Hypoparathyroidism after total thyroidectomy: prospective evaluation and relation with early hypocalcemia.

Aim: Definitive hypoparathyrodism (hypo-PTH) represents one of the most dangerous complication after total thyroidectomy. Partial or total lesion or accidental removal of parathyroid glands is an unpredictable adverse event, although real incidence is not well defined, such as management of this deficit. We started a prospective evaluation of patients treated with total thyroidectomy in our centre, to identify incidence of hypo-PTH, symptomatic or not, in relation to incidence of early postoperative hypocalcemia in our experience.
Methods: We prospectively evaluated 177 patients treated for benign and malign pathology, measuring calcium before surgery and calcium and PTH at least three months after surgery. Postoperative hypocalcemia was observed in 37.3% of cases. Eight patients (4.5% of cohort) presented low level of PTH, at mean follow-up of 9.1 months. Positive predictive value for postoperative hypocalcemia was 12.1%, while negative predictive was 95.4%; confirming high sensitivity (100%) and low specificity (65.4%) for detecting hypo-PTH.
Discussion: All patients with late hypo-PTH presented hypocalcemia on early analysis, while no case with normal postoperative calcemia accounted with hypo-PTH: this may indicate calcemia as valid prognostic factor of good gland production, when is in the range. Moreover, isolated analysis is too limited to determine real predictability.
Conclusion: Technical standardization represents the best method for prevention of hypo-PTH. Early hypocalcemia is a prognostic factor, even with a low specificity, of deficit of PTH-production. This observation must be related to other known prognostic factors. Postoperative normal calcemia should be a positive prognostic factor of an acceptable PTHfunction, supported by large cohorts.
Key Words: Hypocalcemia, Parathormone, Thyroidectomy.