potassium-perchlorate and Thyroiditis

Amiodarone is an iodine-rich drug. Its chronic administration may lead to disturbances in thyroid hormone metabolism and/or overt gland dysfunction. It causes an increased in serum fT4, rT3, and TSH concentrations and a decreased serum level of fT3 without thyroid dysfunction. Amiodarone may induce thyrotoxicosis (AIT--Amiodarone-induced thyrotoxicosis) or hypothyroidism (AIH--Amiodarone-induced hypothyroidism) in some persons. AIT occurs more frequently in areas with low iodine intake. The excess iodine contributes to excessive thyroid hormone synthesis-type I AIT or may lead to thyroiditis and a destructive process of thyroid follicular cells, resulting in excess thyroid hormone release-type II AIT. The mixed form of AIT also occurs. Type I AIT should be treated with antithyroid drugs alone or in association with potassium perchlorate, type II AIT benefits from treatment with glucocorticoids, whereas the mixed form of AIT is most effectively treated with a combination of thionamides, potassium perchlorate, and glucocorticoids. AIT often requires thyroidectomy after restoration of euthyroidism or radioiodine therapy, provided that 24-h thyroid radioactive iodine uptake values permit. AIH prevails in areas with high dietary iodine intake. It requires a discontinuation of amiodarone therapy and thyroid hormone (levothyroxine) replacement. It can remit spontaneously. Amiodarone and L-thyroxine therapy is also possible. Baseline thyroid function tests, thyroid antibodies, and imaging examinations such as thyroid ultrasound on initial evaluation and follow-ups every 6 months must be carefully monitored before starting amiodarone therapy.

Topics: Amiodarone; Animals; Anti-Arrhythmia Agents; Antithyroid Agents; Female; Glucocorticoids; Humans; Hypothyroidism; Perchlorates; Potassium Compounds; Pregnancy; Thyroid Gland; Thyroid Hormones; Thyroidectomy; Thyroiditis; Thyrotoxicosis

Post-partum thyroid disease occurs in 50% of anti-thyroid peroxidase (TPO) antibody positive women (detected at 16 weeks' gestation) and is characterized by a transient episode of hyper, hypo or hyper-hypothyroidism. In approximately 20% of these women the hypothyroidism is permanent. However, the extent of long-term thyroid dysfunction, possibly mediated by immune attack, in those anti-TPO Ab + ve women who have had only transient or no thyroid dysfunction during the postpartum period is not clear.. We have therefore studied the frequency of iodide organification defects by iodide perchlorate discharge testing, and of thyroid morphological abnormalities by ultrasound scanning in euthyroid women following their episode of post-partum thyroiditis (PPT).. The study group comprised 17 women with previous PPT (PPT + ve) and 12 women who had positive anti-TPO antibodies during pregnancy but who did not develop PPT (PPT - ve). Women were studied 15-47 months following their episode of PPT.. Iodide perchlorate discharge tests were positive (more than 10% discharge) in 7 (41%) PPT + ve and 5 (42%) PPT-ve subjects (P = NS). Morphological abnormalities on thyroid ultrasound were detected in 7 of 14 (50%) PPT + ve and 7 of 9 (77%) PPT - ve subjects (P = NS). There was a strong association between abnormalities of iodide organification and morphology: of 11 subjects with positive iodide perchlorate discharge tests, 10 had abnormal (positive) ultrasound scans; of 12 subjects with negative iodide perchlorate discharge tests 8 had negative ultrasound scans (P = 0.013, Fisher's exact test).. Long-term subtle defects of thyroid function and morphology are common in women with anti-TPO antibodies in pregnancy, whether or not they develop post-partum thyroiditis. The clinical significance of these findings is unclear but a continuing thyroid pathological process is suggested.

