Endocrine Abstracts

We investigated 49 patients with non-functioning pituitary macroadenomas: 11 males, 38 females, age 31–78 y.o. (median 61). Extrasellar tumor expansion was observed in 46 (93.9%) patients: suprasellar – 41 (83.7%), laterosellar 27 (55.1%), and infrasellar 18 (36.7%) patients; combined types of extrasellar expansion – 36 (73.5%) patients.

Prolactin levels (PRL) varied from 115 to 1495 mU/l, hyperprolactinemia was found in 27 (55.1%) patients, macroprolactinemia and symptomatic hyperprolactinemia were excluded. PRL were correlated with vertical (r=0.65; P<0.001), frontal (r=0.53; P<0.001), and sagital (r=0.5; P<0.001) size of pituitary tumor and with total tumor volume (r=0.6; P<0.001).

Chiasmic syndrome (ChS) was observed in 33 (67.3%) of patients with MR-signs of chiasm compression by pituitary tumor. Prolactin levels, tumor size and total tumor volume were significantly higher in patients with ChS compared with without ChS (median (min; max)): prolactin 832 (160; 1495) vs 234 (115; 1056) mU/l; vertical size 25 (15; 50) vs 12 (8; 17) mm; frontal size 23 (12; 62) vs 14 (5; 33) mm; tumor volume 7680 (1190; 63 800) vs 1441 (280; 4350) mm³ respectively (P<0.001 for all). All patients with tumor volume >4360 mm³ and/or vertical tumor size >18 mm, frontal size >19 mm had chiasmic syndrome. A strong correlation was found between severity of chiasmic syndrome and tumor volume (r=0.8, P<0.001), prolactin levels (r=0.5; P<0.001). Among 33 patients with ChS, 30 (91%) persons had elevated prolactin levels.

Thus, in cases of nonfunctioning pituitary tumors prolactin levels were <1500 mU/l in our study. As prolactin levels correlated not only with vertical but also with frontal and sagital sizes of tumor, we suggest that not only pituitary stalk prelum but also intrapituitary compression of normal hypophysis might play role for dopamine control dysregulation. Vertical tumor size >18 mm, frontal size >19 mm, and hyperprolactinemia are strongly associated with chiasmic syndrome.