Correlation between Pituitary Insufficiency and Magnetic Resonance Imaging Finding in Non-Functioning Pituitary Adenomas

Background: Non-functioning pituitary adenomas (NFPAs) are characterized by the absence of clinical and biochemical evidence of pituitary hormone hypersecretion, and these tumors constitute approximately one third of all the tumors of the anterior pituitary. Recently, hormonal deficiencies have gradually evolved to become the leading presenting signs and symptoms in patients with NFPAs. We investigated pituitary hormonal insufficiencies according to the magnetic resonance imaging (MRI) findings in patients with NFPA. Methods: We evaluated the patients who were newly diagnosed with NFPA from 1997 through 2009. Among them, we analyzed 387 patients who were tested for their combined pituitary function and who underwent MRI. The severity of the hypopituitarism was determined by the number of deficient axes of the pituitary hormones. On the MRI study, the maximal diameter of the tumor, Hardy's classification, the thickness of the pituitary gland and the presence of stalk compression were evaluated. Results: The mean age was 46.85 +/- 12.93 years (range: 15-86) and 186 patients (48.1%) were male. As assessed on MRI, the tumor diameter was 27.87 +/- 9.93 mm, the thickness of the normal pituitary gland was 1.42 +/- 2.07 mm and stalk compression was observed in 201 patients (51.9%). Hypopituitarism was observed in 333 patients (86.0%). Deficiency for each pituitary hormone was most severe in the patients with Hardy type IIIA. Hypopituitarism was severe in the older age patients (P = 0.001) and the patients with a bigger tumor size (P < 0.001) and the presence of stalk compression (P < 0.001). However, the patients who had a thicker pituitary gland showed less severe hypopituitarism (P < 0.001). Multivariate analysis showed that age, tumor diameter and the thickness of pituitary gland were important determinants for pituitary deficiency (P = 0.004, P < 0.001, P = 0.022, respectively). Conclusion: The results suggest that the hormonal deficiencies in patient with NFPA were correlated with the MRI findings, and especially the tumor diameter and preservation of the pituitary gland.