Evaluation of Hypocalcemia Following Total Laryngectomy With and Without Thyroidectomy

OBJECTIVE

Hypoparathyroidism and associated hypocalcemia are well-established complications following laryngectomy. This study further characterizes the rates of hypocalcemia in patients undergoing total laryngectomy (TL) with and without thyroidectomy and hemithyroidectomy.

STUDY DESIGN

Retrospective cohort study.

SETTING

TriNetX.

METHODS

We queried TriNetX, a deidentified patient database, to identify patients who underwent TL with and without thyroidectomy and hemithyroidectomy. Rates of hypocalcemia, low parathyroid hormone (PTH), calcium, and calcitriol supplementation were compared between groups with multivariable repeated measures logistic regression.

RESULTS

We identified 870 patients in the TL without thyroidectomy cohort, 158 patients in the hemithyroidectomy cohort, and 123 in the total thyroidectomy cohort. Rates of hypocalcemia differed between patients receiving total thyroidectomy versus TL alone for 0 to 1 month (odds ratio [OR]: 2.88 [1.95-4.26]) 1 to 6 months (OR: 5.08 [2.29-11.3]), and 6 to 12 months (OR: 2.63 [1.003-6.88]) postoperatively, with adjustment for age at laryngectomy, race, ethnicity, and gender. Results were similar among those who received calcium supplementation. The rate of low PTH levels differed in these groups for 0 to 1 month (OR: 5.13 [3.10-8.51]), 1 to 6 months (OR: 3.47 [1.46-8.22]), and 6 to 12 months (OR: 3.63 [1.40-9.38]) following surgery. Rates of postoperative calcium supplementation were increased for patients receiving total thyroidectomy versus TL for 1 to 6 months (OR: 2.44 [1.62-3.68]), and 6 to 12 months following surgery (OR: 1.79 [1.18-2.72]).

CONCLUSION

Patients undergoing TL with total thyroidectomy have a higher risk of postoperative hypocalcemia compared to patients receiving TL alone. Risk of parathyroid injury in these patients may warrant further emphasis on PTH measurement after surgery and a multidisciplinary approach to management.

Hypocalcemia After Thyroidectomy in Patients with Prior Bariatric Surgery: A Propensity Score Matched Analysis from a National Administrative Database

Background: Studies have suggested that patients with prior gastric bypass may be at increased risk for hypocalcemia following thyroidectomy. Unfortunately, most of these studies are limited to case reports and small series. This study represents the largest sample size to date to assess the incidence of post-thyroidectomy hypocalcemia in patients with a history of bariatric surgery. Methods: The TriNetX Research Network was queried to retrospectively identify patients with prior bariatric surgery who underwent total thyroidectomy between 2011 and 2021. The incidence of hypocalcemia following surgery was compared with patients who underwent total thyroidectomy, and hemithyroidectomy with no history of bariatric surgery. Results: We identified 446 patients with a history of bariatric surgery and subsequent thyroidectomy, 29,346 patients with total thyroidectomy, and 19,603 patients with hemithyroidectomy alone. The one-month incidence of hypocalcemia was 54.7% in those with a history of bariatric surgery who underwent thyroidectomy, 43.9% in those with thyroidectomy alone (relative risk, RR = 1.2 [confidence interval, CI 1.1-1.4], p < 0.001), and 8.1% in those with hemithyroidectomy only (RR = 6.8 [CI 6.1-7.4], p < 0.001). Permanent hypocalcemia was documented in 11.4% of patients with prior bariatric surgery who underwent thyroidectomy, 7.7% of those with thyroidectomy only (RR = 1.5 [CI 1.1-1.9], p = 0.003), and 2.9% of patients with hemithyroidectomy alone (RR = 3.9 [CI 3.0-5.2], p < 0.001). Significant differences persisted after matching demographics, prior need for supplementation, and risk factors for hypocalcemia after thyroidectomy. When stratified by bariatric procedure, patients with a history of Roux-en-Y gastric bypass (RYGB) (n = 35) had a greater, although not statistically significant, risk of short-term hypocalcemia (51.4%; RR = 1.2 [CI 0.8-1.6], p = 0.37), and a significantly increased risk of permanent hypocalcemia (20.0%; RR = 2.6 [CI 1.3-5.1], p = 0.005) compared with thyroidectomy alone. Sleeve gastrectomy (SG) (n = 40) was not associated with an increased risk of short-term (40.0%; RR = 0.9 [CI 0.6-1.3], p = 0.62) or permanent (7.5%; RR = 1.0 [CI 0.3-2.9], p = 0.96) hypocalcemia. Conclusions: Prior RYGB, but not SG, may increase the risk of permanent hypocalcemia after thyroidectomy. Additional research is necessary to determine optimal prevention and treatment strategies to reduce morbidity in this population.

