Age modifies the response to recombinant human thyrotropin

BACKGROUND

A standardized protocol is used to administer recombinant human thyrotropin (rhTSH) in preparation for diagnostic studies and treatment in patients with thyroid cancer. The expectation is that serum TSH concentrations will peak on the day after the second injection and will be sufficiently elevated to stimulate uptake of radioiodine. We wished to test the hypothesis that TSH concentrations achieved after rhTSH injection are influenced by age.

METHODS

Patients with thyroid cancer undergoing diagnostic radioiodine scanning were identified by chart review. Serum TSH concentrations were documented 24 and 72 hours after two rhTSH injections (days 3 and 5, respectively). Responses were subdivided into four ascending patient age groups: <35, 35-49, 50-64, and >64 years. TSH concentrations after rhTSH administration were documented according to patient age.

RESULTS

There was a significant correlation between the serum TSH concentrations at both days 3 and 5 and patient age (p < 0.0001). None of the other factors examined (gender, menopausal status, weight, body mass index, baseline TSH, serum creatinine, and estimated glomerular filtration rate) were significant in multivariate analyses. The mean TSH concentration on day 3 increased significantly when patients were divided into the aforementioned groups of ascending age (96, 107, 142, and 196 mIU/L, p < 0.0001). Day 5 concentrations increased in a similar manner.

CONCLUSIONS

Both days 3 and 5 TSH concentrations were higher in older individuals after rhTSH administration. This finding did not appear to be related to body weight, body mass index, or glomerular filtration rate in a simple manner. The TSH concentration achieved may be a result of complex interactions between distribution within fat and muscle body compartments, hepatic function, and renal function. Prospective studies could examine whether the magnitude of the TSH elevation after rhTSH administration affects diagnostic or therapeutic efficacy.

Graves' disease and thymic hyperplasia: the relationship of thymic volume to thyroid function

BACKGROUND

Thymic hyperplasia is associated with Graves' disease, particularly in young patients. The degree of thymic transformation is minimal in most but not all patients. In the latter group radiological measurements of thyroid size and their change with treatment have rarely been reported. We present two patients with Graves' disease and relatively rapid resolution of thymic enlargement after successful treatment of their hyperthyroidism.

SUMMARY

Three patients with thyrotoxicosis secondary to Graves' disease and marked thymic enlargement were seen at our institution during a 2-year period. On computed tomography (CT) studies their volumes were 67, 81, and 54 cm(3). Thymic hyperplasia in the setting of Graves' disease was the diagnosis of exclusion. Two of the patients returned for follow-up after successful treatment of thyrotoxicosis as requested. On repeat CT their thymic volumes had decreased by 72% and 78%, respectively. Two types of histological modifications of the thymus have been described in association with Graves' disease, namely, thymic parenchyma hyperplasia and medullary lymphoid hyperplasia. The mechanisms underlying thymic transformation in patients with Graves' hyperthyroidism are not completely elucidated, but autoimmune processes underlying Graves' disease are presumed to play a role. The clinical course of our patients is consistent with earlier literature, indicating that thymic enlargement may occur in conjunction with Graves' hyperthyroidism, and that it usually resolves as hyperthyroidism is treated, but there is little quantitative pre- and posttreatment of hyperthyroidism data.

CONCLUSION

Although every patient must be individually considered, it appears that thymic hyperplasia can be diagnosed in most Graves' hyperthyroid patients by considering the clinical context and appropriate radiologic studies such as CT. Raising awareness of the association of thymic hyperplasia in patients with Graves' hyperthyroidism and its resolution with the reversibility of the hyperthyroid state should prevent unnecessary thymic evaluation and surgery with its attendant risks.

Age and the thyrotropin response to hypothyroxinemia

CONTEXT

Some studies suggest altered pituitary functioning and TSH production with aging.

OBJECTIVE

Our objective was to test the hypothesis that less TSH production occurs despite comparable hypothyroxinemia with advancing age.

DESIGN

We retrospectively studied adult outpatients of all ages with confirmed hypothyroidism and documented their TSH and free T4 concentrations.

