Four-dimensional computed tomography (4D-CT) for preoperative parathyroid localization: A good study but are we using it?

Hypercalcemia with a parathyroid hormone level of ≤50 pg/mL: Is this primary hyperparathyroidism?

BACKGROUND

Primary hyperparathyroidism is characterized by hypercalcemia with inappropriately normal or elevated parathyroid hormone. However, the absolute parathyroid hormone value that is defined as inappropriately normal is unclear. We reviewed our experience with parathyroidectomy in patients with hypercalcemia and parathyroid hormone of ≤50.0 pg/mL (normal range 12.0-88.0 pg/mL).

METHODS

A total of 2,349 patients underwent parathyroidectomy for primary hyperparathyroidism between 2000 and 2021. Of these, 149 patients had preoperative parathyroid hormone ≤50.0 pg/mL (parathyroid hormone ≤50). The biology and outcomes were compared to patients with parathyroid hormone >50.0 pg/mL (parathyroid hormone >50).

RESULTS

Of the parathyroid hormone ≤50 patients, the median parathyroid hormone was 40.0 pg/mL (range 11.6-50.0 pg/mL). All patients were found to have abnormal hypercellular parathyroid glands with a cure rate of 96.7%. When compared to the parathyroid hormone >50 group, the parathyroid hormone ≤50 group was younger (56 ± 15 vs 60 ± 14 years, P < .001) with a lower body mass index (28.7 ± 7.0 kg/m² vs 31.2 ± 7.9 kg/m², P < .001), higher rate of fatigue (73.2% vs 63.0%, P = .033), and higher rate of multiglandular disease (58.9% vs 31.9%, P < .001). There was no difference between the groups with respect to patient demographics, rate of previous parathyroidectomy, surgical cure, or postoperative complications (persistent or recurrent hyperparathyroidism and hypocalcemia).

CONCLUSION

Patients with hypercalcemia and parathyroid hormone ≤50 pg/mL have a similar clinical presentation and rate of surgical cure to other primary hyperparathyroidism patients and should be considered for parathyroidectomy. Most of these patients have multiglandular disease and thus should be considered for bilateral parathyroid exploration.

Advances in Endocrine Surgery

Recent changes in the landscape of endocrine surgery include a shift from total thyroidectomy for almost all patients with papillary thyroid cancer to the incorporation of thyroid lobectomy for well-selected patients with low-risk disease; minimally invasive parathyroidectomy with, and potentially without, intraoperative parathyroid hormone monitoring for patients with well-localized primary hyperparathyroidism; improvement in the management of parathyroid cancer with the incorporation of immune checkpoint blockade and/or targeted therapies; and the incorporation of minimally invasive techniques in the management of patients with benign tumors and selected secondary malignancies of the adrenal gland.

Association Between Size of Dominant Candidate Lesion on Four-Dimensional CT and Four-Gland Hyperplasia among Patients with Primary Hyperparathyroidism

BACKGROUND

Four-dimensional (4D) CT localization allows minimally invasive parathyroidectomy as treatment for primary hyperparathyroidism (PHPT), but false positive localization is frequent. We sought to characterize the ability of 4D CT to predict four-gland hyperplasia (HP) based on the size of candidate lesions.

STUDY DESIGN

We retrospectively analyzed patients with PHPT who underwent 4D CT imaging and parathyroidectomy between 2014 and 2020 from a prospectively collected institutional database. The cohort was stratified into two groups, HP vs single adenoma (SA) and double adenoma (DA), based on operative findings and pathology. Logistic regression models assessed the association between the greatest diameter of the dominant candidate lesion on 4D CT and the outcomes of four-gland hyperplasia vs SA and DA.

RESULTS

Among a cohort of 240 patients, 41 were found to have HP, and 199 had adenomas (SA = 155, DA = 44). Patients with HP were less likely to have a preoperative calcium level greater than 1 mg/dL above the upper limit of normal compared with patients with adenomas (63% vs 81%, p = 0.02) and more likely to report symptoms (61% vs 43%, p = 0.04). After adjusting for BMI, we found an estimated 13% reduction in odds of HP for every 1-mm increase in the greatest diameter of dominant candidate lesions identified on 4D CT scan (odds ratio 0.87, 95% CI 0.78 to 0.96, p = 0.009).

CONCLUSIONS

A smaller size of the dominant lesion on 4D CT scan is associated with an increased risk of HP in PHPT. Use of 4D CT imaging localization may provide evidence for differentiating HP from adenomas.