Serum Ferritin Levels in Parkinson's Disease Patients with and without Restless Legs Syndrome

Abstract

Background: The frequency of RLS in Parkinson's disease (PD) patients has been reported to be between 10% and 26%. Several hypotheses have sought to link these two diseases; however, the pathophysiology of RLS in PD patients has yet to be completely defined. Many patients with idiopathic RLS have low serum ferritin levels, which negatively influence RLS symptomatology. Our objective was to investigate the role of iron deficiency in PD patients with and without RLS. Methods: We consecutively included 42 PD inpatients undergoing pharmacological treatment. Patients with anemia, renal insufficiency, or polyneuropathy were excluded from the study. The control group consisted of 42 PD inpatients without RLS (PD-nonRLS), matched for age and severity of PD. RLS was diagnosed clinically according to diagnostic criteria. Serum ferritin levels were measured at admission for all patients. Results: Mean serum ferritin values were 142.20 AE 91.17 ng/dL for PD patients with RLS (PD+RLS) and 160.65 AE 142.57 ng/dL in PD-nonRLS (P = 0.704). There was no difference concerning the total dopaminergic dose (levodopa equivalent dose) between PD+RLS and PD-nonRLS patients (828.22 AE 389.02 vs. 775.32 AE 324.69 mg; P = 0.501). The frequency of dopamine agonist (DA) use did not differ between the two groups (P = 0.306). Conclusions: There were no significant differences in serum ferritin levels between PD+RLS and PD-nonRLS in our study. This suggests a different pathophysiology of RLS in PD patients, where iron deficiency is not necessarily observed. DA use was not found to be associated with the occurrence of RLS symptoms.The relationship between RLS and Parkinson's disease (PD) is controversial. Some studies have shown a higher prevalence of RLS in PD patients, compared to controls, whereas others have failed to demonstrate a significant difference. 1 Although the essential diagnostic criteria for RLS 2 have not yet been validated in PD patients, approximately 10% to 26% of PD patients suffer from RLS-like symptoms, 3-5 often years after manifestation of PD motor symptoms. 4 Other PD patients may develop RLS after successful DBS, when dopaminergic treatment is reduced. 6 A link between RLS and PD has been suggested. Both conditions respond well to dopaminergic treatment and are aggravated by dopaminergic antagonists. 7 They are both associated with periodic limb movements in sleep, which are improved with dopaminergic treatment, especially dopamine agonists. 8,9 However, whereas PD patients with (PD+RLS) and without RLS (PD-nonRLS) show increased echogenicity of the SNc on midbrain sonography (supporting the hypothesis of increased iron concentration), patients with idiopathic RLS are often identified with hypoechogenicity (supporting the hypothesis of decreased iron concentration). This suggests a different underlying pathogenesis, 10,11 probably related to iron storage and transport as well as to brain iron concentrations. Iron and ferritin levels in the cerebrospinal fluid have been found to be reduced in patients with iR...

Probable RBD Associates with the Development of RLS in Parkinson’s Disease: A Cross-Sectional Study

“…That is to say, RBD coexisting without other parasomnias or isolated sleep symptoms was rare. As the decreasing prevalence of tooth grinding with age, SB is not associated with PD but perhaps more likely with RLS [37, 38]. These above perhaps prompt a potential link between RBD and RLS, especially among PD patients.…”

Therapeutic advances in restless legs syndrome (RLS)

“…The main merit of these new criteria is that they specify that frequent confounders of RLS, denominated mimics, must be specifically excluded before making a positive RLS diagnosis. Mimics may account for up to 16% of individuals diagnosed with RLS in a primary RLS population and possibly even more in comorbid conditions in which symptoms similar to RLS occur as part of the primary disease (eg, polyneuropathy or Parkinson's disease). Some discussion has been generated by the fact that minor variations were introduced in the wording and structure of the criteria by medical societies.…”

Morbus Parkinson und Restless-legs-Syndrom – ein unterschätztes Problem?

“…Es gibt aber auch Personen, die unmittelbar auf die erste FCM-Infusion an sprechen. Bei Wiederholung einer erfolgreichen FeInfusion im Verlauf sind engmaschigere Laborkontrollen des Ferritins und der Transferrinsättigung notwendig, da der Ferritinwert nicht > 300 μg/l und die Transferrinsättigung nicht über > 45 % ansteigen sollten [13].…”

“…Zwischen 20-50 μg/l existiert eine gewisse Grauzone. Ferritinwerte < 50 μg/l mit einer Transferrinsättigung < 20 % im Serum werden als latenter Eisenmangel definiert[13].…”