The controversy of the treatment of critically ill patients with thyroid hormone

There is currently a vast literature available on the changes in thyroid function tests that occur during non-thyroidal illness. The aetiology of these changes is, however, controversial, especially with respect to whether they play an adaptive role for the organism in order to cope with stress or whether they represent primary pathology of the pituitary-thyroid axis. This is particularly true for critically ill patients, in whom the most significant changes in thyroid function are observed. The changes include low levels of thyroxine and very low levels of tri-iodothyronine, which would, on the surface, appear to indicate hypothyroidism. Therapy with thyroid hormone, as either L-T4 or L-T3, has therefore been suggested because of these low values for thyroid hormones in the blood. It is, however, unclear whether treating these patients with thyroid hormone is beneficial or harmful. Multiple studies have addressed this issue with patients with cardiac disease, sepsis, pulmonary disease (e.g. acute respiratory distress syndrome) or severe infection, or with burn and trauma patients. In spite of a very large number of published studies, it is very difficult to form clear recommendations for treatment with thyroid hormone in the intensive care unit. Instead, we find the evidence far from compelling, and would advise withholding thyroid hormone therapy in the critical care setting in the absence of clear clinical or laboratory evidence for hypothyroidism.

Overexpression and overactivation of Akt in thyroid carcinoma

Enhanced activation of Akt occurs in Cowden's disease, an inherited syndrome of follicular thyroid, breast, colon, and skin tumors, via inactivation of its regulatory protein, PTEN. Whereas PTEN inactivation is uncommon in sporadic thyroid cancer, activation of growth factor pathways that signal through Akt is frequently identified. We hypothesized that Akt overactivation could be a common finding in sporadic thyroid cancer and might be important in thyroid cancer biology. We examined thyroid cancer cells lines and benign and malignant thyroid tissue for total Akt activation and isoform-specific Akt expression. In thyroid cancer cells, Akt 1, 2, and 3 proteins were expressed, total Akt was activated by insulin phosphatidylinositol 3'-kinase, and inhibition of phosphatidylinositol 3'-kinase reduced cell viability. In human thyroid tissue, increased levels of phosphorylated total Akt were identified in follicular but not papillary cancers compared with normal tissue. Levels of Akt 1 and 2 proteins and Akt 2 RNA were elevated only in the follicular cancers. In paired samples, Akt 1, 2, 3, and phospho-Akt levels were higher in five of six cancers, including three of three follicular cancers. These data suggest that Akt activation may play a role in the pathogenesis or progression of sporadic thyroid cancer.

Thyroid function in the intensive care unit setting

In sum, there is no convincing evidence yet published supporting the utility of T4 or T3 administration in patients with nonthyroidal illness. The authors recognize that evidence accrued in one disease state may not be applicable to others and that, although these studies are difficult to perform, further large scale prospective studies need to be performed. The issue of T3 treatment will not be resolved satisfactorily until more definitive data are available. Until that time, there may be rare circumstances when a clinician may think it best to treat an individual patient with T4 or T3. For the majority of patients, however, there will be little indication for the administration of thyroid hormones until the potential benefits can be shown to outweigh the risks.

Ultrasound-guided fine-needle aspiration and thyroid disease

BACKGROUND

Fine-needle aspiration represents a critical diagnostic test in determining proper management of thyroid disease and the use of ultrasound-guided fine-needle aspiration (USGFNA) has increased over the years.

METHODS

A retrospective chart review of patients undergoing USGFNA. Two hundred fifteen patients underwent 234 procedures with 362 nodules aspirated within a 2 (1/2)-year period.

RESULTS

The mean ages of women and men were 51.9 and 57.8, respectively. The average size of nodules was 2.1 cm. A difficult to assess gland or nodule was the most common indication for USGFNA (33%). The sensitivity was 88.2%, specificity was 80.0%, the PPV was 65.2%, the negative predictive value was 94.1%, and the accuracy was 82.5%. The cancer yield, inadequacy, and complication rates were 44%, 10.5%, and 8.5%, respectively.

CONCLUSIONS

USGFNA aspiration is a safe and effective diagnostic modality in the management of thyroid disease, especially for nodules that are difficult to palpate.

