1. Laboratory of Medicine, Department of Clinical Biochemistry , Hospital Universitario Central de Asturias , Oviedo , Asturias , Spain
2. Department of Clinical Biochemistry , Hospital Álvarez Buylla , Mieres , Asturias , Spain
3. Department of Clinical Biochemistry , Hospital Universitario San Agustín , Avilés , Asturias , Spain
4. Department of Pneumology , Hospital Universitario Central de Asturias , Oviedo , Asturias , Spain