PARTICIPANTS

Two populations of 112 patients were subdivided into four age groups: 1) patients newly diagnosed with primary hypothyroidism and 2) thyroid cancer patients undergoing l-T4 withdrawal in preparation for diagnostic or therapeutic radioiodine.

MAIN OUTCOME MEASURE

The relationship between paired free T-4 and TSH concentrations and patient age was studied.

RESULTS

With spontaneous hypothyroidism, the mean TSH concentration decreased nonsignificantly in each ascending age group with comparable free T4 (FT4) concentrations (<35 yr, 69 mIU/liter; 35-49 yr, 49 mIU/liter; 50-64 yr, 43 mIU/liter; >64 yr, 29 mIU/liter). With iatrogenic hypothyroidism, the mean TSH concentration decreased significantly in each ascending age group (<35 yr, 156 mIU/liter; 35-49 yr, 115 mIU/liter; 50-64 yr, 74 mIU/liter; >64 yr, 46 mIU/liter; P<0.001) despite similar FT4 concentrations. The relationship between the log-transformed TSH and FT4 was significantly and inversely affected by age in multivariate analyses in both spontaneous hypothyroidism (P=0.0005) and in iatrogenic hypothyroidism (P<0.0001).

CONCLUSIONS

Age modifies the pituitary set point or response to comparably reduced free T4 concentrations, resulting in lesser serum TSH elevation in older individuals. This phenomenon occurs with both spontaneous and iatrogenic hypothyroidism. This may be an adaptive response in normal aging or a pathological alteration of pituitary function with age.

Salivary gland malignancy and radioiodine therapy for thyroid cancer

BACKGROUND

The risk of second primary malignancies in patients with well-differentiated thyroid cancer is of special interest because of the common use of radioactive iodine (RAI) ablation and/or treatment of these patients and the theoretical risk of subsequent nonthyroid malignancies associated with the radiation exposure. This brief report focuses specifically on the occurrence of second primary malignancies of the salivary glands. RAI residency within salivary tissues is known to have both acute and chronic consequences on salivary function, but secondary neoplasia is quite unusual.

SUMMARY

We present a very rare case of a patient with papillary thyroid cancer treated with 600 mCi of RAI, who subsequently developed salivary gland cancer.

CONCLUSIONS

We recommend salivary gland protection to diminish potential side effects after the exposure to radioiodine. On the basis of our experience we suggest administration of sialogogues (such as lemon juice) continuously, every 30-60 minutes for 24 hours, after RAI administration.

Thyroid nodule and thyroid cancer management pre- and post-cardiac transplantation

Thyroid nodules are common in the adult population. Widespread use of sensitive imaging studies often leads to their incidental discovery. Recent guidelines recommend thyroid-stimulating hormone determination and ultrasonography during initial nodule evaluation. Fine-needle aspiration is often performed to detect malignancy. However, the management of thyroid nodules in cardiac transplantation patients has not been directly addressed by recent guidelines. Confounding medications such as amiodarone and anti-coagulants present a management dilemma. The timing of fine-needle aspiration is crucial because (1) malignancy diagnosed pre-operatively usually precludes organ transplantation, and (2) patients undergoing solid-organ transplantation are at increased risk of developing de novo malignancies, including thyroid. With the rising incidence of thyroid cancer, donor-related malignancy will likely become a more prominent issue. This review addresses thyroid nodule management in the cardiac transplant population and provides recommendations for organ donation and transplantation in donors and recipients with thyroid cancer.

Metastases of well-differentiated thyroid cancer to the gastrointestinal system

BACKGROUND

The incidence of distant metastases at the time of initial presentation of well-differentiated thyroid cancer is approximately 4%. During the course of treatment and follow-up, the prevalence of distant metastases ranges from 2% in low-risk patients up to 33% in high-risk patients. When present, distant metastases occur primarily in the lungs and, to a lesser extent, in bones. Of all sites for distant metastasis, gastrointestinal metastases of thyroid cancer are very uncommon and account for 0.5-1% of all distant metastases.

SUMMARY

Indications of metastases to the gastrointestinal system can be overlooked with traditional total body radioisotope scans that image the abdomen, including both diagnostic and posttherapy scans, because of the confounding presence of physiologic enteric radioactivity. When suspected in high-risk patients, other imaging procedures such as computed tomography, magnetic resonance imaging, and PET-computed tomography should be considered. This communication will review thyroid cancer metastases to the gastrointestinal system in regard to occurrence rate, diagnosis, and treatment.