Cytotoxic activity of 2',2'-difluorodeoxycytidine (gemcitabine) in poorly differentiated thyroid carcinoma cells

Poorly differentiated and anaplastic thyroid cancers are aggressive and usually fatal neoplasms, despite aggressive treatment. We performed an in vitro study to assess the activity of gemcitabine (2',2' difluorodeoxycytidine), a new fluorinated nucleoside analogue, against three poorly differentiated human thyroid carcinoma cell lines (ARO, WRO, and NPA). Each cell line was exposed to increasing concentrations of gemcitabine (0.0003 to 3000 mumol/L) for 24, 48, and 72 hours. Maximal reduction in cell viability was seen after 72 hours of gemcitabine for all three cell lines as measured by 3-(4,5-dimethyl thiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) assay. NPA cells were more sensitive than the other two lines after 24 and 48 hours of exposure, but all cell lines were similarly sensitive at 72 hours. A cytotoxic effect was confirmed by DNA assay of adherent cells. IC50 concentrations for reduction in cell viability ranged from 0.731 and 0.986 mumol/L for each cell line after 72 hours of exposure. These concentrations are lower than serum levels in phase 1 clinical trials of gemcitabine for other malignancies. In summary, gemcitabine has activity against poorly differentiated thyroid cancer cell lines in vitro. In vivo studies using xenograft models are warranted to confirm these promising observations.

The role of radioactive iodine in salivary gland dysfunction

The use of radioactive iodine has become an important adjunct to the treatment of thyroid cancer. Many normal tissues--including salivary glands, gastrointestinal mucosa, gonads, and lactating breast tissue--have the ability to concentrate radioactive iodine under normal circumstances. Although the mechanism is just beginning to be elucidated, it is this ability that might contribute to the immediate and long-term complications associated with radioactive iodine treatment. In some patients, the salivary complications can be permanent and might compromise daily functioning. In this article, we examine the salivary gland complications associated with radioactive iodine therapy, and we suggest potential protective mechanisms to circumvent these problems.

Tall cell variant: an aggressive form of papillary thyroid carcinoma

Twenty-four cases of the tall cell variant (TCV), a subset of papillary thyroid carcinoma, were identified in a group of 624 patients with thyroid cancer. All pathology specimens were reviewed, and each patient's carcinoma was categorized according to characteristics on presentation, local recurrence, distant metastases, follow-up, and tumor-related mortality. The TCV group was compared with a historical control group (Mazzaferri and Jhiang: 1355 patients). The TCV group had a statistically higher percentage of stage 3 and 4 carcinoma, extrathyroidal invasion, and tumor size less than 1.5 cm than the control group. There was no statistical relationship between age greater than 50 years and stage in the TCV group. No relationship could be found between TCV histology and recurrence or mortality. These findings, combined with those of studies that link stage on presentation to poor outcomes, have led to our conclusion that TCV is an aggressive malignancy warranting appropriate treatment and close follow-up.

Prognostic importance of vascular invasion in papillary thyroid carcinoma

BACKGROUND

The prognostic importance of vascular invasion has not been extensively studied in patients with papillary thyroid cancer.

OBJECTIVE

To determine whether the presence of vascular invasion in papillary thyroid carcinoma, even within the thyroid gland, is associated with more aggressive disease at diagnosis and a higher incidence of tumor recurrence.

PATIENTS AND METHODS

We identified 410 patients who had been diagnosed with papillary thyroid cancer since 1986 who had a follow-up period of longer than 1 year (median follow-up, 5.5 years). Pathology reports were reviewed and patients were separated into 3 groups: no vascular invasion, intrathyroidal vascular invasion, and extrathyroidal vascular invasion.

MAIN OUTCOME MEASURES

Statistical comparison was performed by univariate and multivariate analysis.

RESULTS

Patients with intrathyroidal vascular invasion were more likely to have distant metastasis at the time of diagnosis (26.1% vs 2.2%, P = .001). Similarly, patients with extrathyroidal vascular invasion had a higher incidence of distant metastases at diagnosis (40% vs 4.4%, P = .02). Patients with tumors identified to have intrathyroidal vascular invasion were more likely to develop distant recurrence (20% vs 3%, P = .002).

