Single Thyroid Research Articles

Quantitative Reverse Transcription-PCR Measurement of Thyroglobulin mRNA in Peripheral Blood of Healthy Subjects

Thyroglobulin mRNA can be detected qualitatively in the peripheral blood of patients with metastatic thyroid cancer, thyroid cancer patients with residual thyroid bed uptake, and individuals with no known thyroid disease with intact thyroid glands by use of a lengthy, highly sensitive extraction technique. To improve and broaden the clinical usefulness of this assay, we developed a quantitative reverse transcription (RT)-PCR assay for thyroglobulin mRNA, using RNA recovered from whole blood with a simplified extraction technique. Whole blood was drawn from 32 healthy subjects in standard EDTA blood collection tubes. Total RNA was extracted from whole blood, using the PUREscript RNA Isolation Kit. RT-PCR using intron-spanning primers was used to quantitatively amplify thyroglobulin mRNA, using the ABI PRISM 7700 Sequence Detection System with a fluorescent-labeled, thyroglobulin-specific oligonucleotide probe. Thyroid RNA calibration curves were created using total RNA recovered from a single nondiseased thyroid gland. Qualitative RT-PCR demonstrated the presence of thyroglobulin mRNA in the whole blood sample of each healthy subject. The mean concentration of thyroglobulin mRNA detected in these subjects was 433 +/- 69 ng of total thyroid RNA per liter of whole blood (range, 26-1502 ng/L). Overall assay imprecision (CV) was 24% for five samples analyzed 10 times each in separate analytical runs on different days. Thyroglobulin mRNA can be accurately detected and quantified in peripheral blood from healthy subjects. This new quantitative technique may improve the clinical utility of circulating thyroglobulin mRNA detection in patients with thyroid disease.

Multinodular goitre presenting as a clinical single nodule: how effective is hemithyroidectomy?

Patients who present with a single thyroid nodule that requires surgery will generally undergo hemithyroidectomy. If, however, the subsequent histological examination shows unsuspected multinodular change, there is a risk of recurrence in the remain ing lobe. The aim of this study was to determine the clinical outcome in patients who have had a hemithyroidectomy for a single thyroid nodule that was shown on subsequent histopathological examination to be part of a multinodular goitre. A survey was undertaken of patients who were identified from a thyroid surgery database with the following criteria: (i) hemithyroidectomy for clinical single nodule; and (ii) multinodular change on histopathology. Main outcome measures were clinical recurrence rate, the frequency of further thyroid surgery, and the efficacy of thyroxine treatment on recurrence. In the 229 patients studied, the clinical recurrence rate was 12%. Fourteen of the 28 patients with recurrence required further surgery. Thyroxine therapy did not influence the recurrence rate. When surgery for a clinically benign single thyroid nodule is indicated, hemithyroidectomy is an adequate surgical procedure in cases where the single nodule is subsequently found to be part of a multinodular goitre. Such patients can be reassured that the chance of clinical recurrence is low. Thyroxine replacement therapy appears not to prevent recurrence.

A CASE OF GRAVES' DISEASE IN ASSOCIATION WITH HEMIAGENESIS OF THE THYROID GLAND

SUMMARY Hemiagenesis of the thyroid gland is a rare anomaly. Few cases have been reported in the world literature. We present a case of Graves' disease in association with hemiagenesis of the thyroid gland. In this case, preoperative diagnosis was difficult because of the marked hyperplasia of the single thyroid lobe and the isthmus. Preoperative diagnosis of this anomaly is important to avoid unnecessary exploration of the side where the thyroid lobe is absent and to plan for the extent of thyroid tissue excision to avoid postoperative hypothyroidism. An ultrasound scan of the neck would have been helpful in this case.

