Analytical Differences in Intraoperative Parathyroid Hormone Assays

An individual approach to intraoperative parathyroid hormone measurement during total thyroidectomy

PURPOSE

Hypocalcemia is a common complication of thyroidectomy. Measurement of the intraoperative serum parathyroid hormone (PTH) levels became an established technique but it requires further improvements. We aimed to assess intraoperative PTH level testing results against the hypothesis that the PTH assay may be performed almost immediately after thyroid gland removal.

METHODS

A retrospective cohort study. During total thyroidectomy surgery, the patients had PTH levels measured at the cutting time and again immediately after the thyroid gland is removed. Post-operatively, serial total blood calcium levels were obtained twice daily and recorded.

RESULTS

Among 63 enrolled patients, 39 had multinodular goiter, 15 thyroid carcinoma, and nine had Graves' disease. The mean age was 59.8 ± 15.3 years, 43 females. The mean PTH level before surgery was 45.8 ± 22.0 pg/mL. Post-operatively, 11/63 patients developed hypocalcemia with serum calcium levels <8 mg/dL. Four patients with ≥50 % decrease in PTH concentration were normocalcemic a day after surgery and were discharged early. Four patients with ≥70 % PTH decrease were treated accordingly during prolonged hospitalization and did not suffer from permanent hypocalcemia. The cut-off value of 70 % decrease after the gland removal was able to predict postoperative hypocalcemia with a sensitivity of 100 %, specificity 82.9 %, PPV 60.0 % and NPV 100 %.

CONCLUSION

Measurements of intraoperative PTH may not be performed at fixed time intervals but after 1-2 min after removal of the thyroid gland. Defining those not at risk would allow the majority of patients to be waived from post-operative blood calcium testing and safely discharged early after surgery.

Association of Implementation of Operating Room-Based Parathyroid Hormone Testing with Operative Time and Cost

BACKGROUND

Intraoperative parathyroid hormone (IOPTH) testing facilitates focused parathyroidectomy to establish biochemical cure but may be time-consuming. A dedicated immunoassay machine was relocated to the operating room for IOPTH. These data seek to determine association of operating room-based IOPTH with operative time, laboratory turnaround time (TAT), and cost.

METHODS

Patients who underwent parathyroidectomy from June 2017 to February 2020 were reviewed. Clinical and demographic data, operative time, and TAT were collected. Patients were compared by operation dates pre- or post-machine acquisition. A cost model was created to evaluate cost of care before and after operating room-based testing.

RESULTS

A total of 285 patients were included. Post-machine, median operative time decreased from 69 minutes (interquartile range [IQR] 60 to 84) to 57 minutes (IQR 50 to 84.5), p 0.03. Additionally, median TAT for IOPTH values (preoperative, 0, 5, 10, and 15 minutes) decreased post-machine: time preoperative, 29 minutes (IQR 23 to 40) vs 18 minutes (IQR 17 to 23.5), p < 0.001; time 0, 33 minutes (IQR 27 to 39) vs 18.5 minutes (17.5 to 21), p < 0.001; time 5 minutes, 31 minutes (IQR 26 to 36) vs 20 minutes (IQR 18.5 to 21), p < 0.001; time 10 minutes, 32 minutes (IQR 27 to 39) vs 20 minutes (IQR 18.5 to 22.5), p < 0.001; and time 15 minutes, 30 minutes (IQR 26 to 36) vs 19 minutes (IQR 17 to 21), p < 0.001. Total costs pre- and post-machine were $4,442 and $4,111, respectively. With $331 cost reduction per operation and 127 operations per year, the IOPTH machine pays for itself in 3 years, or 378 surgeries, and saves $168,589 in the machine's remaining 4-year life span.

CONCLUSIONS

Operating room-based parathyroid hormone testing results in improved operating productivity by decreasing result TAT and operative time and reduces cost.

Data on length of parathyroidectomy surgery and intraoperative parathyroid hormone (PTH) assay turnaround times following a switch in the location for intraoperative PTH testing from near point-of-care to central laboratory

Intraoperative monitoring of parathyroid hormone (PTH) is commonly used during parathyroidectomies. There are a number of practical challenges in achieving rapid turnaround time (TAT) for intraoperative PTH testing, whether the testing is performed point-of-care, near point-of-care, or in a central clinical laboratory. In the related research article, we analyzed a decade of data from 3025 intraoperative PTH tests on 897 unique patients. Of these, 1787 tests on 514 unique patients (375 female, 139 male) occurred while intraoperative PTH measurement was done as near point-of-care testing; the remaining 1238 tests on 383 unique patients (282 female, 101 male) occurred after a switch to intraoperative PTH measurement by the hospital central laboratory. The data in this article provides the patient age, gender, location of surgery (main operating rooms vs. ambulatory surgery center), incision to close time for surgery, and operation start to end times. For the central laboratory testing, additional data are provided for the intraoperative PTH TAT. The analyzed data is provided in the supplementary tables included in this article. Plots of operation start and end times are also included. The dataset reported is related to the research article entitled "Evaluation of Switch from Satellite Laboratory to Central Laboratory for Testing of Intraoperative Parathyroid Hormone" [D. Jacob, G. Lal, D.R. Voss, T. Bebber, S.R. David, J. Kulhavy, S.L. Sugg, A.E. Merrill, M.D. Krasowski, Evaluation of Switch from Satellite Laboratory to Central Laboratory for Testing of Intraoperative Parathyroid Hormone, Pract. Lab. Med. (2020) 22: e00176] [1].

Evaluation of switch from satellite laboratory to central laboratory for testing of intraoperative parathyroid hormone

Objectives

The aim of this study was to evaluate testing turnaround time (TAT) and incision to close time in parathyroid surgeries before and after switching intraoperative parathyroid hormone (PTH) testing from a near point of care location to a central clinical laboratory.

Design and Methods

This retrospective study covered a ten-year period. Both testing locations used the same Roche Diagnostics PTH immunoassay but on different analyzers. The predominant site for surgeries was the main operating rooms (ORs) in an adjacent building, with a limited number of parathyroid surgeries performed at a more distant ambulatory surgery center (ASC). Under ideal conditions, TAT for near point-of-care testing was 20 ​min, although multiple factors could increase TAT. Incision to close time from the electronic health record was used to define time of surgery.

Results

A total of 897 unique patients were identified for which 3031 orders for intraoperative PTH were placed (383 unique patients and 1244 orders after switch in testing site). The average total TAT times for testing (mean ​± ​SD) in the central laboratory were 23.9 ​± ​16.0 ​min (median, 22 ​min) for all specimens, 22.8 ​± ​7.9 ​min (median, 21 ​min) for main OR specimens, and 26.4 ​± ​7.1 ​min (median, 25 ​min) for ASC specimens. Incision to close time for parathyroidectomies showed decreases in mean, median, and standard deviation following testing change.

Conclusions

Surgery time for parathyroidectomies may remain consistent or decrease if intraoperative PTH testing is moved from a near point of care to a central laboratory.

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Turnaround around time for intraoperative parathyroid hormone (PTH) analysis in a central laboratory was evaluated.

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Surgery incision to close times were compared to 514 surgeries with intraoperative PTH performed as near point of care.

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Pre-analytical factors, especially transport time, were the major variable impacting turnaround time.

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The mean, median, and standard deviation for surgery incision to close times decreased in the switch to the central laboratory.