CONCLUSIONS

These associations were found to be independent by multiple regression analysis. Patient age, sex, palpable or fixed lymph nodes, radiation exposure, and race did not differ between the patient group with and those without vascular invasion. Preliminary analysis of our data suggests that the presence of vascular invasion in papillary, thyroid carcinoma, even within the thyroid gland, is associated with more aggressive disease at diagnosis and with a higher incidence of tumor recurrence.

Quantitative reverse transcription-polymerase chain reaction of circulating thyroglobulin messenger ribonucleic acid for monitoring patients with thyroid carcinoma

Patients with thyroid cancer are monitored for disease recurrence by measurement of serum thyroglobulin (Tg) and iodine-131 (131I) scanning. To enhance sensitivity and to circumvent antibodies that interfere with Tg immunoassays, we have developed RT-PCR assays that detect circulating thyroid messenger RNA (mRNA) transcripts. We now report results using a sensitive quantitative Tg mRNA assay (Taqman; ABI, Foster City, CA) in comparison with immunoassay in patients previously treated for thyroid cancer. We evaluated 107 patients: 84 during T4 therapy, 14 after T4 withdrawal, and 9 at both time points. All patients had near-total thyroidectomy, and 92% received postoperative 131I. Serum TSH, Tg protein, and Tg mRNA were measured. Patients were grouped based on most recent 131I scan or pathologically confirmed disease as having no detectable thyroid tissue (n = 33), thyroid bed uptake (n = 37), cervical/regional adenopathy (n = 21), or distant metastases (n = 16). During T4 therapy, median (range) Tg mRNA values (pg Tg Eq/microg thyroid RNA) for the groups were 1.5 (0-26.8), 9.4 (0.5-90.0), 15.4 (0.2-92), and 12.4 (1.9-16.6), respectively. Using a value of 3 pg Tg Eq/microg thyroid RNA as cut-point, Tg mRNA was positive in 38% of patients with no uptake, 75% with thyroid bed uptake, 84% with cervical/regional disease, and 94% with distant metastases. The median Tg mRNA value for patients with no uptake was lower than the median values for patients with thyroid bed uptake (P = 0.009) or with detectable thyroid tissue at any site (P = 0.010). Patients with negative 131I whole body scans were also less likely to have detectable Tg mRNA levels than were patients with thyroid bed uptake (P < 0.001) or any detectable thyroid tissue at any location (P < 0.001). Similar differences between these groups were seen after T4 withdrawal and for the 23 patients with circulating anti-Tg antibodies, when analyzed separately. Eight of the nine patients studied with low and high TSH concentrations displayed greater amounts of circulating Tg mRNA after T4 withdrawal. In three patients followed prospectively, the amount Tg mRNA correlated with the presence and absence of cervical metastases. In conclusion, we have demonstrated that a quantitative Tg mRNA assay can identify thyroid cancer patients with recurrent or residual thyroid tissue with greater sensitivity and similar specificity to Tg immunoassay during T4 therapy. The assay was unaffected by anti-Tg antibodies, responded to TSH-stimulation, and was reduced after surgical removal of metastases. These data suggest that this quantitative Tg mRNA assay may be a sensitive marker of tumor recurrence or response to therapy, particularly in patients with anti-Tg antibodies.

Oxygen free radicals in interleukin-1beta-induced glycosaminoglycan production by retro-ocular fibroblasts from normal subjects and Graves' ophthalmopathy patients

Graves' ophthalmopathy (GO) is attributed to an autoimmune process that results in the accumulation in retro-ocular tissue of glycosaminoglycans (GAG) that are in turn responsible for the development of clinical signs and symptoms. Retro-ocular fibroblasts are thought to be the source of GAG production and deposition in GO. In the present study, we investigated interleukin (IL)-1beta-induced oxygen free radical production and the role of oxygen free radicals in IL-1beta-induced GAG production in retro-ocular fibroblasts from both normal subjects and patients with GO. Normal retro-ocular fibroblasts demonstrated no measurable oxygen free radicals whereas GO retro-ocular fibroblasts showed detectable signals by electron paramagnetic resonance (EPR) spectroscopy. IL-1beta increased the free radical production in both cells. Superoxide dismutase (SOD) activity in GO retroocular fibroblasts was higher than that in normal cells. IL-1beta dose- and time-dependently stimulated the SOD activity in both cells, with GO retro-ocular fibroblasts showing less responsiveness. IL-1beta dose-dependently increased [3H]glucosamine incorporation into GAG by both cells. An exogenous oxygen free radical-generating system failed to increase GAG. Scavenging oxygen free radicals by the use of SOD (100 U/mL) and catalase (300 U/mL) partially blocked the IL-1beta-induced GAG production in both cells. These results suggest that stress related oxygen free radicals are present in the retro-ocular tissue in GO and that oxygen free radicals are involved in GAG accumulation induced by cytokine IL-1beta.