Cystic thyroid lesions in children

Background/Purpose: Cystic lesions of the thyroid encompass a wide and heterogeneous group of disease states in children, ranging from benign purely cystic entities to malignant tumors. The purpose of this study was to study both the presentation and management of cystic thyroid lesions in the pediatric population. Methods: A retrospective review of all thyroid masses, presenting between 1978 and 1996 and found to be purely or partially cystic on ultrasound examination was conducted, looking at presentation, family history, laboratory values, ultrasound scan and radionuclide imaging, and pathological and cytological evaluation. Results: Twenty-four patients (19 girls, 5 boys) aged 6 to 18 years received the diagnosis of cystic lesions of the thyroid. Of these, 23 presented with painless neck masses, 21 were clinically euthyroid, only one had a single abnormal thyroid function test, only two had mildly positive antithyroid antibody test results, and nearly 30% had a positive family history of thyroid disease. Ultrasonography showed pure cysts in five patients and mixed solid cystic lesions in 19 patients. On scintiscan, six lesions were hot, 13 were cold, three showed normal uptake, and two were mixed. Treatment included either observation, aspiration, cyst sclerosis, surgery, or combinations thereof. Pathological and cytological results included follicular adenoma (n = 9), cystic degeneration (n = 6), multinodular goiter (n = 4), carcinoma (n = 2), branchial cleft cyst (n = 1), and undetermined (n = 2). Conclusions: Thyroid cysts are often though to represent benign degenerative disease. Our study, which is the first in the literature to specifically address thyroid cysts in children, shows that ultrasound scan is useful in evaluating thyroid masses, whereas laboratory and radionuclide are of less value, and that single lesions of mixed echogeneity are likely to represent neoplasms, a significant percentage of which are malignant.

Five-year follow-up of percutaneous ethanol injection for the treatment of hyperfunctioning thyroid nodules: a study of 117 patients.

Percutaneous ethanol injection (PEI) has been suggested as an alternative to radioiodine and surgery for the treatment of autonomous thyroid nodules (ATN). In this study we have defined the long-term efficacy and safety of PEI for the treatment of ATN, and we have attempted to optimize the clinical usefulness and improve the technical approach to PEI treatment. One hundred and seventeen patients with ATN, 26 males and 91 females, aged 48 +/- 12.9 years (mean +/- SD), were offered PEI when other established treatments were refused or contraindicated. Seventy-seven patients were affected by toxic adenoma (60 with a single nodule, 17 with a multinodular goitre); 40 patients suffered from a pretoxic single nodule. Sterile 95% ethanol was administered weekly under sonographic control by a 20-22 gauge needle without anaesthesia or pharmacological sedation. During PEI treatment, 26 toxic elderly patients were treated with methimazole and propranolol. According to hormone and scintigraphic data, three possible outcomes were identified for statistical analysis: failure (persistent suppression of extra-nodular tissue uptake, along with elevated free T4 (FT4) and free T3 (FT3) and undetectable TSH levels); partial cure (normalization of FT4 and FT3 levels, with low/ undetectable TSH levels; persistent suppression of extra-nodular uptake); complete cure (normal thyroid hormone and TSH levels; restored extra-nodular uptake). The patients were followed for up to 5 years (median 2.5). PEI therapy was well tolerated by all patients. Complete cure was achieved in all pretoxic patients and in 60 (77.9%) patients with toxic adenoma, while partial cure was observed in 7 cases (9.1%) and failure in 10 (13%). PEI treatment proved similarly effective in toxic patients with a single nodule or with multinodular goitre (87 vs 88.2%, respectively). At the end of treatment, a significant shrinkage of nodule volume was observed in all patients (P = 0.0001). Toxic patients with pretreatment volume > 40 ml (n = 8) did not show a significant difference in treatment response rate as compared to those with volume < 40 ml. Recurrence of hyperthyroidism was never observed during follow-up, independently of thyroid status before treatment. Only one patient with significant thyroid autoantibody serum levels before PEI treatment, developed sub-clinical hypothyroidism at 3 years. The administration of methimazole and/or propranolol did not modify PEI outcome. Our data confirm the efficacy and safety of percutaneous ethanol injection for the therapy of autonomous thyroid nodules. The very low incidence of hypothyroidism along with the absence of recurrence of hyperthyroidism suggests that percutaneous ethanol injection is the treatment of choice in patients with pretoxic thyroid adenoma. Percutaneous ethanol injection appears an effective alternative procedure in toxic patients with a high surgical risk even if they have large nodules, and in younger ones in whom radioiodine is contraindicated. Patients may be submitted to anti-thyroid drug and/or beta-blocker therapy if it is necessary, but this does not affect percutaneous ethanol injection treatment outcome. Finally, not only single autonomous thyroid nodules but also toxic multinodular goitre may be successfully treated by percutaneous ethanol injection.

Transcription of the rat sarcoplasmic reticulum Ca2+ adenosine triphosphatase gene is increased by 3,5,3'-triiodothyronine receptor isoform-specific interactions with the myocyte-specific enhancer factor-2a.