CONCLUSIONS

Because of the extreme rarity of patients with metastases of thyroid cancer to the gastrointestinal tract, long-term follow-up data as well as information on prognosis are very limited. Aggressive management may provide symptomatic relief or palliation, but cure is unlikely once widespread metastases supervene. Attempts at complete or near-complete surgical resection of the metastases invading the digestive tract, followed by 131-I treatment, offer the best opportunity for improvement but will only rarely result in cure in selected patients.

Acute bacterial suppurative thyroiditis: a clinical review and expert opinion

BACKGROUND

Acute suppurative thyroiditis (AST) resulting from a bacterial infection is an infrequent but potentially life-threatening endocrine emergency. Traditional management of this disease has been surgery in conjunction with targeted antibiotic therapy. Recent nonrandomized reports of small series have demonstrated good outcomes using less invasive approaches. No randomized clinical trials have been performed. Here, we provide a review of the literature and an approach to this problem based on expert opinion.

METHODS

The literature was reviewed utilizing PubMed, and a representative case of AST was presented to a panel of experts. Endocrinology, surgery, and infectious disease experts responded to a series of questions regarding diagnosis, management, prognosis, and harm.

RESULTS

Combining a broad spectrum of clinical expertise and the published literature, the authors suggest a clinical algorithm as a guide to management, addressing both diagnosis and acute and long-term management.

CONCLUSIONS

Published studies indicate a trend toward less invasive management during active inflammation and infection and regarding definite therapy. Remaining questions are presented to foster an evidence-based approach to this disease. Ideally, future randomized, controlled trials will provide data to improve the therapy and outcome of AST.

Utility of the radioiodine whole-body retention at 48 hours for modifying empiric activity of 131-iodine for the treatment of metastatic well-differentiated thyroid carcinoma

BACKGROUND

Dosimetry has been used to help identify when empiric dosages of 131-I treatment for suspected metastatic well-differentiated thyroid carcinoma (WDTC) may be increased or should be decreased, but dosimetry is complex, and easier approaches would be useful. The three objectives of this study were to assess the utility of the percent whole-body retention of 131-I at 48 hours (%WBR(48hr)) in identifying patients with WDTC in whom the therapeutic empiric prescribed activity of 131-I might be increased/decreased, to evaluate the thresholds proposed by Sisson et al. in 2003 for increasing or decreasing activity, and to determine the relationship between %WBR(48hr) and maximum tolerated activity (MTA).

METHOD

A retrospective review was conducted of patients who had WDTC, total thyroidectomy, suspected metastatic disease, thyroid hormone withdrawal, and 131-I dosimetry. The %WBR(48hr) was determined based on the Benua-Leeper dosimetry protocol, and the four thresholds and recommendations of Sisson et al., 2003 for the use of %WBR(48hr) were evaluated relative to an empiric activity (EA) of 7.4 GBq of 131-I. A biexponential equation was determined from the %WBR(48hr) data.

RESULTS

Of 142 patients, 47 patients had a %WBR(48hr) of <9%, and all could have received more than the EA of 7.4 GBq with an average of 21.0 GBq (incremental range of 6.8-23.2 GBq). Ten patients had a %WBR(48hr) < or = 5%, and all could have had their EA of 7.4 GBq safely increased by at least 250%. Conversely, if the %WBR(48hr) was >24.8%, then 7 of 14 of these patients would have exceeded the MTA by 0.37-3.18 GBq with an EA of 7.4 GBq. Finally, for patients with a %WBR(48hr) > 40%, five of six patients would have exceeded the MTA by 0.85-3.18 GBq. A biexponential regression equation is presented.

CONCLUSION

We conclude that, with respect to the treatment of metastatic epithelial cell thyroid cancer, the %WBR(48hr) of 131-I helps identify those patients in whom the empiric therapeutic prescribed activity of 131-I may be increased or should be decreased so as not to exceed the MTA and that Sisson et al.'s thresholds published in 2003 are applicable. We favor a biexponential regression model using the %WBR(48hr) and a lower limit threshold as a potentially useful method for determining how much an empiric therapeutic prescribed activity of 131-I can be increased or decreased.