Solitary cerebellar metastasis from papillary thyroid carcinoma: a case report

Papillary thyroid carcinoma is a common thyroid malignancy that generally has a good prognosis. However, this type of cancer may give rise to distant metastasis and may behave more aggressively in older patients. Here we report clinical, radiological, and pathological findings of a patient with papillary thyroid carcinoma who had a solitary cerebellar metastasis. The patient was known to have metastatic thyroid cancer to the lungs, but this had been stable and the cerebellar metastasis presented an unanticipated significant problem. The rapid detection of cerebellar metastatic disease is critical because neurosurgical removal of the solitary lesion should be considered as the treatment of choice. This case also serves to remind us of the importance of considering possible metastatic brain lesions and their acute life-threatening complications in contrast to the relatively prolonged course associated with metastases of thyroid carcinoma to other organs.

Immunodetection of manganese superoxide dismutase in cultured human retroocular fibroblasts using sera directed against the thyrotropin receptor

The identification of antigenic targets in the retroocular autoimmune response of Graves' ophthalmopathy is likely to increase our understanding of mechanisms underlying this disorder. While a number of putative autoantigens have been identified on the basis of molecular weight or cell of origin, a determination of the significance of these antigens is contingent upon an identification of the amino acid sequence. Our group has previously identified immunoreactive retroocular fibroblast (ROF) proteins recognized by thyrotropin receptor (hTSH-R) antisera (anti-p1), at molecular weights of 95, 71, 41, and 14-25 kDa. In the present study, proteins detected by anti-p1 and visualized by Ponceau staining were isolated and processed for microsequencing. Ponceau staining revealed dense bands at molecular weights of 14 and 23 kDa, and a weak band at 41 kDa. N-terminal sequencing was performed on the prominent band at approximately 23 kDa, showing it to be manganese superoxide dismutase (MnSOD), a mitochondrial enzyme responsible for protection against oxygen free radical-associated cellular damage. Sequence comparison of MnSOD to the hTSH-R peptide, p1, revealed a linear segment of amino acid homology. Preincubation of anti-p1 with p1 blocked immunodetection of the 23 kDa band corresponding to MnSOD, and immunoprecipitation of ROF protein using anti-pi yielded protein recognized by anti-MnSOD. Autoimmunity against human recombinant MnSOD was further assessed by ELISA. Patients with Graves' disease (n = 53) had significantly higher ELISA indices than normal control subjects (n = 29), while patients with Hashimoto's thyroiditis had intermediate values. These results document MnSOD autoantibodies in patients with Graves' disease and suggest that this may result from an immune cross-reactivity between MnSOD and the TSH-receptor.

Thyroid disease and osteoporosis

Prolonged elevation of thyroid hormones has been linked to osteoporosis and increased fracture risk. Whether thyroid hormone suppression also increases those risks remains controversial. Prophylaxis is often appropriate for patients who have had thyroid disorders, with assessment of bone mineral density and perhaps pharmacologic therapy for those with additional risk factors.

