Comparison of Anterior Pituitary Function between Patients with GH-secreting Macroadenoma and those with Nonfunctioning Macroadenoma / 대한내분비학회지

ABSTRACT

BACKGROUND: Some of the deficiencies in anterior pituitary function identified in subjects with macroadenomas appear to represent irrevemible necrosis of normal pituitary cells, and in addition reversible damage to viable glandular tissue and/or incomplete interruption of local circulation by compression of pituitary stalk may also contribute significantly to hypopituitarism. So anterior pituitary function may actually improve in some patients undergoing successful tumor resection or reduction in tumor size. Although direct comparisons of pituitary function among the various pituitary tumors are not presently available it was reported that there is some difference in the degree of pituitary impairment between patients with nonfunctioning macroadenoma(NFMA) and those with GH-secreting macroadenoma(GHMA).In this study, to investigate the difference in the degree of hypopituitarism we compared anterior pituitary function in subjects with NFMA to that in patients with GHMA. METHODS: In this retrospective study, preoperative and postoperative anterior pituitary function was assessed by clinical findings, basal hormone levels and/or combined pituitary stimulation test in 29 subjects with NFMA and in 24 subjects with GHMA. RESULTS: 1. There was no difference in age, sex, tumor size distribution between the two groups. 2. Preoperatively, NFMA patients had a higher prevalence of secondary hypothyroidism(34% vs. 5%; p(0.02) compared to subjects with GHMA. Patients with NFMA also had a higher prevalence of more severe pituitary failure compared with acromegalic patients; 48% of the patients in this group had more than one pituitary hormone axis impaired compared to 17% in the acromegalic group(p0.03). 3. Postoperatively, NFMA patients also had a higher prevalence of secondary hypoadrenalism (52% vs. 11%; p 0.01) compared with acromegalic patients. Additionally, the prevalence who had more than one pituitary hormone axis impaired was still greater in NFMA patients than in the acromegalic group(57% vs. 22%; p=0.054). 4. No correlation was found between the severity of pituitary failure and tumor size or extension in both groups before and after surgery. CONCLUSION: These findings suggest that anterior pituitary function is relatively better preserved in patients with GHMA than those with NFMA and that this difference is independent of tumor size and extension. The mechanism underlying the lower rate of hypopituitarism in acromegalics with macroadenoma remains to be elucidated.