At initial diagnosis, patients with microprolactinoma showed higher HCT (median 42.8 [2.7] vs. 40.2 [4.0] %, p = 0.0122) and Hb (14.7 [1.2] g/dl vs. 14.0 [2.0], p = 0.0337) than those with macroprolactinoma (Table 1). This evidence concerns the gene GSTM1 and Microprolactinoma.