Soluble interleukin-2 receptor is a thyroid hormone-dependent early-response marker in the treatment of thyrotoxicosis

Thyrotoxic patients exhibit increased levels of immune activation molecules (soluble interleukin-2 receptor [sIL-2R], intercellular adhesion molecule-1 [ICAM-1], and endothelial-leukocyte adhesion molecule-1 [ELAM-1]) in serum, although the clinical significance of these measurements remains unclear. In a randomized 4-week study, we have recently shown that in the treatment of hyperthyroidism, the combination of cholestyramine and methimazole (MMI) resulted in faster lowering of serum thyroid-hormone levels than did MMI alone. Stored serial serum samples from patients participating in this randomized treatment trial were analyzed for sIL-2R, soluble ICAM-1 (sICAM-1), and soluble ELAM-1 (sELAM-1). The levels of all three molecules were elevated in patients with hyperthyroidism. Although the levels of sICAM-1 and sELAM-1 remained elevated through the 4-week follow-up period in both groups of patients, the sIL-2R levels (normal levels, 1.0 to 4.2 ng/ml) decreased significantly in the 10 patients who received cholestyramine in addition to MMI (week 0, 14.2 +/- 1.5 ng/ml; week 2, 10.8 +/- 1.2 ng/ml; week 4, 8.9 +/- 1.5 ng/ml). In eight patients who received MMI alone, sIL-2R decreased less rapidly (week 0, 12.3 +/- 1.4 ng/ml; week 2, 12.3 +/- 1.3 ng/ml; week 4, 10.9 +/- 1.3 ng/ml). sICAM-1 and sELAM-1 were elevated at baseline but did not decrease during therapy. In the former group, free thyroxine and free triiodothyronine decreased faster. These data show that levels of sIL-2R in serum, but not those of sICAM-1 and sELAM-1, may be of clinical use in the early follow-up evaluation of medically treated patients.

Hodgkin's disease treated with neck radiation is associated with increased antibody-dependent cellular cytotoxicity against human extraocular muscle cells

Patients with Hodgkin's disease have higher a prevalence of thyroid function abnormalities and, perhaps, orbitopathy than the general population, but the pathophysiology of this association and its relationship to Hodgkin's disease treatment remain unclear. We analyzed the frequency of thyroid function abnormalities, autoantibodies against thyroid antigens, and autoimmunity against extraocular muscle cell antigens by Western blot analyses and antibody-dependent cellular cytotoxicity (ADCC) assays in patients with Hodgkin's disease (n = 20) and controls (n = 10). Hodgkin's disease patients were subdivided into those treated with thyroidal external beam radiation therapy (XRT, n = 15) or chemotherapy (MOPP/ABVD, n = 5). The ADCC assay against extraocular muscle cells was increased in patients with Hodgkin's disease (5.5% vs. <1.0%, p = .026) when compared with controls. In addition, Hodgkin's disease patients treated with XRT (with or without chemotherapy) had significantly higher ADCC tests than controls (9.7% vs. <1.0%, p = .010), In contrast, ADCC assays were not different between Hodgkin's disease patients treated with chemotherapy alone and controls (<1.0% vs. <1.0%, p = .53). Hodgkin's patients treated with XRT had higher ADCC assays than those treated with chemotherapy alone (p = .087), although this difference did not achieve statistical significance. Serum measurements of antithyroid peroxidase (TPO) antibodies, antithyroglobulin (Tg) antibodies, thyroid binding inhibitory immunoglobulins (TBII), and thyroid stimulating immunoglobulin (TSI) were similar in all groups. Antibodies against the 64 kDa orbital antigen were detected in 1 patient and 1 control subject. Excluding patients already treated with L-thyroxine for hypothyroidism (n = 5), free T3, but not free T4, was lower in the Hodgkin's disease group than in controls (2.2 pg/mL vs. 2.7 pg/mL, p = .008). Thyrotropin (TSH) concentrations were not statistically different between these groups. In summary, these data show: (1) ADCC against human orbital muscle cells is increased in patients with Hodgkin's disease compared with controls: (2) these differences were noted among Hodgkin's disease patients treated with thyroidal XRT, with or without chemotherapy, and not among those patients treated with chemotherapy alone; and (3) no statistically significant differences in the frequency of thyroid autoantibodies were found. These data suggest that patients with Hodgkin's disease display altered antibody-dependent immune function toward extraocular muscle cells that may possibly be related to by XRT. Larger, prospective studies assessing thyroid and orbital-related immunologic abnormalities in Hodgkin's disease are warranted.

Fine needle aspiration of thyroid nodules. Determinants of insufficiency rate and malignancy yield at thyroidectomy

OBJECTIVE

To evaluate patient- and practice-specific determinants of the thyroid nodule fine needle aspiration (FNA) insufficiency rate and malignancy yield at a tertiary-care teaching hospital.

