Article Figures & Data
Figures
- FIGURE 1.
Sonographically suspicious left thyroid nodule in patient with normal TSH level (i.e., 1.24 mUI/L). FNA biopsy demonstrated follicular neoplasm (Bethesda IV cytology). MPUS shows slightly irregular hypoechoic nodule (A) with increased vascularization (B). 123I TS depicted AFTN (C) excluding malignancy.
- FIGURE 2.
Diagnostic work-up of thyroid nodules. Local TSH threshold is mainly based on local iodine supply: in general, levels below lower limit of reference range (i.e., <0.3–0.4 mUI/L) are adopted in countries with adequate iodine supply whereas higher values are suggested in countries with previous or current iodine deficiency (up to 2.5–3.0 mUI/L) (1,44–48).
- FIGURE 3.
Cytologically indeterminate thyroid nodules at FNA. TS demonstrates photopenic defect on 99mTc-pertechnetate scan consistent with hypofunctioning nodule within right thyroid lobe (A) with uptake and retention of 99mTc-sestaMIBI (B). Histology: papillary thyroid cancer, follicular variant.
- FIGURE 4.
Chronically fluctuating low TSH values in woman with no biologic diagnosis for autoimmune thyroid disease (i.e., negative TRAb and TPOAb) and unremarkable MPUS (not shown). (A) Baseline TS: normal 123I thyroid uptake (13.1%) and homogeneous tracer distribution. (B) Suppressed TS: not suppressed 123I thyroid uptake (9.2%) and well-contrasted thyroid image after administration of liothyronine (50 μg/d) for 5 d demonstrate diffuse thyroid autonomy.
Tables
- TABLE 1
Thyrotoxicosis: Etiology, Pathophysiology, and Relevant Points for Differential Diagnosis
Disease Etiology Pathophysiology Laboratory Thyroid scan and RAIU MPUS GD Autoimmune TSH-R stimulation TSH, fT4/fT3; TRAb+ 95%–99%; TPOAb+ ∼60% Uptake (diffuse) Hypoechoic pattern; Vascular flow (diffuse) GD variants Autoimmune Mixed GD/AITD TSH, fT4/fT3; TRAb+ 95%–99%; TPOAb+ ∼80% Uptake (heterogeneous) Hypoechoic pattern; Vascular flow (diffuse) Autoimmune GD+hypofunctioning nodule(s) TSH, fT4/fT3; TRAb+ 95%–99%; TPOAb+ ∼60% Uptake (diffuse) with cold nodule(s) Hypoechoic diffuse variable for nodules Autoimmune GD+hyperfunctioning nodule TSH, fT4/fT3; TRAb+ 95%–99%; TPOAb+ ∼60% Marine-Lenhardt syndrome Aspecific pattern TFA Somatic mutations Overactive TSH-R; overactive Gsα-subunit TSH, fT4/fT3; no specific biomarkers TSH-independent thyroid uptake Aspecific pattern TFA variants Somatic mutations Unifocal autonomy TSH, fT4/fT3; no specific biomarkers TSH-independent unifocal uptake Aspecific pattern Somatic mutations Multifocal autonomy TSH, fT4/fT3; no specific biomarkers TSH-independent multifocal uptakes Aspecific pattern Somatic mutations Disseminated autonomy TSH, fT4/fT3; no specific biomarkers TSH-independent diffuse uptake Aspecific pattern Subacute thyroiditis Viral Inflammatory destruction TSH, fT4/fT3; ESR/CRP; TPOAb+ infrequent Absent to uptake (early phase) Hypoechoic; irregular vascular flow Painless thyroiditis Autoimmune Transient immuno-mediated cytolysis TSH, fT4/fT3; TPOAb+ 95%–99%; normal ESR/CRP Absent to uptake (early phase) Hypoechoic; normal to vascular flow Drug induced Iodine overload AIH type 1: pathologic escape from Wolff-Chaickoff effect) TSH, fT4/fT3; ioduria Uptake with visible contrast Aspecific pattern Iodine overload AIH type 2: iodine-induced destructive thyroiditis TSH, fT4/fT3; ioduria Absent uptake Hypoechoic; irregular vascular flow TKI, ICPI Destructive thyroiditis TSH, fT4/fT3; TPOAb+ variable Absent to uptake Aspecific pattern Factitious thyrotoxicosis T4, T3, TH analogs TSH, fT4/fT3; thyroglobulin Absent to uptake Normal to vascular flow Tumors Struma ovarii Ovarian TH biosynthesis TSH, fT4/fT3; thyroglobulin Suppressed to uptake Normal thyroid pelvic US: ovarian tumor Thyroid cancer Functioning metastasis TSH, fT4/fT3; thyroglobulin Consider 131I-WBS (thyroid suppressed) Suspicious lymph nodes and thyroid nodules Germinal tumors βHCG overproduction TSH, fT4/fT3; βHCG Normal to diffuse uptake Normal to vascular flow Central Pituitary resistance THR mutation (TRβ) Normal to TSH; normal to fT4/fT3 Normal to diffuse uptake Normal to vascular flow Pituitary adenoma TSH-secreting tumor Normal to TSH; normal to fT4/fT3; TSH α-subunit Normal to diffuse uptake Normal to vascular flow AIH = amiodarone-induced hyperthyroidism; AITD = autoimmune thyroid diseases; CRP = C-reactive protein; ESR = erythrocyte sedimentation rate; fT3 = free triiodothyronine; fT4 = free thyroxine; GD = Graves disease; HCG = human chorionic gonadotropin; ICPI = immune checkpoint inhibitor; TFA = thyroid functional autonomy; TH = thyroid hormone; THR = thyroid hormone receptor; TKI = thyrosine kinase inhibitors; TPOAb = thyroperoxidase antibody; TRAb = TSH-receptor antibody; TRβ = thyroid receptor β; TSH = thyroid stimulating hormone; TSH-R = TSH-receptor; T4 = thyroxine; T3 = liothyronine; US = ultrasound; WBS = whole-body scintigraphy.
