MSTN and medullary thyroid gland carcinoma: However, the use of myostatin for the diagnosis and prognosis of cachexia is affected by several issues: in particular, contradictory results regarding the correlation of its high serum levels and muscle wasting were reported in sarcopenic patients due to age and gender differences [67], while decreased serum levels of myostatin were found in patients with lung, colorectal, and medullary thyroid cancer [68,69].