Thyroid hormone (T3) increases the transcription of the sarcoplasmic reticulum Ca2+ adenosine triphosphatase (ATPase) gene (SERCA 2) through three thyroid hormone response elements. The existence of repetitive cis elements with different configurations is likely to serve specific functions such as interactions with nuclear transcription factors. In addition, the presence of different T3 receptor isoforms (T3Rs) may contribute to another level of complexity in providing specificity for T3 action. In this study, we investigated T3R alpha 1-vs. T3R beta 1-specific interactions with the myocyte enhancer-specific factor-2 (MEF-2) on the expression of the SERCA 2 gene in transient transfection assays in embryonal heart-derived H9c2 cells. MEF-2a in combination with either T3R alpha 1 or T3R beta 1 isoforms resulted in a 2.5-fold increase in SERCA 2 transgene expression in the absence of T3. Addition of T3 did not induce any further increase in SERCA 2 expression when T3R alpha 1 and MEF-2a expression vectors were cotransfected. In contrast, in the presence of T3R beta 1 and MEF-2, the addition of T3 increased chlorampenicol acetyltransferase activity by an additional 2.2-fold to a total 5.5-fold increase. The interaction between MEF-2a and T3R is transcription factor specific because another factor that binds to MEF-2 consensus sites (heart factor 1b) was not able to interact with T3R. In addition, MEF-2a failed to interact with other nuclear factors (cAMP response element-binding protein and Egr-1) that stimulate SERCA 2 gene transcription. In addition, we found that a single homologous thyroid hormone response element is not able to mediate the interactions between MEF-2a and T3Rs to increase SERCA 2 gene transcription. Our findings point to T3R isoform-specific interactions with a cell type-specific transcription factor (MEF-2) in the regulation of SERCA 2 gene expression.

Thyroid nodules in childhood and adolescence--thirty years of experience.

In the thirty year period between 1966 and 1996, fifty-two patients underwent surgery for thyroid nodules at the Royal Children's Hospital, Melbourne. We aimed to review their presentation, investigation, histology, treatment and to follow up those who had malignant neoplasms. Forty-one of the fifty-two patients presented with a single thyroid nodule. Investigations performed included thyroid function tests (N = 32), thyroid autoantibodies (N = 21), an ultrasound of the thyroid (N = 26) and 99mTechnetium scanning (N = 32). Thirty-five of the neoplasms were benign, the follicular adenoma (N = 16) being the most common. Seventeen patients had malignant neoplasms, seven of whom had papillary and seven of whom had follicular carcinoma. Three patients had medullary carcinoma of the thyroid. Nine of the seventeen patients with thyroid malignancy received post-operative 131I treatment. At the time of this review, all patients were living.

Double minutes in the papillary thyroid cancer cell line PTC-1113A

The cell line PTC-1113A was established from a metastasizing recurrent papillary thyroid cancer. The cell line was growing as monolayer and showed a complex karyotype with chromosome numbers ranging from 30 to 140/metaphase. A proportion of metaphases contained double minutes and/or pulverized chromosomes. Extrachromosomal DNA seemed to originate from a B-group chromosome. A chromosome 4 painting probe hybridized to extrachromosomal material, representing double minutes (dmin) and possibly minutes. In addition, fluorescence in situ hybridization (FISH) with the chromosome 4 library detected a translocation chromosome and a pulverized chromosome originating from chromosome 4. PTC-1113A is, to our knowledge, the single papillary thyroid cancer cell line demonstrating evidence of gene amplification.

An adenosine derivative cooperates with TSH and Graves' IgG to induce Ca 2+ mobilization in single human thyroid cells

Digital video imaging indicated that about 80% of fura-2-loaded single human thyroid cells responded to TSH, resulting in an increase in intracellular Ca 2+ concentration ([Ca 2+] i). Most of the TSH-sensitive cells further responded to N 6-( l-2-phenylisopropyl)-adenosine (PIA) showing a transient [Ca 2+] i rise in a PIA dose-dependent manner. Addition of PIA prior to TSH administration had no effect or showed only a slight [Ca 2+] i increase, but in about 80% of the cells, regardless of the response to PIA, the addition of TSH after PIA resulted in a higher transient [Ca 2+] i response than that in the absence of PIA. Inactivation of G i G 0 by pertussis toxin (PTX) treatment markedly reduced the effect of PIA on TSH action to the level induced by PIA alone. Immunoglobulin fractions obtained from two Graves' patients with high TSAb (antibody activity measured by cAMP response) activity induced [Ca 2+] i increase and cooperated with PIA. Under the same conditions, TSH-dependent cAMP accumulation was inhibited by PIA. These results suggest that adenosine A 1 receptor is expressed in human thyroid cells in primary culture as well as in FRTL-5 rat thyroid cells, and that in the presence of adenosine, TSH or Graves' IgG signal tends to be directed to the Ca 2+ pathway in the human thyroid.

