Understanding thyroid function disorders

* INCLUSION CRITERIA:

The categories of subjects eligible to participate in this study include:

1. Participants with known or suspected thyroid abnormalities (e.g. hypothyroidism, hyperthyroidism, extreme iodine deficiency, and inherited forms of hypothyroidism resulting from abnormalities in the expression of genes coding for the TSH- beta subunit, Pax-8, TTF-2, Pit-I, Tg, PDS, and NIS).
2. Participants with thyroid function test (TFT) abnormalities due to:

   * Non-thyroidal illness
   * Abnormalities of serum TH binding proteins leading to euthyroid hyperthyroxinemia or hypotriiodothyronemia.
   * Genetic deficiency of thyroxine-binding globulin (TBG).
   * Antibodies to mouse immunoglobulins leading to an artifactual elevation in the TSH ultrasensitive ("3rd generation") assay which may mimic "inappropriate" secretion of TSH.

Inclusion and exclusion criteria for each group of subjects are given below.

Participants with known or suspected thyroid abnormalities will be eligible to participate if the individual meets all of the following criteria:

1. Stated willingness to comply with all study procedures and availability for the duration of the study.
2. Male or female, aged 6 months+.

Hyperthyroid states include but are not restricted to:

1. Graves' disease (GD) thought to result from thyroid-stimulating immunoglobulins (TSIg's), a subclass of which also stimulate eye muscle and fatty tissue producing exophthalmos (Graves' ophthalmopathy), as well as the skin in the pretibial area causing pretibial myxedema (Graves' dermopathy);
2. Subacute thyroiditis (SAT), a painful inflammation thought to result from viral infection with Coxsackie, as well as other viruses;
3. Silent thyroiditis, a painless inflammation thought to result from autoimmune attack of thyrocytes by antimicrosomal antibodies directed against thyroid peroxidase (TPO), as well as antithyroglobulin(anti-Tg) antibodies;
4. Single or multiple hyperfunctioning thyroid nodules of unknown etiology, probably resulting from the activation of certain thyroid oncogenes and/or growth factors, such as the thyrotropin (TSH) receptor (TSHR) and the a-subunit of the Gs protein (Gsa);
5. Iodide-induced hyperthyroidism of unknown etiology;
6. Surreptitious administration of thyroid hormone (TH), usually present in participants with underlying psychiatric disease or occasionally related to participants with obesity and other eating disorders
7. Trophoblastic neoplasms, thought to result from high levels of hCG secretion, which, because of its structural similarity to TSH, causes "spillover" of action at the TSHR level;
8. "Inappropriate" secretion of TSH, which may be present either in participants with TSH- producing pituitary tumors (TSHomas) or from a non-neoplastic cause, i.e. pituitary resistance to the action of thyroid hormone (3,4).

The above are the principal variants of hyperthyroidism that we will study, although we may discover that certain participants may turn out to have rare causes of hyperthyroidism, e.g. unusual variants of ectopic thyroid tissue, "hyperfunctioning" thyroid cancer, choriocarcinoma, or ovarian teratomas. Finally, some participants may present with extreme thyrotoxic symptoms in the context of "thyroid storm" or, conversely, with apathetic thyrotoxicosis.

Hypothyroid states include but are not restricted to:

1. Primary (or thyroidal) hypothyroidism, usually resulting from auto-antibodies to thyroid proteins, such as antimicrosomal antibodies to TPO usually associated with lymphocytic (Hashimoto's) thyroiditis (HT) or atrophic thyroiditis, or blocking antibodies to the TSHR, usually in the context of non-goitrous hypothyroidism;
2. Secondary (or pituitary) hypothyroidism, usually resulting from tumors of the pituitary of non-thyrotropic origin such, as growth hormone (GH)-secreting tumors or prolactinomas;
3. Tertiary (or hypothalamic) hypothyroidism, usually resulting from a deficiency in the hypothalamic hormone thyrotropin-releasing hormone (TRH), either of unknown etiology or secondary to a pituitary tumor;
4. Bio-inactive TSH, either relating to an endogenous abnormality of hypothalamic hormones or secondary to pituitary tumors (and usually related to abnormal glycosylation patterns of the TSH molecule);
5. Generalized resistance to thyroid hormone (RTH), a disease which has been shown to be due to abnormalities in the TH receptor, c-erbA-beta (or TR- beta).

The above are the principal disorders under study, but we may also investigate other abnormalities, such as extreme iodine deficiency, and inherited forms of hypothyroidism resulting from abnormalities in the expression of genes coding for the TSH- beta subunit, Pax-8, TTF-2, Pit-I, Tg, PDS, and NIS (among others).

EXCLUSION CRITERIA:

There are no exclusion criteria for subjects with known or suspected thyroid abnormalities.