Benefits of thyrotropin suppression versus the risks of adverse effects in differentiated thyroid cancer

Liquid liothyronine to obtain target TSH in differentiated thyroid cancer patients

In the last ten years a liquid formulation of liothyronine (L-T3) became available. To date, no studies on its systematic use have been reported. This study is aimed at assessing the reliability of liquid L-T3 in achieving target TSH in patients with differentiated thyroid cancers (DTC). Twenty-one high risk DTC patients in whom levothyroxine treatment up to 2.0 μg/kg/day did not suppress TSH levels (i.e. >0.1 mIU/L) were selected. Maintaining the same L-T4 dose, they started to assume liquid L-T3 at an initial fixed dose of 3.55 μg (5 drops). Further adjustments of L-T3 dose were tailored according to individual assessment. Initial serum TSH ranged from 0.8 to 12.0 mIU/L, when patients assumed high dose of L-T4 alone. Following the addition of a daily single dose of 3.55 μg L-T3, the target TSH was attained in five patients (23.8%). After increasing L-T3 dose up to a mean of 7.3±3.4 μg/day all patients reached target serum TSH (<0.1 mIU/L). The mean individual L-T3 dose was significantly correlated with the body weight and was 0.11±0.04 μg/kg/day (p=0.013). Mean L-T4:L-T3 ratio was 21:1. No patients showed skewed free-T3 or free-T4 values, neither experienced discomfort nor reported adverse events. Liquid L-T3 can be useful to achieve optimal TSH suppression in high risk DTC with not suppressed TSH on L-T4 alone. This formulation allows an individual tailoring of L-T3, minimizing risks of side effects as well as of overtreatment in these clinical conditions.

Thyroxine replacement: a clinical endocrinologist's viewpoint

BACKGROUND

Hypothyroidism affects 2-5% of the general population. Patients with uncorrected disease suffer significant morbidity and have an increased risk of cardiovascular disease and neurocognitive impairment. Levothyroxine, the treatment of choice, is inexpensive, easy to administer and in most cases restores well-being while normalizing thyroid function. However, 30-50% of individuals on levothyroxine are either over-treated or under-treated and others remain dissatisfied with treatment despite achieving thyroid hormone concentrations within the laboratory reference interval.

METHODS

This review is based on a systematic search of the literature for controlled trials, systematic reviews, guideline papers and cohort studies addressing best practice in thyroid hormone replacement.

RESULTS

Recent decades have seen improvements in patient management strategies driven by a better appreciation of levothyroxine pharmacokinetics. However, aspects of therapy such as the optimal timing of medication, strategies to overcome treatment non-adherence and target thyroid stimulating hormone concentrations in pregnancy and in patients with differentiated thyroid cancer remain challenging. Furthermore, there is now a substantial body of literature on common genetic variations in the deiodinases and thyroid hormone transporters and their role in the local regulation of thyroid hormone delivery. The benefits of combination therapy with liothyronine and levothyroxine are uncertain, and while it is theoretically probable that subsets of genetically predisposed individuals will benefit from combination therapy the existing evidence is as yet limited.

CONCLUSION

Despite the availability of thyroid hormone replacement for more than a century, there are still substantial challenges in practice and opportunities to improve treatment outcomes.

Effects of Levothyroxine Replacement or Suppressive Therapy on Energy Expenditure and Body Composition

BACKGROUND

Thyrotropin (TSH)-suppressive doses of levothyroxine (LT4) have adverse effects on bone and cardiac function, but it is unclear whether metabolic function is also affected. The objective of this study was to determine whether women receiving TSH-suppressive LT4 doses have alterations in energy expenditure or body composition.

METHODS

This study was a cross-sectional comparison between three groups of women: 26 women receiving chronic TSH-suppressive LT4 doses, 80 women receiving chronic replacement LT4 doses, and 16 untreated euthyroid control women. Subjects underwent measurements of resting energy expenditure (REE), substrate oxidation, and thermic effect of food by indirect calorimetry; physical activity energy expenditure by accelerometer; caloric intake by 24-hour diet recall; and body composition by dual X-ray absorptiometry.

