In a study of 97 women (50 with PCOS and 47 age- and BMI- matched healthy controls), although circulating total osteocalcin was 44% lower in the PCOS group, carboxylated osteocalcin was 75% higher (unlike other measures of bone biochemistry such as PTH, osteoprotegerin, and vitamin D levels which were similar), independent of obesity (86). Here, PTH is linked to obesity due to melanocortin 4 receptor deficiency.