STUDY DESIGN

All FNAs of thyroid nodules performed from August 1990 to October 1993 at the Walter Reed Army Medical Center Endocrinology Clinic were reviewed and the results analyzed for correlation with surgical outcome, scintiscanning result and operator experience. Provider-specific factors influencing the FNA insufficiency rate, surgical referral pattern and malignancy yield were evaluated.

RESULTS

A total of 504 aspirations in 422 patients with thyroid nodules were included in the analysis. The sensitivity of FNA for detecting malignancy was 80%, specificity was 73.2%, and accuracy was 75.2%. A significant negative correlation was found between recent aspirator experience and the insufficiency rate. Repeat aspiration of nodules previously yielding benign cytology increased the malignancy yield. Surgical excision of nodules with insufficient aspirations gave a low malignancy yield, and aspiration of nodules that were "hot" on scintiscanning rarely yielded false positive FNA results.

CONCLUSION

Specific limitations of thyroid nodule FNA include a large number of aspirates containing insufficient cytologic material and a variable malignancy yield. Specific recommendations based on the findings in this report are: the establishment of uniform criteria for judging specimen adequacy, the performance of repeat aspiration on thyroid nodules with previously benign aspirates, the abandonment of scintiscanning in the routine management of thyroid nodules and a conservative approach to clinically indolent nodules repeatedly found to have scant cellularity on FNA. Based on these findings, an algorithm for the diagnostic evaluation of a solid thyroid nodule can be constructed.

Immunoglobulins from Graves' disease patients stimulate phospholipase A2 and C systems in FRTL-5 and human thyroid cells

We have studied the effects of immunoglobulin G from Graves' disease patients on phospholipase A2 (PLA2) and C(PLC) systems in FRTL-5 and human thyroid cells. Immunoglobulin G (IgG) from Graves' disease patients stimulated arachidonic acid (AA) release in a time- and dose-dependent manner. In FRTL-5 thyroid cells, removal of external calcium had no significant effect on the IgG (20 micrograms/ml)-induced AA release in FRTL-5 thyroid cells. U-73122 (3 mumol/l), a PLC inhibitor, and quinacrine (100 mumol/l) but not U-26384 (5 mumol/l), PLA2 inhibitors, blocked the IgG-induced (20 micrograms/ml) AA release in FRTL-5 thyroid cells. Immunoglobulin G (100 micrograms/ml) also stimulated accumulation of inositol-1,4,5-triphosphate (IP3) in a time- and dose-dependent (20-300 micrograms/ml) manner in FRTL-5 cells. Immunoglobulin G from Graves' disease patients induced a significant increase of IP3 production (p = 0.01) compared to IgG from normal subjects. Removal of external calcium had no significant effect on the IgG-induced IP3 production. The PLC inhibitor U-73122 completely blocked IgG-induced IP3 production from FRTL-5 thyroid cells. Also, in human thyroid cells, IgG from Graves' disease patients induced a significant increase of AA release (p = 0.001) and IP3 production (p = 0.004) compared to the IgG from normal subjects. These data indicate that IgG from Graves' disease patients induced PLA2 activity that was PLC dependent, a pattern referred to as sequential activation. Our studies suggest that IgG from Graves' disease patients activates PLA2 and PLC systems in FRTL-5 and human thyroid cells. These signal transduction pathways could be involved in the pathogenesis of Graves' disease and future studies are warranted to investigate this area.

