Editing Hashimoto's thyroiditis (section)

==Diagnosis==
[[File:Hashimoto-Thyreoiditis.JPG|thumb|Ultrasound imaging of the thyroid gland (right lobe longitudinal) in a person with Hashimoto thyroiditis]]

=== Tests ===
==== Physical exam ====
Physicians will often start by assessing reported symptoms and performing a thorough physical exam, including a neck exam.<ref name="Mincer2022" /> Patients may have a "firm, bumpy, symmetric, painless goiter", however, up to 10% of patients may have an [[Atrophy|atrophied]] thyroid.<ref name="Ramos-Levi2023" />

==== Antithyroid antibodies tests====
Tests for [[antibodies]] against [[thyroid peroxidase]], [[thyroglobulin]], and [[thyrotropin receptor]]s can detect autoimmune processes against the thyroid. 90% of hashimoto's patients have elevated levels of thyroid peroxidase antibodies.<ref name="Ramos-Levi2023" /> However, seronegative (without circulating autoantibodies) thyroiditis is also possible.<ref>{{cite journal | vauthors = Grani G, Carbotta G, Nesca A, D'Alessandri M, Vitale M, Del Sordo M, Fumarola A | title = A comprehensive score to diagnose Hashimoto's thyroiditis: a proposal | journal = Endocrine | volume = 49 | issue = 2 | pages = 361–365 | date = June 2015 | pmid = 25280964 | doi = 10.1007/s12020-014-0441-5 | s2cid = 23026213 }}</ref> There may be circulating antibodies before the onset of any symptoms.<ref name="Mincer2022" />

==== Ultrasound ====
[[File:Hashimoto Thyroiditis.jpg|thumb|Ultrasound imaging of the thyroid showing Hashimoto's thyroiditis]]
An [[ultrasound]] may be useful in detecting Hashimoto thyroiditis, especially in those with seronegative thyroiditis,<ref name="Klubo-Gwiezdzinska-2022" /> or when patients have normal laboratory values but symptoms of autoimmune thyroiditis.<ref name="Niddk2021" />  Key features detected in the ultrasound of a person with Hashimoto's thyroiditis include "[[echogenicity]], [[Homogeneity and heterogeneity|heterogeneity]], [[hypervascularity]], and presence of small [[Thyroid nodule|cysts]]."<ref name="Klubo-Gwiezdzinska-2022" /> Images obtained with ultrasound can evaluate the size of the thyroid, reveal the presence of nodules, or provide clues to the diagnosis of other thyroid conditions.<ref name="Niddk2021" />

==== Nuclear medicine ====
[[Nuclear imaging]] showing thyroid uptake can also be helpful in diagnosing thyroid function, particularly differential diagnosis.<ref name="Ramos-Levi2023" />

==== TSH levels test ====
Elevated [[Thyroid-stimulating hormone]] (TSH) levels may indicate [[hypothyroidism]] (underpeforming thyroid).<ref name="Niddk2021"/> Hypothyroidism is a common symptom and potential indication of Hashimoto's disease.<ref name="Ramos-Levi2023" /> As blood levels of thyroid hormones fall due to hypothyroidism, the anterior [[Pituitary gland|pituitary]] gland increases production of TSH, which stimulates increased production of thyroid hormones in the thyroid.<ref name=":6" /> The elevation is usually a marked increase over the normal range.<ref name="Singh2020"/> TSH is the preferred initial test of thyroid function as it has a higher [[Sensitivity and specificity|sensitivity]] to changes in thyroid status than free T<sub>4</sub>.<ref>{{Cite book | author = Royal College of Pathologists of Australasia | chapter = Thyroid stimulating hormone | chapter-url = https://www.rcpa.edu.au/Manuals/RCPA-Manual/Pathology-Tests/T/Thyroid-stimulating-hormone | title = Royal College of Pathologists of Australasia Manual }}</ref>