Microfluorometric kinetic analysis of cathepsin B activity in single human thyroid follicular epithelial cells using image analysis and continuous monitoring.

The activity of a cysteine proteinase, cathepsin B (EC 3.4.22.1), was determined in unfixed single human thyroid follicular epithelial cells at room temperature using an image analysis system. The formation of the reaction product was monitored every minute by measuring the increasing fluorescence intensity of emitted light from a Schiff-base product formed by the substrate N-CBZ-ala-arg-arg-4-methoxy-2-naphthylamide and the coupling agent 5-nitrosalicylaldehyde. Non-specific fluorescent signals were eliminated by adjusting the video signal to zero using leupeptin, a specific inhibitor of cathepsins B, H and L. The enzyme activity was expressed as fluorescence intensity versus time. After a mean lag period of 5 min (range 4-8 min, n = 4), the enzyme activity increased linearly lasting on average 5 min (range 3-8 min), followed by a marked decrease in reaction rate for 3 min (range 1-4 min), and another linear increase for 11 min (range 8-14 min). The second linear part of the curve was not as steep as the first one. The reaction velocity recorded in individual granules resulted either in a biphasic curve or straight line, suggesting the presence of two distinct organelle compartments with differences in membrane permeability. It is concluded that human thyroid follicular epithelial cells in culture exhibit cathepsin B activity which can be monitored continuously by videomicrofluorometry without interference from non-specific fluorescence.

The arterial anatomy of larynx transplantation: Microsurgical revascularization of the larynx

Advances in immunosuppression and selective reinnervation may soon make laryngeal transplantation a potential therapy for patients undergoing total laryngectomy. Successful transplantation requires a clear delineation of those vessels necessary to completely revascularize the larynx. Our hypothesis is that the arterial inflow provided by a single superior thyroid artery is sufficient to revascularize the entire larynx. To test this hypothesis, 8 cadavers were studied via either barium latex injection (n = 4) to assess contralateral tissue perfusion or India ink (n = 4), to determine the degree of mucosal perfusion. Following injection via a single superior thyroid artery, all larynges demonstrated either complete, bilateral tissue perfusion evidenced by x-ray visualization of the barium latex injected specimen or bilateral mucosal staining with India ink. We conclude that bilateral perfusion of the entire larynx transplant, including laryngeal and epiglottic mucosa, would occur after revascularization of a single superior thyroid artery. These findings suggest that reliable revascularization of a larynx transplant is technically possible using modern microsurgical techniques.

Levothyroxine suppressive therapy for solitary thyroid nodule.

In order to evaluate the efficacy of a TSH suppressive dose of levothyroxine to reduce the volume of a single thyroid nodule we studied 55 euthyroid patient: 45 (group A) were suppressed with LT4 (mean 1.7 +/- 0.9 micrograms/Kg/day) for 21.3 +/- 5.3 months, and 10 patients (group B) served as controls. All the nodules were "cold" at scintiscanning, solid at ultrasonography and benign by fine-needle aspiration cytology. As responders were assumed the nodules shrinked at the end of treatment of 50% in volume. Thyroid function values (TSH, T4, FT4, T3, FT3, thyroid peroxidase and thyroglobulin antibodies), clinical and ultrasonographic findings were evaluated initially and at the end of the study. A significant nodular volume decrease occurred in 8 treated patients (17.8%) while 37 (82.2%) amongst the group suppressed and all controls showed no change (A vs B = NS). In two untreated patients new nodules were noted; no new nodules were discovered in the treated group (A vs B p < 005). No side effects occurred in any treated patient, even if at the end of treatment a significant T4 and FT4 (p < 0.01) increase was observed. No one onset parameter can predict the response to the therapy. These results suggest that only a small group of patients affected by a single thyroid nodule seems to respond to a TSH suppressive therapy.

Papillary thyroid carcinoma arising in thyroglossal duct cysts: incidence and management.