Unusual types of thyroid neoplasms

This article discusses several unusual forms of primary thyroid neoplasms. The TCV of PTC and insular thyroid carcinoma appears to have a more aggressive clinical behavior than DTC in most patient groups and may respond to thyroid hormone suppression and radioiodine. Anaplastic thyroid carcinoma, which may develop from differentiated thyroid tumors, has a poor prognosis which may be altered by surgery and radiation therapy but not typically by radioiodine and thyroid hormone suppression. Primary squamous cell carcinoma of the thyroid is an unusual entity that may be associated with a clinical syndrome that includes leukocytosis, fever, and hypercalcemia. Primary thyroid lymphoma is frequently associated with Hashimoto's thyroiditis and should be considered especially in older patients with rapidly enlarging thyroid masses. Although there are no studies assessing this issue, it seems reasonable that patients who have undergone thyroidectomy for neoplasms of thyroid cells that are poorly differentiated and do not concentrate radioiodine (e.g., squamous cell, anaplastic) should receive sufficient thyroid hormone suppression, if tolerated, to reduce TSH (third-generation assay) to approximately 0.1 to 0.3 mu U/mL, because TSH may be a growth factor. If, however, the tumor concentrates or responds to radioiodine, suggesting more differentiated cells (e.g., TCV, insular carcinoma), the target TSH level (third-generation assay) should range from 0.01 to 0.1 mu U/mL, as tolerated. Patients with primary thyroid neoplasms arising from cells other than thyrocytes (e.g., lymphoma) can be maintained at a TSH level of 0.5 to 1.5 mu U/mL. Our conclusions and analyses are often based upon small, retrospective, poorly controlled reports, and further studies are required to allow a better understanding of the evaluation and treatment of these neoplasms.

Current trends in the management of well differentiated papillary thyroid carcinoma

Clinical members of the American Thyroid Association were surveyed in regard to their diagnostic assessment, treatment, and long term assessment of differentiated papillary thyroid carcinoma. For a 39-yr-old female with a 2-cm solitary nodule and no history of radiation (index patient), respondents were asked to provide their preferences for diagnostic evaluation, treatment assuming a papillary carcinoma was focal, and follow-up. Of 408 surveys mailed, 233 (57.1%) were analyzed. Diagnostic studies included thyroid scan (56%), fine needle aspiration (96%), total serum T4 (49%), and third generation TSH (56%). Treatment included surgery (99%), with 86% preferring near-total/total thyroidectomy. After surgery, 61% recommended 131I ablation; long term therapy using L-T4 alone was recommended by 97%, with most preferring suppression to a target TSH level of less than 0.01 microIU/mL (22%), 0.01-0.05 (38%), or 0.06-0.50 (32%). For variations from the index patient, respondents' treatment were not different for a history of radiation, age of either 16 or 60 yr, nodule size of 1.5 cm, male sex, the presence of less than 1-cm multiple foci in the contralateral lobe, or capsular invasion of the nodule. Treatment and follow-up did change if there was blood vessel invasion or distant metastasis. In summary, our survey indicated consensus on diagnostic assessment of the index patient by fine needle aspiration and management by surgery and 131I therapy. However, management varied widely for the ablative dose of 131I, the target TSH level after ablation, and the frequency and type of follow up.

The influence of triiodothyronine, thyroxine, thyrotropin, and methimazole on thyroid cell MHC class II antigen expression

We have studied the influence of triiodothyronine (T3), thyroxine (T4), thyrotropin (TSH), and methimazole (MMI) on the expression of major histocompatibility (MHC) Class II antigen expression in human thyroid cells. T3, T4, TSH, and MMI in various combinations were added together with interferon-gamma (IFN-gamma) to human thyrocytes or to cultured FRTL-5 cells. Neither T3 nor T4, alone, caused inhibition of the IFN-gamma stimulation of thyrocyte HLA-DR expression. Moreover, the combination of both drugs at various concentrations did not inhibit this expression except only in low ranges (T3 at 0.3 nmol/liter and T4 at 12.9 nmol/liter). MMI only at a concentration of 3.0 mmol/liter caused significant inhibition of IFN-gamma-induced HLA-DR expression. However, the addition of T3 (range, 0.3-9.2 nmol/liter) or T4 (12.9-129.0 nmol/liter) prevented the MMI-induced inhibition. This phenomenon may be explained by the action of MMI on inhibiting the synthesis of T3 and T4. At a concentration of 100 microU/ml, TSH enhanced IFN-gamma-induced HLA-DR expression. It is possible that TSH induced the expression of large numbers of IFN-gamma receptors, thereby enhancing the production of HLA-DR in response to IFN-gamma. Our studies suggest that MMI does not alter thyrocyte HLA-DR expression in vitro, especially when combined with T3 or T4; however, MMI may still induce or perpetuate immune effects in vivo secondary to its influence on thyroid hormone production or thyroid antigen presentation.