Biotin can cause this test to read "falsely low".<ref name=":6" /> Time of day can affect the results of this test; TSH peaks early in the morning and slumps in the late afternoon to early evening,<ref>{{cite journal | vauthors = Ikegami K, Refetoff S, Van Cauter E, Yoshimura T | title = Interconnection between circadian clocks and thyroid function | journal = Nature Reviews. Endocrinology | volume = 15 | issue = 10 | pages = 590–600 | date = October 2019 | pmid = 31406343 | pmc = 7288350 | doi = 10.1038/s41574-019-0237-z }}</ref> with "a variation in TSH by a mean of between 0.95 m[[International unit|IU]]/mL to 2.0 mIU/mL".<ref>{{cite journal | vauthors = Sheehan MT | title = Biochemical Testing of the Thyroid: TSH is the Best and, Oftentimes, Only Test Needed - A Review for Primary Care | journal = Clinical Medicine & Research | volume = 14 | issue = 2 | pages = 83–92 | date = June 2016 | pmid = 27231117 | pmc = 5321289 | doi = 10.3121/cmr.2016.1309 }}</ref> Hypothyroidism is diagnosed more often in samples taken soon after waking.<ref>{{cite journal | vauthors = Sviridonova MA, Fadeyev VV, Sych YP, Melnichenko GA | title = Clinical significance of TSH circadian variability in patients with hypothyroidism | journal = Endocrine Research | volume = 38 | issue = 1 | pages = 24–31 | date = 2013-05-01 | pmid = 22857384 | doi = 10.3109/07435800.2012.710696 }}</ref>   

==== T<sub>3</sub> or T<sub>4</sub> levels test ====
These tests detect levels of two thyroid hormones: [[Thyroxine]] ([[Thyroxine|T<sub>4</sub>]]) and [[Triiodothyronine|Tri-iodothyronine]] ([[Triiodothyronine|T<sub>3</sub>]]). Low levels of these hormones (hypothyroidism) may indicate autoimmune damage to the thyroid due to Hashimoto's, while elevated levels may indicate an attack of destructive thyrotoxicosis.<ref name="Ramos-Levi2023" /> Hashimotos with normal levels is possible however.

Free or total levels can be measured. Typically, Free T<sub>4</sub> is the preferred test for hypothyroidism,<ref name="Van Uytfanghe-2023">{{cite journal | vauthors = Van Uytfanghe K, Ehrenkranz J, Halsall D, Hoff K, Loh TP, Spencer CA, Köhrle J | title = Thyroid Stimulating Hormone and Thyroid Hormones (Triiodothyronine and Thyroxine): An American Thyroid Association-Commissioned Review of Current Clinical and Laboratory Status | journal = Thyroid | volume = 33 | issue = 9 | pages = 1013–1028 | date = September 2023 | pmid = 37655789 | pmc = 10517335 | doi = 10.1089/thy.2023.0169 }}</ref> as Free T<sub>3</sub> [[Immunoassay|immunoassay tests]] are less reliable at detecting low levels of thyroid hormone,<ref>{{Cite book | author = Royal College of Pathologists of Australasia | chapter = Free T3 | chapter-url=https://www.rcpa.edu.au/Manuals/RCPA-Manual/Pathology-Tests/F/Free-T3 | title = Royal College of Pathologists of Australasia Manual}}</ref> and they are more susceptible to interference.<ref name="Van Uytfanghe-2023" /> Both immunoassay tests of Free T<sub>4</sub> and Free T<sub>3</sub> may overestimate concentrations, particularly at low thyroid hormone levels, which is why results are typically read in conjunction with TSH, a more sensitive measure.<ref name="Welsh-2016">{{cite journal |vauthors=Welsh KJ, Soldin SJ |date=December 2016 |title=DIAGNOSIS OF ENDOCRINE DISEASE: How reliable are free thyroid and total T3 hormone assays? |journal=European Journal of Endocrinology |volume=175 |issue=6 |pages=R255–R263 |doi=10.1530/EJE-16-0193 |pmc=5113291 |pmid=27737898}}</ref> [[Liquid chromatography–mass spectrometry|LC-MSMS]] assays are rarer, but they are "highly specific, sensitive, precise, and can detect hormones found in low concentrations."<ref name="Welsh-2016" />

==== Muscle Biopsy ====
Muscle [[biopsy]] is not necessary for diagnosis of [[myopathy]] due to hypothyroid [[Skeletal muscle#Fiber types|muscle fibre]] changes, however it may reveal confirmatory features.<ref name="Fariduddin-2024" />