Predicting Clinical Post-Thyroidectomy Hypocalcemia Using PTH Levels: Comparing Our Experience To ATA Recommendations

  • Background/Purpose
    The American Thyroid Association has recently recommended a single postoperative PTH of 15 pg/mL or more to obviate calcium monitoring and/or supplementation after bilateral thyroid surgery. At our institution, a protocol that compares postoperative to preoperative PTH values, and set this threshold in an 80% decrease, is employed since 2013. Our purpose was to compare the performance of both protocols.

    Methods
    Retrospective review of patients that underwent simultaneous or staged bilateral thyroid surgery during the 2013-2015 period. Follow-up data was available for at least 3 weeks after surgery.

    Results
    A total of 240 patients met the inclusion criteria. According to our protocol, 77% of the patients met the criterion to obviate monitoring and/or supplementation; 4 of them suffered mild symptoms of hypocalcemia, but no severe complications occurred after discharge. Using the ATA recommendations, 66% of the patients would have met the criterion, and 2 of them suffered mild symptoms.

    No significant difference was found between the false negative rates of both protocols (7.8% vs 3.9%), but the proportion of candidates to early discharge was significantly higher in ours (77% vs 66%).

    Discussion & Conclusion
    The higher the threshold to predict postoperative hypoparathyroidism, the lower the probability of suffering symptoms after discharge. However, the number of candidates to early discharge is also reduced. By comparing preop-postop status, other factors that influence PTH may be cancelled. Although two PTH measurements are more expensive that only one, it may reduce the total costs by allowing an earlier discharge of a higher number of patients.

 

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