The incidence and pathological features of papillary thyroid carcinoma arising in the thyroglossal duct cysts were reviewed and compared with papillary thyroid carcinoma arising elsewhere in the thyroid gland. In the 30 year period 1964 to 1993 there were 90 thyroglossal duct nodules or cysts treated surgically at the Endocrine Surgical Unit, Royal North Shore Hospital, Sydney, Australia. There were four cases of papillary thyroid carcinoma in this group (4.4%). In the same period 2814 cases presented with clinical single thyroid nodules which were treated surgically. There were 182 cancers in this group of which 121 were papillary thyroid carcinomas (4.3% of total cases). This is identical to the incidence seen in the thyroglossal duct. We conclude that the incidence of papillary thyroid carcinoma arising in the thyroglossal duct is no different to that arising elsewhere in the gland. The difference in number of carcinomas related only to the volume of follicular thyroid tissue present in the gland proper. That being the case, there is no reason to treat these cancers differently from papillary thyroid carcinoma elsewhere in the gland.

Single strand DNA-binding proteins and thyroid transcription factor-1 conjointly regulate thyrotropin receptor gene expression

Single strand DNA-binding proteins and thyroid transcription factor-1 conjointly regulate thyrotropin receptor gene expression

Single strand DNA-binding proteins and thyroid transcription factor-1 conjointly regulate thyrotropin receptor gene expression.

An element, -186 to -176 base pairs (bp), in the minimal TSH receptor (TSHR) promoter binds thyroid transcription factor-1 (TTF-1) and is important for both constitutive expression and TSH/cAMP-induced negative autoregulation of the TSHR in thyroid cells. An element on the noncoding strand of the TSHR, contiguous with the 5'-end of the TTF-1 element, has single strand binding activity. It is distinct from the TTF-1 site, as evidenced by competition experiments using gel shift assays; but the association of the two elements is not random. Thus, the single strand binding protein (SSBP) element also exists contiguous to the 5'-end of an upstream TTF-1 site, -881 to -866 bp; mutation of two conserved nucleotides in each SSBP element results in the loss of SSBP binding and cross-competition. Transfection experiments indicate that full, constitutive TSHR gene expression in FRTL-5 thyroid cells requires the binding of both SSBPs and TTF-1, since mutation of either element halves thyroid-specific promoter activity, whereas mutation of both decreases promoter activity to values near those of a control vector. Transfection experiments with rat liver cells support their independent activities and show that the SSBP site contributes to TSHR gene expression in non-thyroid tissue. The SSBPs function conjointly with TTF-1 in thyroid-specific, TSH/cAMP-induced negative autoregulation of the TSHR. Thus, TSH or forskolin-treated FRTL-5 cells coordinately decrease TSHR RNA levels and TSHR DNA binding to both the SSBPs and TTF-1; also the maximal TSH/cAMP-induced decrease in gene expression requires both elements. The TSH-induced effect in each case is inhibited by cycloheximide; the TSH-induced decrease in SSBP/DNA complex formation requires the presence of insulin or calf serum, exactly as does TSH-induced down-regulation of TSHR RNA levels. In sum, full, constitutive expression of the TSHR in thyroid cells requires TTF-1 and the SSBPs to bind separate, contiguous elements on the TSHR promoter. TSH/cAMP decreases the binding of each factor to its respective site, thereby decreasing TSHR gene expression. The role of the SSBP and TTF-1 sites in constitutive TSHR expression and in TSH/cAMP-induced negative regulation of the TSHR is, therefore, additive and independent.

Cooperation of thyrotropin, but not basic fibroblast growth factor, with an adenosine receptor agonist in Ca2+ mobilization from thapsigargin-sensitive pools in single FRTL-5 thyroid cells.

TSH-induced intracellular Ca2+ concentration ([Ca2+]i) changes in single FRTL-5 thyroid cells were analyzed by digital video imaging of fura-2-loaded cells. More than 80% of the cells responded to as little as 30 nM TSH, resulting in a [Ca2+]i rise in the presence and absence of extracellular Ca2+. One micromolar concentration of N6-(L-2-phenylisopropyl)adenosine (PIA) caused no appreciable [Ca2+]i increase in more than 300 cells examined, but induced the [Ca2+]i elevation in more than 90% of the cells that had previously been treated with TSH. Pertussis toxin treatment abolished the PIA, but not the TSH, action, whereas thapsigargin-induced Ca2+ depletion of the inositol 1,4,5-trisphosphate-sensitive pool inhibited the actions of both TSH and PIA. The time courses of Ca2+ response considerably differentiated among single cells, but showed similarity among different areas in each cell. These results suggest that PIA induces Ca2+ release from the same thapsigargin-sensitive pool as that targeted by TSH. The lack of PIA stimulation of basic fibroblast growth factor-induced phospholipase-C gamma activation as well as the rise in [Ca2+]i suggests that the cooperative PIA action occurs specifically on phospholipase-C beta.

