ORIGINAL ARTICLE Acylated ghrelin: A potential marker for fibromyalgia? D. Homann 1 , F.M. Louzada 2 , S.M. Góes 1 , S. Roizenblatt 3 , A.L. Lopes 4 , Á.R. de Oliveira 4 , N. Leite 1 1 Department of Physical Education, Universidade Federal do Paraná, Curitiba, Brazil 2 Department of Physiology, Universidade Federal do Paraná, Curitiba, Brazil 3 Department of Psychobiology, Universidade Federal de São Paulo, São Paulo, Brazil 4 Superior School of Physical Education, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil Correspondence Diogo Homann E-mail: diogomann@hotmail.com Funding sources None declared. Conflicts of interest The authors declare that they have no conflicts of interest. Accepted for publication 28 January 2013 doi:10.1002/j.1532-2149.2013.00296.x Abstract Background: Fibromyalgia is characterized by chronic widespread pain and sleep disturbances. Overweight and obesity, which lead to metabolic changes, are additional comorbidities that are rarely explored, although they are highly prevalent in patients with fibromyalgia. Methods: We compared the plasma levels of leptin and acylated ghrelin in 17 women with fibromyalgia (patients) and 16 healthy women (controls) with similar age, anthropometric measurements and levels of physical activity. We also investigated the relationships between these two neuropeptides and sleep and various pain characteristics in patients with fibromyalgia. Anthropometric measurements were recorded, and physical activity levels were assessed using a questionnaire. Pain intensity was measured using visual analogue scales (weekly general and mean pain scores). Sleep was assessed using an accelerometry technique. Results: Compared to the control group, the patient group had increased leptin levels (patients: 22.4  10.6 vs. controls: 13.3  17.9 ng/mL; p < 0.01) and decreased acylated ghrelin levels (patients: 126.7  47.8 vs. controls: 183.3  102.2 pg/mL; p = 0.048). The leptin level was not significantly correlated with any of the variables. Acylated ghrelin level was inversely correlated with the weekly mean pain score (r =-0.67, p < 0.01) and the weekly general pain score (r =-0.67, p < 0.01). Multiple regression analysis revealed that the variations in acylated ghrelin levels accounted for 35% of the weekly general pain and 29% of the weekly mean pain variability. Conclusions: These findings indicate that the decreased acylated ghrelin levels in women with fibromyalgia are related to pain intensity. 1. Introduction Fibromyalgia is a chronic painful condition with a multifactorial aetiology. Its diagnosis is based on multiple symptoms, including musculoskeletal pain, fatigue, non-restorative sleep, cognitive impairments and somatic symptoms (Wolfe et al., 2010). Although it is rarely discussed in the literature, a prominent comor- bidity of fibromyalgia is a tendency to be overweight [body mass index (BMI)  25 kg/m 2 ] (Ursini et al., 2011). Indeed, high rates of overweight patients with fibromyalgia (70–76%) have been reported (Bennett et al., 2007; Okifuji et al., 2010; Kim et al., 2012a). Obesity (BMI  30 kg/m 2 ), which is present in approximately 45% of patients with fibromyalgia (Okifuji et al., 2010; Kim et al., 2012a), can aggravate the symptoms (Yunus et al., 2002; Okifuji et al., 2010). Biomarkers that are involved in regulating body weight gain and energy homeostasis, such as leptin, which inhibits food intake and increases energy expenditure (Zhang et al., 1994), and ghrelin (Kojima et al., 1999), which induces a positive energy balance and increase of adiposity (Van der Lely et al., 2004), may assist in understanding the relationship between the tendency 1 Eur J Pain •• (2013) ••–•• © 2013 European Federation of International Association for the Study of Pain Chapters