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Tumor Biology

SUN-285 - Comparative Characteristics of Multiglandular Disease in Sporadic vs. MEN-1-Associated Primary Hyperparathyroidism

Sunday, June 14, 2026
9:00 AM - 4:00 PM CT
Location: ENDOExpo; Poster Floor


Background:
Multiglandular disease (MGD) is a significant challenge in primary hyperparathyroidism (PHPT), occurring in 10-15% of cases. While often linked to hereditary syndromes,
especially multiple endocrine neoplasia syndrome type 1 (MEN-1), MGD is also prevalent in sporadic PHPT (8-33%). This variability complicates preoperative localization and surgical management.

Objective:
To compare clinical, biochemical, and pathological profiles of MGD in sporadic vs. MEN-1-associated PHPT.

Methods:
We conducted a single-centre retrospective study at the Endocrinology Research Centre between 2016 and 2025, analyzing 202 patients: 118 with MEN-1-associated PHPT (MEN+) and 84 with sporadic PHPT (MEN-). Inclusion in the MEN+ group required a confirmed pathogenic germline variant in the MEN1 gene, whereas mutation was excluded in the sporadic (MEN-) cohort.

Results:
The groups were comparable in baseline Ca-P and bone metabolism markers (PTH, total and ionized Ca, P, 24-hour urinary Ca, ALP, CTx, osteocalcin; p>0.05). Serum 25(OH)D was lower in MEN+ patients: 18.8 [13.3; 25.9] vs. 32.88 [20.60; 39.80] ng/mL (p < 0.0001). Nephrolithiasis was more prevalent in the MEN+ group (67.7% vs. 48.8%, p=0.03), while vertebral fracture rates were similar. MEN- patients had significantly lower radius BMD, though BMD at other sites was comparable. Peptic ulcer disease was more frequent in MEN+ (42.3% vs. 10.4%, p< 0.0001).
Histological analysis revealed a predominantly multiglandular pattern (involvement of ≥3 glands: 55.8%) in MEN+ patients, compared to two-gland disease (66.7%) in the MEN- group. The frequency of ectopic glands did not differ significantly (7.8% vs. 17.8%, p=0.09). Preoperative imaging (ultrasound, CT, scintigraphy) showed consistently lower concordance with surgical/histological findings in the MEN+ group. Histological type distribution was similar (p>0.05): adenomas were most common (55.3% MEN+ vs. 68.7% MEN-), followed by hyperplasias (21.2% vs. 14.4%). Atypical tumors and mixed patterns were rarer; a single carcinoma was found in the MEN- group.
Disease remission after initial surgery was 58.1% (MEN+) vs. 71.6% (MEN-). Recurrence rates were 26.9% vs. 10.8%, and persistence rates were 15.0% vs. 17.6%. However, the overall distribution of these surgical outcomes did not differ significantly between groups (p=0.247).

Conclusion:
Our data suggest that MEN-1-associated MGD presents a distinct profile with differing clinical, metabolic, and pathological features. The suboptimal performance of standard preoperative imaging and the trend toward inferior surgical outcomes in this group highlight the limitations of current diagnostic protocols and argue for a modified surgical strategy, where bilateral neck exploration may be the preferred initial approach.

Funding:
Russian Science Foundation, agreement №24-15-00269.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*