Glycoprotein hormone alpha-subunit in pituitary adenomas

Elevated serum glycoprotein hormone α-subunit (α-subunit) levels are seen in about one of six patients bearing pituitary adenomas. This finding has particular clinical significance in patients with nonfunctioning pituitary adenomas. Moreover, the measurement of α-subunit along with the calculation of the molar ratio between α-subunit and TSH, LH, or FSH is helpful in the diagnosis of glycoprotein hormone-secreting pituitary adenomas. Since serum α-subunit levels may vary greatly in several physiologic and pathologic conditions, care has to be taken to differentiate abnormal from normal states of α-subunit hypersecretion as well as to exclude causes of α-subunit overproduction only casually associated with the presence of pituitary tumors.