Search

Thyrotropin (TSH)-secreting pituitary adenoma (TSHoma) and resistance to thyroid hormone (RTH) are two forms of inappropriate TSH secretion. Thyroid blood flow is largely TSH dependent.To assess whether thyroid blood flow may help to differentiate TSHoma and RTH.Intrathyroidal color flow Doppler sonography (CFDS) pattern and peak systolic velocity (PSV) were assessed at baseline and during T(3) suppression test on eight consecutive patients with TSHoma and 10 with RTH.All controls had CFDS pattern 0. Three RTH patients had pattern I and seven had pattern II. Two TSHoma patients had pattern I, five had pattern II, and one had pattern III. PSV at baseline was 3.8 +/- 1.3 cm/s in controls, 8.8 +/- 2.5 cm/s in RTH, 11.1 +/- 2.7 cm/s in TSHoma (p0.0003 vs. controls, p = 0.087 RTH vs. TSHoma). After T3 suppression test, PSV values were lower in RTH than in TSHoma (4.6 +/- 1.8 vs. 7.7 +/- 2.6 cm/s, p = 0.008). PSV values and CFDS pattern normalized in nine and eight RTH patients, respectively, after T(3) suppression test; conversely, only one TSHoma patient had a normalization of PSV values, and none had a normalization of CFDS pattern (p0.003 vs. RTH).Both RTH and TSHoma have increased CFDS pattern and PSV values; however, after T(3) both parameters normalized in most patients with RTH but not in those with TSHoma. Accordingly, CFDS pattern and PSV are adjunctive tools to differentiate these two forms of inappropriate TSH secretion.

Postpartum thyroid dysfunction (PPTD) is an autoimmune-mediated thyroid destructive process. Human interleukin-6 (IL-6) is a cytokine found to be increased in subacute thyroiditis, amiodarone-induced thyrotoxicosis, Graves' disease, and other thyroid destructive processes. We report serum IL-6 levels in PPTD in two independent studies. New York Study: In a previous prospective study we demonstrated that PPTD occurred in 25% (7/28) of women with type 1 diabetes mellitus. IL-6 determinations were made on the frozen serum samples of these 28 women during each trimester of their pregnancy and at 1.5, 3, 6, 9, and 12 months postpartum. IL-6 levels were found to be similar in women with PPTD compared with women without PPTD (mean 3.06+/-2.25 vs. 2.51+/-2.21 pg/mL; p = 0.15). No difference in IL-6 levels was found between the pre- and the postpartum periods (mean 2.67+/-1.82 vs. 3.04+/-2.44 pg/mL; p = 0.30) in all 28 women. Cardiff Study: Serum IL-6 levels were measured on frozen serum samples of 30 women with PPTD. IL-6 levels were below the detection limit (25 fmol/L or 0.65 pg/mL) in 94 (67%) of these samples. No significant difference in the mean serum IL-6 levels were found between any time points in the study. There was no correlation between serum IL-6 levels, thyroid peroxidase (TPO)- antibodies and serum thyrotropin (TSH) levels at any time point. IL-6 levels during pregnancy or postpartum were not found to be significantly different in women with PPTD compared with women without PPTD.

Amiodarone-induced thyrotoxicosis (AIT) occurs both in abnormal thyroid glands (nodular goiter, latent Graves' disease) (type I AIT) or in apparently normal thyroid glands (type II AIT). Differentiation of the two forms is crucial, because type I AIT responds well to methimazole and potassium perchlorate combined treatment, whereas type II AIT is effectively managed by glucocorticoids. Differential diagnosis is often difficult, although thyroid radioactive iodine uptake is usually low-to-normal in type I and low-suppressed in type II, and serum interleukin-6 levels are normal/slightly elevated in type I, markedly elevated in type II. Color flow Doppler sonography (CFDS) is a technique that shows intrathyroidal blood flow and provides real-time information on thyroid morphology and hyperfunction. To investigate the usefulness of CFDS in differentiating the two types of AIT, 27 consecutive AIT patients, 11 type I and 16 type II, were evaluated by CFDS before starting antithyroid treatment. Gender, age, severity of thyrotoxicosis, and cumulative amiodarone dose were similar in the two groups. All type II AIT patients had a CFDS pattern 0 (ie, absent vascularity), in agreement with the pathogenesis of the disease, due to thyroid damage. Likewise, nine patients with subacute thyroiditis, another destructive process of the thyroid gland, also had a CFDS pattern 0. Eleven patients with type I AIT had a CFDS pattern ranging from pattern I (presence of parenchymal blood flow with patchy uneven distribution) (7 patients, 64%) to pattern II (ie, mild increase of color flow Doppler signal with patchy distribution) (1 patient, 9%) and pattern III (markedly increased color flow Doppler signal with diffuse homogeneous distribution)(3 patients, 27%), similar to that found in patients with untreated Graves' disease patients, thus indicating a hyper-functioning gland. Control subjects and euthyroid patients under long-term amiodarone treatment had absent thyroid hypervascularity and a CFDS pattern 0. These findings demonstrate that CFDS distinguishes type I and II AIT. Because of its rapidity and noninvasive features, CFDS represents a valuable tool for a quick differentiation between the two types of AIT. This can avoid any delay in initiating the appropriate treatment for a rapid control of thyrotoxicosis in patients whose tachyarrhythmias or other cardiac disorders make thyroid hormone excess extremely deleterious.

The clinical course of 306 Graves' patients treated with methimazole (MMI) was reviewed with the aim of establishing criteria able to predict remission of hyperthyroidism after medical treatment. One hundred and ninety-four (149 females, 45 males) of 306 (63.4%) patients had relapse of hyperthyroidism after antithyroid drug (ATD) withdrawal. Relapse was more frequent during the first months of the follow-up, but still it was observed 3 years after MMI withdrawal. The relapse rate was dependent on the age of the patient, the size of goiter, and the level of TSH-receptor antibody (TRAb) at diagnosis, being observed in 40 of 47 (85%) patients with high (30 U/L) TRAb level and in 54 of 101 (53%) patients with low TRAb level (or = 30 U/L; p.0002). Remission was more frequent (43.3%) in patients having the combination goiter sizeor = 40 mL, TRAb levelor = 30 U/L, than in patients with goiter size40 mL and high TRAb levels (9%). In the subgroup of patients with the combination: goiteror = 40 mL- TRAbor = 30 U/L - age at onset40 years, the remission rate was 80%, and all relapses occurred within the first 9 months after MMI withdrawal. In conclusion, our study confirms that hyperthyroidism relapses in the majority of patients with Graves' disease treated with ATD. Among different clinical and laboratory features, age at onset of hyperthyroidism, goiter size and TRAb level are particularly helpful in identifying those patients who are more prone to undergo a remission of hyperthyroidism after medical treatment and may be useful to select the minority of Graves' patients who will benefit from antithyroid drug treatment as a first choice.