Edgepedia

Thyrididae

Thyrididae, window-winged moths (Thyridoidea), a tropical family of about 940 moth species with translucent wing patches, dead-leaf mimicry, and stem-boring or leaf-tying larvae.

Thyristor

A thyristor, best known as the silicon controlled rectifier introduced by General Electric in 1957, is a four-layer semiconductor switch that latches on when a gate pulse triggers it.

Thyristor valve

A thyristor valve is the complete engineered assembly of series-connected thyristors with gating, grading, and cooling that performs one switching function in an HVDC converter station.

Thyristor-controlled reactor

A thyristor-controlled reactor (TCR) is a shunt inductor in series with back-to-back thyristors, whose current is varied continuously and forms the core of most static var compensators.

Thyristor-controlled series capacitor

A thyristor-controlled series capacitor (TCSC) is a series-connected FACTS device that varies the reactance of an AC transmission line, used for power flow control, damping power oscillations, and mitigating subsynchronous resonance.

Thyristor-switched capacitor

A thyristor-switched capacitor (TSC) is a shunt capacitor bank switched fully on or off by a bidirectional thyristor valve, giving fast, near-transient-free reactive power control in static var compensators.

Sep 19, 2026

Thyrocare Technologies

Thyrocare Technologies is an Indian diagnostics company headquartered in Navi Mumbai, founded in 1996 by A. Velumani, which listed in 2016 and sold control to PharmEasy's parent in 2021.

Thyroglobulin

Thyroglobulin (Tg), the ~660 kDa thyroid glycoprotein precursor of T4 and T3, stores iodine and thyroid hormone in follicular colloid and serves as the serum tumor marker for differentiated thyroid cancer follow-up.

Thyroid

Thyroid: butterfly-shaped endocrine gland in the neck producing T4 and T3 under TSH control; depends on iodine; hypothyroidism affects about 4.6% of Americans age 12 and older.

Thyroid cancer

Thyroid cancer: malignancy of the thyroid gland with four main types (papillary, follicular, medullary, anaplastic). About 44,020 US cases in 2025; papillary and follicular forms are usually curable, anaplastic is nearly always fatal.

Thyroid disease

Thyroid disease: group of disorders of the butterfly-shaped neck gland, including hypothyroidism (Hashimoto's), hyperthyroidism (Graves'), nodules, and cancer; diagnosed mainly by TSH blood tests.

Thyroid ectopia

Thyroid ectopia (ectopic thyroid, lingual thyroid): a developmental anomaly with thyroid tissue outside the anterior neck, most often at the tongue base; causes about two-thirds of thyroid dysgenesis and congenital hypothyroidism, female predominance 2:1.

Sep 29, 2026

Thyroid feedback quantile-based index

The thyroid feedback quantile-based index (TFQI) is a calculated measure of impaired pituitary sensitivity to free thyroxine, proposed in Diabetes Care in 2018 and ranging from −1 to 1.

Thyroid follicular cell

Thyroid follicular cell (thyrocyte): endoderm-derived epithelial cell lining thyroid follicles; uses NIS, TPO, and thyroglobulin to make T3 and T4 under TSH control; source of papillary, follicular, and anaplastic thyroid cancers.

Thyroid function tests

Thyroid function tests (TFTs) are blood tests measuring TSH, free T4, and free T3 to diagnose and monitor thyroid disorders; TSH is the first-line test, with reflex free T4 added when TSH is abnormal.

Thyroid hemiagenesis

Thyroid hemiagenesis (THA, ORPHA:95719) is a rare congenital absence of one thyroid lobe, usually the left (about 80% of cases), affecting roughly 0.02–0.2% of people, more often females, and usually asymptomatic.

Oct 20, 2026

Thyroid hormone receptor

Thyroid hormone receptor (TR, TRα/TRβ, THRA/THRB): nuclear T3-activated transcription factor binding DNA as RXR heterodimer on TREs; cloned 1986, structure 1995; TRβ mutations cause RTH.

Thyroid hormones

Thyroid hormones: T4 (thyroxine) and T3 (triiodothyronine), iodine-containing hormones from the thyroid gland regulating metabolism, growth, and brain development, activated locally by deiodinases and replaced clinically with levothyroxine.

Thyroid hypoplasia

Thyroid hypoplasia (congenital thyroid hypoplasia) is incomplete development of the thyroid gland in newborns, one form of thyroid dysgenesis causing permanent congenital hypothyroidism, usually sporadic, detected by newborn screening and treated with levothyroxine.

Thyroid lymphoma

Thyroid lymphoma is a rare B-cell non-Hodgkin lymphoma arising in the thyroid gland, accounting for about 1% to 5% of thyroid cancers and usually occurring in older women.

Thyroid nodule

Thyroid nodule: an abnormal lump of thyroid cells within the thyroid gland, found in about half of people by age 60 and over 90% benign; evaluated by ultrasound risk systems (TI-RADS) and fine-needle aspiration.

Thyroid peroxidase

Thyroid peroxidase (TPO), the thyroid microsomal antigen, is a heme enzyme on the apical membrane of thyroid follicular cells that oxidizes iodide, iodinates thyroglobulin, and couples MIT/DIT to make T3 and T4; target of antithyroid drugs and autoantigen in Hashimoto's disease.

Thyroid stimulating hormone deficiency

Thyroid stimulating hormone deficiency (ICD-11 5A61.4), also called central hypothyroidism: low TSH or TRH causing secondary/tertiary hypothyroidism, low FT4 with inappropriately normal TSH, treated with levothyroxine.

Thyroid storm

Thyroid storm (thyrotoxic crisis) is life-threatening decompensated thyrotoxicosis, usually in Graves' disease, diagnosed clinically via Burch-Wartofsky and JTA criteria and treated in the ICU with beta-blockers, thionamides, iodide, and steroids.

Thyroid-stimulating hormone

Thyroid-stimulating hormone (TSH, thyrotropin) is an anterior pituitary glycoprotein hormone that drives thyroid T4/T3 secretion via the TSH receptor; its log-linear feedback makes it the frontline thyroid test, with pregnancy and biotin interference as key caveats.

Thyroidectomy

Thyroidectomy, surgical removal of all or part of the thyroid gland; types include total, lobectomy, isthmusectomy. Used for thyroid cancer, goiter, Graves' disease; main risks are hypocalcemia and recurrent laryngeal nerve injury.

Thyroiditis

Thyroiditis, inflammation of the thyroid gland, covers Hashimoto's, subacute (de Quervain's), painless, postpartum, drug-induced, radiation-induced, and suppurative forms, with courses ranging from transient thyrotoxicosis-hypothyroidism to permanent hypothyroidism.