Topics: Adult; Female; Follow-Up Studies; Humans; Iodine Radioisotopes; Perchlorates; Postpartum Period; Potassium Compounds; Potassium Iodide; Pregnancy; Prospective Studies; Thyroid Function Tests; Thyroid Gland; Thyroiditis; Ultrasonography

Postpartum thyroiditis (PPT) is common and occurs in 1.7 to 16.7% of pregnant women, depending upon the study population. Most of these women develop transient hypothyroidism and thyroid function usually returns to normal. We have studied 11 euthyroid women with a previous history of PPT to determine the incidence of subtle defects in thyroid function measured by iodide-perchlorate (I-ClO4) discharge tests and TRH tests and to determine whether these women would develop iodide-induced hypothyroidism. Seven (64%) had positive I-ClO4 discharge tests and 5 (46%) had an abnormally high TSH response to TRH. Thyroid antimicrosomal and antithyroid peroxidase were positive in 8 women (73%) with a previous episode of PPT. The administration of pharmacological amounts of iodide (10 drops of saturated solution of potassium iodide daily) for 90 days to these 11 women resulted in elevated basal and TRH stimulated serum TSH concentrations in 8 (72.7%) compared to TSH values during iodide administration to women who had never been pregnant. Antimicrosomal and antithyroid peroxidase concentrations did not change during iodide administration. These findings strongly suggest that euthyroid women with a previous episode of PPT have permanent subtle defects in thyroid hormone synthesis and are inordinately prone to develop iodide-induced hypothyroidism, similar to findings previously reported in euthyroid subjects with Hashimoto's thyroiditis, with a previous episode of painful subacute thyroiditis, or previously treated with radioactive iodine or surgery for Graves' disease.

Topics: Adult; Analysis of Variance; Autoantibodies; Cohort Studies; Female; Humans; Hypothyroidism; Iodide Peroxidase; Iodine Radioisotopes; Microsomes; Perchlorates; Potassium; Potassium Compounds; Potassium Iodide; Puerperal Disorders; Thyroid Function Tests; Thyroid Gland; Thyroiditis; Thyrotropin; Thyrotropin-Releasing Hormone; Thyroxine; Triiodothyronine

Twenty-eight patients with destructive thyroiditis were followed to study the natural history of healing of thyroid gland injury. All had sequential measurements of thyroidal iodine [127I] content by fluorescent scanning (normal mean, 10.1 mg), 17 had serial serum thyroglobulin (Tg) measurements (normal, less than 21 ng/ml), and 13 had perchlorate discharge studies during the recovery phase. Seventeen patients had painful subacute thyroiditis (SAT), 9 had painless thyroiditis with thyrotoxicosis (PTT), and 2 had postpartum thyroiditis with thyrotoxicosis (PPT). Thyroidal iodine content decreased from a mean of 9.8 to a nadir of 3.8 mg in patients with SAT and from 8.5 to a nadir of 3.5 mg in patients with PTT. Mean serum Tg concentrations were highest (approximately 165 ng/ml) in both groups 1-3 months after the onset of symptoms. Abnormalities in both 127I content and Tg levels persisted for 2 or more yr in some individuals. No patient had detectable Tg antibodies by hemagglutination, but low titers were detected intermittently by sensitive RIA in 5 PTT patients. Microsomal antibodies were positive in only 1 of 16 SAT patients, but in 4 of 7 PTT patients and in both PPT patients. Three patients had positive perchlorate discharge tests (2 of 8 with SAT, 0 of 4 with PTT, and 1 of 1 with PPT). Permanent hypothyroidism occurred in 3 patients (2 with PTT; 1 with SAT and positive antibodies), but did not correlate with perchlorate results. HLA typing and serum immunoglobulin measurements were not useful for predicting the clinical course. These data indicate that several years may be necessary for complete resolution of destructive thyroiditis; many patients have evidence of thyroid injury persisting long after serum thyroid hormone and TSH levels become normal.

Topics: Adolescent; Adult; Aged; Autoantibodies; Child; Female; Hemagglutination Tests; Humans; Immunoglobulin A; Immunoglobulin G; Immunoglobulin M; Iodine; Iodine Radioisotopes; Male; Middle Aged; Perchlorates; Potassium; Potassium Compounds; Prospective Studies; Radioimmunoassay; Thyroglobulin; Thyroid Gland; Thyroid Hormones; Thyroiditis

Topics: Adolescent; Antibodies; Child; Chronic Disease; Female; Goiter, Endemic; Humans; Iodine Radioisotopes; Male; Perchlorates; Potassium; Potassium Compounds; Thyroid Gland; Thyroiditis