferritin levels as an inclusion criterion did not show significant subgroup differences in the response to iron therapy 4.
Iron Supplementation and RLS
- Iron supplementation is associated with a significant decrease in IRLS scores and an increase in the percentage of patients with improvement of the IRLS score 5.
- Iron therapy probably improves restlessness and RLS severity in comparison to placebo, and may not increase the risk of side effects in comparison to placebo 4.
- The optimal timing and formulation of iron administration, as well as patient characteristics predicting response, require additional study 4.