RESULTS

REE per kilogram lean body mass in the LT4 euthyroid women was 6% lower than that of the LT4-suppressed group, and 4% lower than that of the healthy control group (p = 0.04). Free triiodothyronine (fT3) levels were directly correlated with REE, and were 10% lower in the LT4 euthyroid women compared with the other two groups (p = 0.007). The groups of subjects did not differ in other measures of energy expenditure, caloric intake, or body composition.

CONCLUSIONS

LT4 suppression therapy does not adversely affect energy expenditure or body composition in women. However, LT4 replacement therapy is associated with a lower REE, despite TSH levels within the reference range. This may be due to lower fT3 levels, suggesting relative tissue hypothyroidism may contribute to impaired energy expenditure in LT4 therapy.

The effect of thyroid stimulating hormone suppressive therapy on bone geometry in the hip area of patients with differentiated thyroid carcinoma

Subclinical hyperthyroidism has been reported to increase the fracture risk. However, the effect of thyroid stimulating hormone (TSH) suppressive therapy on bone geometry in the hip area of patients with differentiated thyroid carcinoma (DTC) is still unclear. The aim of this study was to investigate the effect of TSH suppression on bone geometry in the hip area of pre- and postmenopausal women with DTC. We conducted a retrospective cohort study including 99 women with DTC (25 pre- and 74 postmenopausal) who had received TSH suppressive therapy for at least 3years and 297 control subjects (75 and 222, respectively) matched for sex and age. Bone mineral density (BMD) in the spine and hip area and bone geometry at the femoral neck measured by dual energy X-ray absorptiometry (DXA) were compared between patients and controls. The association between thyroid hormone and bone parameters was investigated. All analyses of bone parameters were adjusted for age, body mass index, and serum calcium levels. In premenopausal subjects, TSH suppressive therapy was not associated with poor bone parameters. In postmenopausal subjects, patients with DTC undergoing TSH suppression showed lower cross-sectional moment of inertia (CSMI), cross-sectional area, and section modulus and thinner cortical thickness at the femoral neck than those of control subjects, whereas their femoral neck BMD was comparable with controls. Total hip BMD was lower in postmenopausal patients than in controls. CSMI and section modulus at the femoral neck were independently associated with serum free T4 levels in postmenopausal patients. The difference in femoral neck bone geometry between patients and controls was only apparent in postmenopausal DTC patients with free T4 >1.79ng/dL (23.04pmol/l), and not in those with free T4 levels ≤1.79ng/dL (23.04pmol/l). TSH suppression in postmenopausal DTC patients was associated with decreased bone strength by altering bone geometry rather than BMD in the hip area, especially the femoral neck. This alteration in bone quality was observed only in patients with free T4 levels above the upper normal limit.

MECHANISMS IN ENDOCRINOLOGY: Impact of isolated TSH levels in and out of normal range on different tissues

Routine treatment of thyroid cancer (TC) includes long-term suppression of TSH. The necessity of this treatment in low- and intermediate-risk patients as well as the extent of TSH suppression is currently under discussion. A literature search was performed to illustrate the role of TSH in extrathyroidal cells and to identify potential reasons for different effects of exogenously suppressed and endogenously low TSH levels. Although adverse effects of subnormal and supranormal TSH blood levels on heart and brain have not been consistently found, studies show a clear negative effect of suppressed TSH levels on bone mineral density. Experimental data also support an important role of TSH in the immune system. The ability of levothyroxine (l-T4) to regulate TSH levels and triiodothyronine levels in a physiological manner is limited. Reduction of circadian changes in TSH levels, decrease of thyroid hormone-binding proteins, prevention of potential compensatory increases of TSH levels (e.g., in old age), and unresponsiveness of TSH-producing cells to TRH on l-T4 treatment might cause adverse effects of suppressed TSH levels. In view of the adverse effects of aggressive TSH suppression, achieving the suggested levels of TSH between 0.9 and 1 mU/l in the treatment of low-to-intermediate risk TC patients appears justified.

