Serum chromogranin A concentration in hyperthyroidism before and after medical treatment.

Objective: The aim was to evaluate changes in chromogranin A (CgA) concentration in hyperthyroidism and to assess its metabolic correlations.

Methods: We studied CgA levels in hyperthyroidism. First, 38 hyperthyroid patients matched with 86 normal controls were studied after an overnight fast. Second, 30 if the 38 patients were followed up for 6 months with medical antithyroid drug therapy (carbimazole). In the first study, after 10-12 h overnight fasting, blood was collected for measurement of CgA, glucose, insulin, intact proinsulin, and thyroid function. These variables were remeasured in the second study for the patients after attainment of euthyroidism with the antithyroid drug carbimazole for 6 months.

Results: Pretreatment CgA level was significantly higher in patients compared with controls. CgA levels dropped significantly to levels similar to those of controls after antithyroid therapy. Although baseline and follow-up fasting glucose, insulin, and intact proinsulin demonstrated similar pattern of CgA changes before and after medical treatment, CgA did not correlate with any of them. However, CgA levels demonstrated a significant positive correlation with free T(3) and free T(4) only.

Conclusion: These studies demonstrate that untreated hyperthyroidism is associated with elevated CgA level that changes in parallel to thyroid status. It is therefore possible to use CgA concentration as a potential marker of disease activity in hyperthyroidism.