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Paper 8 (1045)
REVISITING LITHIUM-ASSOCIATED HYPERPARATHYROIDISM IN THE ERA OF INTRAOPERATIVE PARATHYROID HORMONE MONITORING (IOPTH)
Background: Chronic lithium therapy has been identified as a cause of primary hyperparathyroidism (HPT). The utility of IOPTH in these patients is unknown. We hypothesized that the incidence of multiglandular disease may be higher in these patients and consequently, that the ability of IOPTH monitoring to predict normocalcemia may be limited.
The 26th Annual Meeting of the American
Association of Endocrine Surgeons
April 3rd- 5th,2005 - Paradisus Riviera Cancun.
Jonathan Hundley MD; Gerard Doherty MD; Derek Woodrum, MD; Brian Saunders MD; and Paul Gauger, MD.
University of Michigan, Ann Arbor, Michigan
Methods: Twelve patients [10F, 2M; median age 54 (range 36-74)] developed HPT during or after chronic lithium therapy. All underwent parathyroidectomy (2000-2004) guided by IOPTH. Intraoperative criteria used to determine curative resection were a decrease of = 50% from highest baseline and a fall into the normal range (12-75 pg/mL). Cure of HPT was defined by normocalcemia at most-recent follow-up. Descriptive statistics are expressed as mean ± SEM.
Results: Preoperatively, mean calcium was 11.0 ± 0.1 mg/dL and mean PTH was 116 ± 12 pg/mL. Six of 12 patients (50%) had recognized multiglandular disease confirmed by IOPTH levels. Mean highest IOPTH baseline was 239 ± 60 pg/mL. Final IOPTH level (10 minutes after excision of single gland or final level after excision of multiple glands) was 47 ± 6 pg/mL, yielding a mean fall from baseline of 65 ± 7%. Although 10 of 12 patients met IOPTH criteria for curative resection, only 8 of 10 remain normocalcemic. The 2 patients who did not meet IOPTH criteria both remain normocalcemic. Mean postoperative calcium for all patients was 9.5 ± 0.2 mg/dL at a median postoperative follow up of 2.5 months (range 0.5-31 months). Of the 10 normocalcemic patients, 5 have hyperparathormonemia (mean PTH 111 ± 11 pg/mL) which may be concerning for early recurrence.
Conclusions: Utilizing IOPTH monitoring, the incidence of multiglandular disease in HPT following chronic lithium exposure is both higher than standard HPT, and higher than previously appreciated. The ability of IOPTH to predict durable normocalcemia is limited. These observations cause us to reevaluate whether a more aggressive initial parathyroid resection is indicated for these patients.