Effect of Thyrotropin Suppression Therapy on Bone in Thyroid Cancer Patients

BACKGROUND

The thyroid cancer incidence is rising. Despite current guidelines, controversy exists regarding the degree and duration of thyrotropin suppression therapy. Also, its potential skeletal effects remain a concern to physicians caring for thyroid cancer patients. We conducted a review of published data to evaluate existing studies focusing on the skeletal effects of thyrotropin suppression therapy in thyroid cancer patients.

MATERIALS AND METHODS

A systematic search of the PubMed, Ovid/Medline, and Cochrane Central Register of Controlled Trials databases was conducted. The retained studies were evaluated for methodological quality, and the study populations were categorized into premenopausal women, postmenopausal women, and men.

RESULTS

Twenty-five pertinent studies were included. Seven studies were longitudinal and 18 were cross-sectional. Of the 25 included studies, 13 were assigned an excellent methodological quality score. Three of 5 longitudinal studies and 3 of 13 cross-sectional studies reported decreased bone mineral density (BMD) in premenopausal women; 2 of 4 longitudinal studies and 5 of 13 cross-sectional studies reported decreased BMD in postmenopausal women. The remaining studies showed no effect on BMD. The only longitudinal study of men showed bone mass loss; however, cross-sectional studies of men did not demonstrate a similar effect.

CONCLUSION

Studies to date have yielded conflicting results on the skeletal effects of thyrotropin suppression therapy and a knowledge gap remains, especially for older adults and men. Existing data should be cautiously interpreted because of the variable quality and heterogeneity. Identifying groups at risk of adverse effects from thyrotropin suppression therapy will be instrumental to providing focused and tailored thyroid cancer treatment.

IMPLICATIONS FOR PRACTICE

The standard treatment for thyroid cancer includes total thyroidectomy with or without radioactive iodine ablation, often followed by thyrotropin suppression therapy. Despite current guidelines, controversy exists regarding the degree and duration of thyrotropin suppression therapy, and discordant results have been reported on its adverse effects on bone. The present review provides physicians with existing data on the skeletal effects of thyrotropin suppression therapy, highlighting the need for further research to identify the groups at risk of adverse skeletal effects. This knowledge will aid in developing tailored thyroid cancer treatment.

Thyroid Hormone Replacement in Patients Following Thyroidectomy for Thyroid Cancer

Thyroid hormone replacement therapy in patients following thyroidectomy for thyroid cancer, although a potentially straightforward clinical problem, can present the clinician and patient with a variety of challenges. Most often the problems are related to the dose and preparation of thyroid hormone (TH) to use. Some patients feel less well following thyroidectomy and/or radioiodine ablation than they did before their diagnosis. We present evidence that levothyroxine (L-T4) is the preparation of choice, and keeping the thyroid-stimulating hormone (TSH) between detectable and 0.1 mU/L should be the standard of care in most cases. In unusual circumstances, when the patient remains clinically hypothyroid despite a suppressed TSH, we acknowledge there may be as yet unidentified factors influencing the body's response to TH, and individualized therapy may be necessary in such patients.

The Effect of Levothyroxine Discontinuation Timing on Postoperative Hypothyroidism after Hemithyroidectomy for Papillary Thyroid Microcarcinoma

Objective. No previous studies regarding the appropriate timing of thyroid hormone discontinuation after hemithyroidectomy have been published. This study aimed to identify the appropriate timing for levothyroxine discontinuation after hemithyroidectomy among patients with papillary thyroid microcarcinoma (PTMC). Methods. This study retrospectively evaluated 304 patients who underwent ≥1 attempt to discontinue levothyroxine after hemithyroidectomy for treating PTMC between January 2008 and December 2013. Fifty-three patients were excluded because of preoperative hypothyroidism or hyperthyroidism, a history of thyroid hormone or antithyroid therapy, no available serological data, or a postoperative follow-up of <24 months. We evaluated the associations of successful levothyroxine discontinuation with patient age, sex, preoperative serological data, underlying thyroid gland histopathology, anteroposterior diameter of the residual thyroid gland, number of discontinuation attempts, and initial discontinuation timing. Results. Among the 251 included patients, 125 patients (49.8%) achieved successful levothyroxine discontinuation during the follow-up period after hemithyroidectomy. There was a significant difference in the outcomes for patients who underwent an initial discontinuation attempt at ≤3 months and ≥4 months after hemithyroidectomy (p < 0.001). There were significant differences in the discontinuation outcomes according to underlying thyroid histopathology (p = 0.001), preoperative thyroid-stimulating hormone levels (p < 0.001), and number of discontinuation attempts (p < 0.001). Conclusions. Among patients with PTMC, the initial levothyroxine discontinuation attempt is recommended at ≥4 months after hemithyroidectomy.

