What is the utility of parathyroid hormone level to predict postthyroidectomy hypocalcemia?
In this systematic review, accuracy, sensitivity, and specificity of parathyroid hormone level ranged widely. For an absolute parathyroid hormone level threshold, the median accuracy, sensitivity, and specificity were 86%, 85%, and 86%, and for a percentage change over time the median accuracy, sensitivity, and specificity were 89%, 88%, and 90%.
A single parathyroid hormone level threshold is not a reliable measure of hypocalcemia.
There has been an increased interest in measuring parathyroid hormone (PTH) levels as an early predictive marker for the development of hypocalcemia after total thyroidectomy. However, significant variation exists in the timing, type of assay, and thresholds of PTH in the literature.
We performed a systematic review to examine the utility of PTH levels in predicting temporary postthyroidectomy hypocalcemia.
A systematic literature review of studies published prior to May 25, 2016 was performed within PubMed, EMBASE, SCOPUS, and Cochrane databases using the following terms and keywords: “thyroidectomy,” “parathyroid hormone,” and “hypocalcaemia,” “calcium,” or “calcitriol.” Each candidate full-text publication was reviewed by 2 independent reviewers and selected for data extraction if the study examined the prognostic significance of PTH obtained within 24 hours after thyroidectomy to predict hypocalcaemia. Studies were excluded if calcium supplementation was used routinely or based on a PTH level. Study characteristics, PTH parameters used to predict hypocalcemia, and their respective accuracies were summarized.
The initial search yielded 2417 abstracts. Sixty-nine studies, comprising 9163 patients, were included. Overall, for an absolute PTH threshold, the median accuracy, sensitivity, and specificity were 86%, 85%, and 86%, respectively. For a percentage change over time the median accuracy, sensitivity, and specificity were 89%, 88%, and 90%, respectively.
Conclusions and Relevance
The existing literature regarding PTH levels to predict postthyroidectomy hypocalcemia is extremely heterogeneous. A single PTH threshold is not a reliable measure of hypocalcemia. Additional prospective studies controlled for timing of laboratory draws and a priori defined PTH thresholds need to be performed to ascertain the true prognostic significance of PTH in predicting postthyroidectomy hypocalcaemia.
Mathur A, Nagarajan N, Kahan S, Schneider EB, Zeiger MA. Association of Parathyroid Hormone Level With Postthyroidectomy Hypocalcemia: A Systematic Review. JAMA Surg. 2018;153(1):69–76. doi:10.1001/jamasurg.2017.3398
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