Two cases of statin-induced myopathy caused by induced hypothyroidism

OBJECTIVE

To present information regarding the potential danger of performing levothyroxine withdrawal radioiodine scans and treatment in patients with thyroid cancer who are concurrently taking lipid-lowering agents.

METHODS

We review the clinical history, serial laboratory data, and radiologic findings in 2 patients with multifocal papillary carcinoma of the thyroid.

RESULTS

Both study patients had substantial elevations of muscle enzymes or myopathies (or both) when they were withdrawn from levothyroxine therapy, during treatment with lipid-lowering agents, in preparation for radioiodine scanning and treatment.

CONCLUSION

Extreme caution should be exercised when levothyroxine therapy is withdrawn from patients taking lipid-lowering agents. Such patients should be monitored very closely or, when appropriate, recombinant human thyroid-stimulating hormone injections should be used rather than levothyroxine withdrawal in this setting.

Retrobulbar 99mTc-diethylenetriamine-pentaacetic-acid uptake may predict the effectiveness of immunosuppressive therapy in Graves' ophthalmopathy

BACKGROUND

In Graves' ophthalmopathy (GO), only patients with immunologically active disease respond to immunosuppressive therapy. Previous studies and theoretical considerations suggest that elevated orbital (99m)Tc-diethylenetriamine-pentaacetic-acid (DTPA) single photon emission computed tomography (SPECT) reflects inflammatory disease activity. We studied whether corticosteroid treatment causes a substantial decrease in DTPA uptake in GO, a result consistent with successful immunosuppressive treatment of GO and referred to as a favorable treatment outcome.

METHODS

One hundred fourteen orbits in 57 patients with active GO (CAS >or= 4) were entered into the study. All patients received corticosteroid treatment. Orbital DTPA uptakes were numerically quantified for the entire orbit as well as the anterior and posterior segments separately. DTPA SPECT was performed before, and 2 to 9 months after the initiation of immunosuppressive treatment. The normal range for DTPA uptake was established in 34 orbits of 17 patients who were being worked up for Raynaud's phenomenon and had no thyroid disease.

RESULTS

The mean DTPA uptake of the 114 orbits of GO patients was higher prior to corticosteroid therapy than after this treatment (11.03 +/- 4.26 MBq/cm(3) and 9.84 +/- 3.51 MBq/cm(3), respectively, p < 0.001) but a substantial decline in DTPA uptake was seen in only 39.5% of GO patients. The positive predictive value of an initial DTPA >12.28 MBq/cm(3) for a substantial decline in DTPA uptake (favorable treatment outcome) was 76%, while a negative predictive value of a pretreatment DTPA <or=12.28 MBq/cm(3) was 78%.

CONCLUSIONS

Corticosteriod treatment is associated with a decline in DTPA uptake in a fraction of GO patients. GO patients with a DTPA uptake above 12.28 MBq/cm(3) are more likely to have a favorable response to corticosteroid therapy while patients with lower values are less likely to have this potentially favorable response. An elevated DTPA uptake may identify patients who are most likely to benefit from immunosuppressive treatment.

The magnitude of increased levothyroxine requirements in hypothyroid pregnant women depends upon the etiology of the hypothyroidism

BACKGROUND

In the United States, many women with hypothyroidism are on thyroid hormone replacement during pregnancy. The optimal management strategy for thyroid hormone dosing in hypothyroid women during pregnancy is controversial. We hypothesized that dosage requirements during pregnancy might differ depending upon the nature of the underlying hypothyroidism.

METHODS

We conducted a retrospective review of 45 pregnancies from 38 women whose hypothyroidism was managed during pregnancy. Thyroid function tests were obtained when pregnancy was confirmed, then every 4-8 weeks. The thyrotropin (TSH) goal was 0.4-4.1 microU/mL (SI unit conversion: multiply TSH by 1.0 for mIU/L).