2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the American Thyroid Association's (ATA's) guidelines for the management of these disorders were revised in 2009, significant scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles on adults were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations for therapeutic interventions. We developed a similarly formatted system to appraise the quality of such studies and resultant recommendations. The guideline panel had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, use of molecular markers, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to screening for thyroid cancer, staging and risk assessment, surgical management, radioiodine remnant ablation and therapy, and thyrotropin suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using imaging and serum thyroglobulin, thyroid hormone therapy, management of recurrent and metastatic disease, consideration for clinical trials and targeted therapy, as well as directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

Follicular cell-derived thyroid cancer

Follicular cell-derived thyroid cancers are derived from the follicular cells in the thyroid gland, which secrete the iodine-containing thyroid hormones. Follicular cell-derived thyroid cancers can be classified into papillary thyroid cancer (80-85%), follicular thyroid cancer (10-15%), poorly differentiated thyroid cancer (<2%) and undifferentiated (anaplastic) thyroid cancer (<2%), and these have an excellent prognosis with the exception of undifferentiated thyroid cancer. The advent and expansion of advanced diagnostic techniques has driven and continues to drive the epidemic of occult papillary thyroid cancer, owing to overdiagnosis of clinically irrelevant nodules. This transformation of the thyroid cancer landscape at molecular and clinical levels calls for the modification of management strategies towards personalized medicine based on individual risk assessment to deliver the most effective but least aggressive treatment. In thyroid cancer surgery, for instance, injuries to structures outside the thyroid gland, such as the recurrent laryngeal nerve in 2-5% of surgeries or the parathyroid glands in 5-10% of surgeries, negatively affect quality of life more than loss of the expendable thyroid gland. Furthermore, the risks associated with radioiodine ablation may outweigh the risks of persistent or recurrent disease and disease-specific mortality. Improvement in the health-related quality of life of survivors of follicular cell-derived thyroid cancer, which is decreased despite the generally favourable outcome, hinges on early tumour detection and minimization of treatment-related sequelae. Future opportunities include more widespread adoption of molecular and clinical risk stratification and identification of actionable targets for individualized therapies.

Determinants of long-term quality of life in patients with differentiated thyroid carcinoma - a population-based cohort study in Sweden

BACKGROUND

Although differentiated thyroid cancer (DTC) has an excellent prognosis and a low incidence of recurrence, lifelong follow-up and medication might be needed. The aim of this study was to clarify how living with a cancer diagnosis for many years affects health-related quality of life (HRQoL) in DTC patients in Sweden.

MATERIAL AND METHODS

From the national all-encompassing population-based Swedish Cancer Registry, 353 patients diagnosed with DTC between 1995 and 1998 were identified and invited to answer the HRQoL questionnaire SF-36 and a study-specific questionnaire, 14-17 years after their diagnosis. Data were compared with a reference population as well between subgroups of patients.

RESULTS

Of the patients with DTC, 279 (79%) answered the questionnaires. In all, only 19 (7%) reported a recurrence, however, as many as 134 (48%) stated that they still had concerns about having a recurrence. The HRQoL in those with a recurrence was significantly lower than those without concerns of a recurrence in five of eight domains (p < 0.001-0.049). Similarly, patients with concerns of a recurrence reported poorer HRQoL than those without concerns, with significantly lower values in five domains (p < 0.001-0.008). Those few who stated that their disease had given them a negative view on life reported poor HRQoL in all eight domains (p < 0.001-0.030).

