GDF15 and obesity due to melanocortin 4 receptor deficiency: Of the nine biomarkers analyzed, two were associated with sex (higher myoglobin levels in men and higher NT-proBNP levels in women), two with age (higher GDF-15 and big ET-1 levels in older adults), two with obesity (higher NT-proBNP and CKMB levels in participants who were obese), and one with chronic kidney disease (big ET-1).