RESULTS

On average, the entire group required a cumulative increase from baseline in levothyroxine (LT(4)) dosage of 13% in the first trimester, 26% in the second trimester, and 26% in the third trimester (p < 0.001, p < 0.001, p < 0.001, respectively). Average baseline LT(4) dose for patients with primary hypothyroidism was 92.5 +/- 32.0 microg daily. These patients required small cumulative dose increases of 11%, 16%, and 16% from baseline in each trimester, respectively (p values = 0.125, 0.016, 0.016). Average baseline LT(4) dose for patients with hypothyroidism resulting from treated Graves' disease or goiter was 140.4 +/- 62.4 microg daily. These patients required the largest cumulative increases in LT(4) dosage (first trimester, 27%; second trimester, 51%; third trimester, 45%; p = 0.063, 0.063, 0.063, respectively). Average baseline LT(4) dose for patients with thyroid cancer was 153.2 +/- 30.3 microg. The cumulative LT(4) dose increases for patients with thyroid cancer were 9%, 21%, and 26% in each trimester, respectively (p = 0.03, p < 0.001, p < 0.001).

CONCLUSIONS

The etiology of hypothyroidism plays a pivotal role in determining the timing and magnitude of thyroid hormone adjustments during pregnancy. Patients require vigilant monitoring of thyroid function upon confirmation of conception and anticipatory adjustments to LT(4) dosing based on the etiology of their hypothyroidism.

Hyperthyroid heart disease

The heart is an organ sensitive to the action of thyroid hormone, and measurable changes in cardiac performance are detected with small variations in thyroid hormone serum concentrations. Most patients with hyperthyroidism experience cardiovascular manifestations, and the most serious complications of hyperthyroidism occur as a result of cardiac involvement. Recent studies provide important insights into the molecular pathways that mediate the action of thyroid hormone on the heart and allow a better understanding of the mechanisms that underlie the hemodynamic and clinical manifestations of hyperthyroidism. Several cardiovascular conditions and drugs can interfere with thyroid hormone levels and may pose a difficulty in interpretation of laboratory data in patients with suspected thyroid heart disease. The focus of this report is a review of the current knowledge of thyroid hormone action on the heart and the clinical and hemodynamic laboratory findings as well as therapeutic management of patients with hyperthyroid heart disease.

Thyrotoxicosis-induced ventricular arrhythmias

BACKGROUND

Cardiac arrhythmias associated with thyrotoxicosis tend to be supraventricular in nature with atrial fibrillation being the most common. Ventricular arrhythmias are rarely associated with thyrotoxicosis and are considered to be secondary to intrinsic cardiac disease.

SUMMARY

We present three patients with thyrotoxicosis and stable coronary disease in whom the primary cardiac rhythm disturbance was ventricular tachycardia. In all of these patients, the ventricular arrhythmias terminated with achievement of a euthyroid state. We hypothesize that the thyrotoxic state contributed to the etiology of, or lowered the threshold for the ventricular arrhythmias.

CONCLUSION

Prompt attention to the management of thyrotoxicosis in patients with a history of significant heart disease is warranted in order to avoid potentially fatal arrhythmias.

Anaplastic thyroid cancer

Anaplastic thyroid cancer is an uncommon, typically lethal malignancy of older adults with no effective systemic therapy. The mean survival time is usually less than 6 months from the time of diagnosis and, unfortunately, this outcome is not fundamentally altered by available treatments. Histologic tissue confirmation is recommended if the diagnosis is not absolutely certain to exclude tumors with better prognosis or that require different treatment. Patency of the airway should be kept in mind throughout the patient's course and individuals with impending airway obstruction, in the absence of imminent death from other sites of disease, should be considered for a tracheostomy to secure the airway. Enrollment in meaningful clinical trials should be given the highest priority at all decision points.

Myxedema coma

Untreated or unrecognized hypothyroidism may progress to severe decompensated hypothyroidism or myxedema coma. Relatively few cases are reported in the literature since the first case was apparently reported from the St. Thomas Hospital in London in 1879. The paucity of cases may be due to either underreporting or improvement in the diagnosis and treatment of uncomplicated hypothyroidism. However, despite the ready availability of sensitive thyrotropin assays, the recognition and treatment of myxedema coma remains a challenge. Although thyroid hormone treatment is highly effective when combined with ventilatory and hemodynamic support in the intensive care unit setting, controversies abound on the optimal and most effective choice of thyroid hormone preparation: thyroxine and triiodothyronine and in what amount. Accumulated evidence now shows that proper use of either thyroxine alone or in combination with triiodothyronine may be effective therapy.

