1. Section of Endocrinology and Nutrition, Hospital Universitario Insular, Las Palmas de Gran Canaria, Spain;
2. Department of Medical and Surgical Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain;
3. Mathematics Department, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain;
4. Service of Biochemistry, Hospital Universitario Insular, Las Palmas de Gran Canaria, Spain.