A coaxial excitation, dual-red-green-blue/near-infrared paired imaging system toward computer-aided detection of parathyroid glands in situ and ex vivo

Early and precise detection of parathyroid glands (PGs) is a challenging problem in thyroidectomy due to their small size and similar appearance to surrounding tissues. Near-infrared autofluorescence (NIRAF) has stimulated interest as a method to localize PGs. However, high incidence of false positives for PGs has been reported with this technique. We introduce a prototype equipped with a coaxial excitation light (785 nm) and a dual-sensor to address the issue of false positives with the NIRAF technique. We test the clinical feasibility of our prototype in situ and ex vivo using sterile drapes on 10 human subjects. Video data (1287 images) of detected PGs were collected to train, validate and compare the performance for PG detection. We achieved a mean average precision of 94.7% and a 19.5-millisecond processing time/detection. This feasibility study supports the effectiveness of the optical design and may open new doors for a deep learning-based PG detection method.

Development of an imaging device for label-free parathyroid gland identification and vascularity assessment

During thyroid surgeries, it is important for surgeons to accurately identify healthy parathyroid glands and assess their vascularity to preserve their function postoperatively, thus preventing hypoparathyroidism and hypocalcemia. Near infrared autofluorescence detection enables parathyroid identification, while laser speckle contrast imaging allows assessment of parathyroid vascularity. Here, we present an imaging system combining the two techniques to perform both functions, simultaneously and label-free. An algorithm to automate the segmentation of a parathyroid gland in the fluorescence image to determine its average speckle contrast is also presented, reducing a barrier to clinical translation. Results from imaging ex vivo tissue samples show that the algorithm is equivalent to manual segmentation. Intraoperative images from representative procedures are presented showing successful implementation of the device to identify and assess vascularity of healthy and diseased parathyroid glands.

Clinical Utility of Intraoperative Parathyroid Hormone Measurement in Children and Adolescents Undergoing Total Thyroidectomy

Background: Hypoparathyroidism is one of the most common complications for patients undergoing total thyroidectomy. Our study's primary objective was to assess if intraoperative PTH levels correlate with parathyroid gland function recovery time in pediatric patients following total thyroidectomy. Methods: Retrospective review of pediatric patients who underwent thyroid surgery at CHOP for demographics and laboratory test values (calcium, phosphorus, and parathyroid hormone). We defined Time of Recovery (TOR) as the time difference from first intra-operative parathyroid hormone level (ioPTH) timepoint until normalization of PTH (> 10 pg/mL) post-thyroidectomy. Calcium and vitamin D supplements were weaned following normalization of calcium and phosphorous levels postoperatively. Patients were excluded if they lacked three intraoperative PTH timepoints or were missing postoperative follow-up PTH data. Results: 65 patients (54 female), median age 15 (range 5-23 years), underwent thyroid surgery and met study inclusion criteria. The correlations of 2nd and 3rd ioPTHs with TOR were statistically significant (p < 0.05): the lower the ioPTH, the greater the recovery time. Stratifying patients into high-risk (2nd ioPTH ≤ 10 pg/mL), moderate-risk (2nd ioPTH between 10 and 20 pg/mL), and low-risk (2nd ioPTH ≥ 20 pg/mL) tertiles, the TOR decreased by orders of magnitudes from an average of 43.13 ± 76.00 to 6.10 ± 17.44 to 1.85 ± 6.20 days. These differences were statistically significant (p < 0.05). Conclusions: Our study results confirm the usefulness of intraoperative PTH levels to predict pediatric patient recovery post-surgery and provides useful anticipatory guidance to optimize timing and frequency of postoperative laboratory surveillance.

Intraoperative Assessment of Parathyroid Viability using Laser Speckle Contrast Imaging

Post-surgical hypoparathyroidism and hypocalcemia are known to occur after nearly 50% of all thyroid surgeries as a result of accidental disruption of blood supply to healthy parathyroid glands, which are responsible for regulating calcium. However, there are currently no clinical methods for accurately identifying compromised glands and the surgeon relies on visual assessment alone to determine if any gland(s) should be excised and auto-transplanted. Here, we present Laser Speckle Contrast Imaging (LSCI) for real-time assessment of parathyroid viability. Taking an experienced surgeon's visual assessment as the gold standard, LSCI can be used to distinguish between well vascularized (n = 32) and compromised (n = 27) parathyroid glands during thyroid surgery with an accuracy of 91.5%. Ability to detect vascular compromise with LSCI was validated in parathyroidectomies. Results showed that this technique is able to detect parathyroid gland devascularization before it is visually apparent to the surgeon. Measurements can be performed in real-time and without the need to turn off operating room lights. LSCI shows promise as a real-time, contrast-free, objective method for helping reduce hypoparathyroidism after thyroid surgery.