Autoimmune thyroid disease and chronic urticaria

We report six cases of autoimmune thyroid disease associated with chronic urticaria and briefly review the literature, including the histopathological nature of such lesions, and their aetiology and pathogenesis. In view of the prevalence of thyroid disease in patients with chronic urticaria, screening measurements of thyrotropin and anti-thyroperoxidase antibodies are recommended, although negative antibodies do not exclude a relationship between urticaria and thyroid autoimmunity. After failure of conventional therapy for urticaria, patients who are apparently clinically euthyroid may be considered for a trial with levothyroxine. Improvement of urticaria was seen with levothyroxine treatment in three of four patients with only marginal abnormalities in thyroid function.

Thyroid cancer molecular signaling pathways and use of targeted therapy

Several agents are currently being tested that target thyroid molecular signaling and cancer cell biology. The pathways involved include but are not limited to the Ras pathway, vascular endothelial growth factor and epidermal growth factor receptors and antibodies, angiogenesis inhibitors, tyrosine kinase inhibitors, heat shock protein inhibitors, demethylating agents, histone deacetylase inhibitors, and gene therapy. Each of these targeted approaches holds promise for our future ability to treat patients with thyroid cancer unresponsive to traditional therapy.

Hypothyroidism

Hypothyroidism is one of the most common disorders encountered in an endocrine office practice. This article reviews the epidemiology, etiology, clinical presentation, diagnosis, and treatment of hypothyroidism. We emphasize some of the more recent issues, such as combination thyroid hormone therapy, management of hypothyroidism during pregnancy, and the management of subclinical hypothyroidism.

Dermatologic aspects of thyroid disease

Thyroid disorders commonly have dermatologic manifestations. The purpose of the present chapter is to review and emphasize potential clinical dermatologic findings that can occur with Graves' disease, hypothyroidism and thyroid cancer. In autoimmune diseases such as Graves' disease and Hashimoto's thyroiditis the skin manifestations may be related to either thyroid hormone levels themselves or to the associated T and/or B cell abnormalities. Thyroid cancer may be associated with various syndromes that could have significant skin manifestations.

Overt and ???Subclinical??? Hypothyroidism in Women

Thyroid disease in general, and hypothyroidism in particular, are very common in women. In the USA, the most common cause of primary thyroid deficiency is on an autoimmune basis due to lymphocytic (Hashimoto) thyroiditis. Because there are thyroid hormone receptors in virtually every tissue of the body, the manifestations of hypothyroidism are varied, but problems with abnormal menses, conception, fertility, and pregnancy can be especially troubling in young women. The single most important diagnostic test is measurement of serum thyrotropin (TSH). The overwhelming majority of patients with hypothyroidism are treated with a single daily dose of synthetic levothyroxine with the goal of therapy being restoration of a normal metabolic state with return of the TSH level down to the range of 0.5 to 1.5 mlU/L. "Subclinical" hypothyroidism refers to those patients with early or mild thyroid hypofunction manifested as slight elevations of thyrotropin (approximately 4-10 mlU/L) although serum thyroxine (T4) and triiodothyronine (T3) levels are within their reference ranges. The entity is somewhat controversial in regard to its consequences if left untreated, and whether or not we should be screening patients, at least susceptible populations, for the condition. Reports indicate an association between subclinical hypothyroidism and poor outcomes of pregnancy, as well as dyslipidemias, atherogenesis, and increased mortality in the long term. We believe these consequences are sufficiently compelling to warrant screening and treatment with levothyroxine when found to halt progression to overt hypothyroidism, and improve symptoms, pregnancy outcomes, lipid abnormalities, and cardiovascular function.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall that hypothyroidism is a common disease in women, has many protean manifestations, and can be successfully diagnosed and treated; explain that the condition of subclinical hypothyroidism can be diagnosed and if treated can prevent many untoward complications; and state that there should be heightened awareness of the disease so that proper screening tests can be performed.