CONCLUSIONS

Even if DTC comes with an excellent prognosis, almost half of the patients, fully 15 years after diagnosis, worried about a recurrence which negatively impacted their HRQoL. Awareness among healthcare practitioners might improve information, supportive care and, in the end, the patient's HRQoL.

Patients with Papillary Thyroid Carcinoma at Intermediate Risk of Recurrence According to American Thyroid Association Criteria Can Be Reclassified as Low Risk When the Postoperative Thyroglobulin Is Low

BACKGROUND

According to American Thyroid Association (ATA), all patients with papillary thyroid carcinoma (PTC) should initially be classified regarding the risk of tumor recurrence. If a very high postoperative thyroglobulin (Tg) classifies patients as high risk of recurrence, it is reasonable to hypothesize that, at the other extreme, a low Tg may reclassify patients from intermediate to low risk. The objective of this study was to evaluate the rate of persistent/recurrent disease in intermediate-risk patients with low postoperative (before 131I) Tg, thereby evaluating whether these patients can be reclassified as low risk based on this finding already at the time of initial therapy rather than one to two years after radioiodine therapy.

METHODS

A total of 181 patients with the following characteristics were evaluated: (i) diagnosis of PTC; (ii) submitted to total thyroidectomy with lymph node dissection in the case of a suspicion of metastases based on preoperative ultrasonography (US) or perioperative evaluation (cN1); (iii) apparently without persistent tumor after surgery; (iv) a postoperative stimulated Tg (sTg) ≤2 ng/mL and negative anti-Tg antibodies (TgAb); and (v) considered to be at intermediate risk by ATA criteria.

RESULTS

When evaluated 9-12 months after radioiodine therapy, 170 patients (94%) had a sTg <1 ng/mL and negative TgAb and a negative neck US (excellent response). Ten patients (5.5%) had a sTg >1 ng/mL (≤2 ng/mL) in the absence of apparent disease detected by imaging methods (indeterminate response). US detected cervical lymph node metastases (not detected at the time of 131I therapy) in one patient (incomplete structural response). During follow-up, recurrence was observed in 5/180 (2.7%) patients without apparent disease in the initial assessment. Thus, persistent or recurrent disease occurred in only 3.3% of cases. The 175 patients without tumor persistence/recurrence were not submitted to any additional therapy, and all had a Tg/thryoxine <1 ng/mL in the last assessment. There was no case of death related to the disease.

CONCLUSIONS

This study suggests that intermediate-risk patients (according to ATA criteria) with a postoperative sTg ≤2 ng/mL can be reclassified as low risk already at the time of initial therapy.

[What's new in follicular thyroid cancer management in 2014?]

The American Thyroid Association has presented new guidelines for the management of thyroid cancer. These guidelines tend to appreciate more accurately the individual risk of patients, to adapt accordingly the treatment and the follow up. The initial risk stratification has been completed, especially precising the risk of N1 patients, follicular thyroid cancers, and the prognostic impact of molecular markers. Indications, doses and modalities of radioiodine (RAI) have been reevaluated, restricting its utilization in order to avoid overtreatment of low risk patients. Moreover the response to initial treatment allows to restratify the risk of the patients, and to adapt the monitoring and the thyroid hormone therapy management. The risk of suppressive thyroid hormone therapy has also to be considered. Concerning advanced thyroid cancer, prognosis is mainly depending on its RAI sensitivity. The systemic treatment of progressive, threatening refractory cancers is nowadays based on targeted therapy. However none of these treatments has demonstrated an improvement in overall survival, and side effects are frequent. Fagin et al presented promising results concerning short term treatment with selective inhibitors of the MAPK pathway, able to partially restore RAI sensitivity of refractory lesions in murine models, and recently in human patients.

Low BMI and low TSH value as risk factors related to lower bone mineral density in postmenospausal women under levothyroxine therapy for differentiated thyroid carcinoma

Objective

Treatment of differentiated thyroid carcinoma (DTC) includes suppression of TSH with levothyroxine therapy, which may negatively influence bone mineral density (BMD), but the effects are controversial. We aimed to evaluate the relationship between TSH-suppressive therapy and BMD in postmenopausal women with DTC.

