Hypothyroidism following subacute thyroiditis

Abstract

The occurrence of permanent overt or subclinical hypothyroidism following subacute thyroiditis (SAT) was studied in 32 patients during 0.75\p=n-\13 years (mean 4.2 years) of follow-up. Permanent hypothyroidism developed in 2 patients in whom a characteristic feature was persistence of circulating thyroid antibodies in high titres from the onset of SAT indicating the presence of autoimmune thyroiditis. One also showed cytological evidence of autoimmune thyroiditis. In another patient subclinical hypothyroidism demonstrated by an exaggerated TSH-response to TRH, persisted after hemithyroidectomy during the acute phase. In addition, transient overt hypothyroidism developed immediately after the acute phase in 3, and subclinical hypothyroidism in 2 patients. Apart from the 2 patients with evidence of autoimmune thyroiditis, circulating thyroid antibodies were found in 15 others. The titres were usually low and disappeared in most cases after a transient rise. It is concluded that permanent hypothyroidism is likely to develop after SAT only in the presence of autoimmune thyroiditis or after thyroid surgery.

Reactivity of anti-thyroid antibodies to thyroglobulin tryptic fragments: comparison of autoimmune and non-autoimmune thyroid diseases

“…The more frequent reaction to the peptide of 80 kDa in patients with subacute thyroiditis does not indicate a pathogenic role but rather seems to represent an epiphenomenon, since follicular destruction and cell death probably release not only thyroglobulin, but also endoproteases and peptides produced by their action. Many authors have reported the development of Hashimotos thyroiditis after subacute thyroiditis (25)(26)(27)(28). It would be interesting to determine the repertoire of antithyroglobulin antibodies in these patients in order to elucidate some of the immune mechanisms involved or to identify a subtype of antithyroglobulin antibody.…”

Graves disease presenting as painful thyroiditis

“…The initial presentation with fever and extreme thyroid tenderness indicated subacute thyroiditis, but the normal erythrocyte sedimentation rate and the radioisotope studies refuted that diagnosis. Subacute thyroiditis frequently has a phase of hyperthyroidism [5,6], but is associated with a low uptake of radioiodide and a non-diffuse pattern of distribution of the consumed isotope [5]. Autoimmune thyroiditis, clinically seen as either Hashimoto disease with or without hypothyroidism or Graves disease with hyperthyroidism, may rarely follow an episode of subacute thyroiditis [4,5,7].…”

“…Subacute thyroiditis frequently has a phase of hyperthyroidism [5,6], but is associated with a low uptake of radioiodide and a non-diffuse pattern of distribution of the consumed isotope [5]. Autoimmune thyroiditis, clinically seen as either Hashimoto disease with or without hypothyroidism or Graves disease with hyperthyroidism, may rarely follow an episode of subacute thyroiditis [4,5,7]. However, with subsequent Graves disease, there is a defined time interval between the development of a painful thyroid and the hyperthyroidism [7].…”

“…T4, T3, and T3U were by ARIA II system (BectonDickinson Immunodiagnostics, Salt Lake City, Utah, USA), and TSH by immunoradiometric assay (Serono Diagnostics, Norwell, Massachusetts, USA) with a lower level of sensitivity of 0.1 gU/ml. For TSAb assay human thyroid cells were cultured in hypotonic medium [5]. % refers to the increase in cyclic AMP in the medium due to the addition of the patient's IgG (1.5 mg/ml) versus that in control cultures.…”

“…Depending upon the point at which investigation is initiated, there are frequently clinical and laboratory features of hyperthyroidism but with a negligible rate of uptake of radioactive iodide [6]. Long-term sequelae are unusual although subsequent permanent hypothyroidism [4,5] or even Graves disease [7] has been described. In typical Graves disease pain in the region of the thyroid is uncommon, and tenderness is at most, a minor feature.…”