Histopathological pattern of thyroid diseases and its correlation with post-thyroidectomy hypocalcemia: a prospective study in iodine-sufficient Southern India

Abstract

Background: Increasing incidence of thyroid diseases requiring surgery and postoperative hypocalcemia after total thyroidectomy (TT) remains a concern. This prospective study evaluated the correlation between the histopathologic pattern of thyroid disease and the development of temporary and permanent hypocalcemia (>6 month) post-TT.Methods: Demographics and clinical profile of consecutive patients undergoing TT were documented. The final diagnosis was confirmed with histopathological examination (HPE) of thyroidectomy specimen. Serum corrected-calcium and intact parathormone was measured at baseline, 48-hour and 6-month post-TT.Results: Out of 328 subjects (mean age=35.5 year; M:F=65:263), 33.4% (n=109) and 7.6% (n=26) developed temporary and permanent hypocalcemia [calcium=8 mg/dl] post-TT. HPE comprised colloid goitre 33.2% (n=109), follicular adenoma 1.8% (n=6), Hashimoto’s/lymphocytic thyroiditis 16.8% (n=55), Graves’ disease 14% (n=46), adenomatous hyperplasia 19.8% (n=65), papillary thyroid carcinoma (PTC) 13.4% (n=44), follicular carcinoma 0.3% (n=1), medullary carcinoma 0.3% (n=1) and anaplastic carcinoma 0.3% (n=1). Multinomial regression analysis revealed that temporary hypocalcemia was associated with graves’ disease (Odds ratio: 11.6), PTC (10.3), follicular adenoma (16.7) and thyroiditis (17.5), while permanent hypocalcemia was associated only with thyroiditis (3.2), each p<0.01.Conclusions: Graves’ disease, thyroiditis and malignancy increased the risk of temporary post-thyroidectomy hypocalcemia by many-fold. Subjects with thyroiditis had 3.2-fold increased likelihood for developing permanent hypocalcemia. Hence thyroiditis, a benign pathology warrants high threshold for surgery with meticulous intraoperative dissection and in-situ preservation of parathyroid glands.