The third category involves data with inconsistent evidence that might be the objective of future studies to a better understanding; for instance, a longer pre-surgery dialysis duration [104,127], obesity [84,110], a higher total tumor weight [108], an elevated pre-surgery calcitonin [104], prior use of cinalcet [111], the co-presence of brown tumors and osteitis fibrosa cystica as seen in PHPT [137,148], GNAS mutation [119] (Figure 2). This evidence concerns the gene GNAS and obesity due to melanocortin 4 receptor deficiency.