Serum-negative chronic thyroiditis: an insidious nosographic entity cause of hypothyroidism, goiter and difficult thyroidectomy.

PURPOSE: Although there are no histological diagnoses of certainty, the existence of antibody-negative chronic follicular thyroiditis has recently been hypothesized. Therefore, we conducted a study correlating the histopathological data with the clinical and surgical outcomes.

METHODS

A retrospective analysis was conducted including all patients who underwent thyroidectomy between November 2014 and October 2020 at the Surgery Division of the AOU "Luigi Vanvitelli" in Naples. Patients were classified into three groups, correlating the histological data to the anti-thyroperoxidase and anti-thyroglobulin antibodies levels. We distinguished patients without thyroiditis (TF), with antibody-positive thyroiditis (SPT), and with seronegative thyroiditis (SNT). Surgical complications and pre-operative hypothyroidism were evaluated and compared statistically.

RESULTS

We enrolled 476 patients divided into three groups: TF (322 patients), SPT (116 patients), and SNT (38 patients). Regarding complications, we observed 6.5% of transient hypoparathyroidism in the TF group, 14.7% in the SPT group and 13.2% in the SNT group (p < 0.05). There were no statistical differences among groups regarding permanent hypoparathyroidism, recurrent laryngeal nerve paralysis and postoperative bleeding. We observed 6.2% of hypothyroidism in the TF group, 33.6% in the SPT group, and 23.7% in the SNT group (p 0.01). In the SPT and SNT groups, the frequency of hypothyroidism was comparable (p: 0.31).

CONCLUSIONS

These results show that chronic serum-negative thyroiditis represents a nosographic entity, comparable to antibody-positive chronic thyroiditis and statistically correlated to an increase of post-operative hypoparathyroidism and pre-operative hypothyroidism. Serum-negative follicular thyroiditis is a cause of hypothyroidism, goiter in the absence of iodine deficiency, and difficult thyroidectomy.