Cooperation of thyrotropin, but not basic fibroblast growth factor, with an adenosine receptor agonist in Ca2+ mobilization from thapsigargin-sensitive pools in single FRTL-5 thyroid cells

Cooperation of thyrotropin, but not basic fibroblast growth factor, with an adenosine receptor agonist in Ca2+ mobilization from thapsigargin-sensitive pools in single FRTL-5 thyroid cells

Cold thyroid nodules: a new application of percutaneous ethanol injection treatment.

Sonographically guided percutaneous ethanol injection (PEI) has been recently used with excellent results in the treatment of toxic and pretoxic thyroid adenoma. The aim of the present study was to assess the efficacy of PEI also in the treatment of "cold" thyroid nodules. Twenty patients, each with a single thyroid nodule, underwent PEI. In all cases the nodules were found to be cold by thyroid scintiscan. A total of 16.1 mL +/- 3.1 mL of ethanol was injected once a week. No adverse effects were observed during therapy. A striking nodular shrinkage was obtained in all cases, ranging from 72.8% to 97.6% (mean 84.5%, p < 0.001 vs pretreatment volume). These preliminary results suggest that PEI is an effective and safe therapy that may be useful in the treatment of thyroid nodules as an alternative to other therapies (surgery, L-thyroxine).

Thyroid carcinoma in childhood: Management and follow up of 11 cases

Eleven patients under 16 years of age, 5 males and 6 females were diagnosed with thyroid carcinoma in our hospital between 1974 and 1992. Median age at diagnosis was 9.5 years (range: 5.2-15.7 years). The presenting sign was a single thyroid nodule in 5, multiple thyroid nodules in 1, cervical adenopathy in 3, and thyroid nodules in conjunction with cervical adenopathy in 2 patients. Histological diagnosis was papillary carcinoma in 5 cases, follicular carcinoma in 2, mixed papillary-follicular carcinoma in 3, and anaplastic carcinoma in one. Only 4 patients had no extrathyroidal metastases at diagnosis. All but one subjects underwent total thyroidectomy, either one-stage or two-staged. If metastases were present, ablative radio-iodine therapy followed. Two patients died within a few months, one from complications of lung metastases, another from diffuse spread of anaplastic carcinoma. Two patients were lost to follow up; 7 patients have been followed for 9.0-18.0 years. Of these, one patient with initial lung metastases has had six recurrences which were successfully treated each time with radio-iodine although thyroglobulin levels remained elevated; another patient who had an initial subtotal thyroidectomy incurred a relapse 12 years later during pregnancy but is doing well now after more intensive surgery. We propose that children with differentiated thyroid carcinoma should undergo total thyroidectomy and selective lymph node extirpation by a skilled surgeon followed by whole body radio-iodine scan and ablative radio-iodine treatment if necessary. Plasma thyroglobulin can then be used as a tumour marker and suppressive levothyroxine does should be given.

RADIOISOTOPIC EVALUATION OF THE THYROID AND THE PARATHYROIDS

Since the inception of the discipline of nuclear medicine, thyroid evaluation and therapy with radioactive isotopes have remained an important and constant component of thyroidology. Parathyroid scintigraphy with 201Tl/99mTc subtraction has been a more recent and also very useful addition in the assessment of hyperparathyroidism, particularly at reoperation. The radioactive iodine uptake test gives important metabolic information on thyroid function in such diverse disease states as hyperthyroidism, hypothyroidism, the thyroiditides, and thyroid carcinoma. Thyroid scintigraphy is also a key contributor to the assessment of patients with hyperthyroidism or with single versus multiple thyroid nodules, those with a history of head and neck irradiation during childhood, and those requiring diagnostic follow-up studies with 131I after total thyroidectomy for differentiated thyroid carcinoma. Each of these topics is reviewed and expanded on in this article, with a diversity of illustrative scans provided to complement the discussion.