Methodology

Cross-sectional study that assessed BMD by densitometry and risk factors for decreased BMD in 109 postmenopausal women under TSH-suppressive therapy for DTC, compared to an age-matched euthyroid women control group. Conditions that might have affected BMD were exclusion criteria.

Results

Patients were 58.4 ± 8.3 years-old, mean serum TSH was 0.21 ± 0.28μIU/ml. In BMD evaluation, T-scores were −1.09 ± 1.43 SD (lumbar spine) and −0.12 ± 1.18 SD (total femur). No significant differences were found between lumbar or femoral T-scores of patients and control group. Multivariate logistic regression analysis evidenced that low BMI and low mean TSH levels (assessed in the year of BMD measurement) were factors significantly related to lower lumbar and spinal BMD.

Conclusion

Although low TSH levels and low BMI were correlated with lower BMD, it was not observed an increased prevalence of osteopenia or osteoporosis in this cohort of post-menopausal women under levothyroxine treatment for DTC, when compared to age-matched control women. Nevertheless, such risk factors should be carefully observed in individual patients at high risk of decrease in BMD.

An examination of myth: a favorable cardiovascular risk-benefit analysis of high-dose thyroid for affective disorders

INTRODUCTION

High dose thyroid (HDT) is included in major treatment guidelines for the treatment of bipolar disorders. Yet it is seldom used partly based on perceived cardiovascular risks. The cardiovascular risks of HDT are examined.

METHODS

A literature search was conducted for the cardiovascular risks of HDT and for comparisons sake psychiatric medications. Case reports of atrial fibrillation (afib) associated with HDT are reported.

RESULTS

While hyperthyroidism is a significant cardiovascular risk factor causing a 20% premature death rate, HDT treatment does not appear to be of significant cardiovascular risk. HDT differs from hyperthyroidism in significant ways. The sequela of hyperthyroidism are increasingly tied to autoimmune complications which are absent with HDT. Equating hyperthyroidism with HDT is incorrect. The five case reports of HDT treatment associated with afib were potentially caused by other factors. If HDT increases the risks of afib, monitoring for afib would minimizes the risk. Even in overt hyperthyroidism the risk of other arrhythmias are minimal. When compared to many psychiatric medications HDT is as safe or safer.

LIMITATIONS

There are no direct studies of cardiovascular risks of HDT for affective patients. High tolerance of a medication does not necessarily imply lack of risk. The five case reports were spontaneous, other cases may not have been reported.

CONCLUSION

The cardiovascular risks of HDT appear to be low. HDT is at least as safe as or safer than many psychiatric medications. It is effective and well tolerated.

Bone disease in hypoparathyroidism

Hypoparathyroidism is a rare disorder that may be acquired or inherited. Postsurgical hypoparathyroidism is responsible for the majority of acquired hypoparathyroidism. Bone disease occurs in hypoparathyroidism due to markedly reduced bone remodeling due to the absence or low levels of parathyroid hormone. Chronically reduced bone turnover in patients with hypoparathyroidism typically leads to higher bone mass than in age- and sex-matched controls. Whether this increased bone density reduces fracture risk is less certain, because while increased bone mineralization may be associated with increased brittleness of bone, this does not appear to be the case in hypoparathyroidism. Treatment of hypoparathyroidism with recombinant parathyroid hormone may reduce bone mineral density but simultaneously strengthen the mechanical properties of bone.

Thyrotropin suppression increases the risk of osteoporosis without decreasing recurrence in ATA low- and intermediate-risk patients with differentiated thyroid carcinoma

BACKGROUND

Levothyroxine suppression of thyrotropin (TSH) is broadly applied to patients with thyroid cancer despite lack of consensus on the optimal TSH concentration necessary to reduce cancer recurrence while minimizing toxicity from subclinical hyperthyroidism. The objectives of this study were to examine the beneficial effects and the cardiac and skeletal toxicity of TSH suppression in well-differentiated thyroid carcinoma (DTC).

METHODS

A total of 771 patients (569 women) at ATA low or intermediate risk of recurrence, with a mean age of 48±14 years, and undergoing total thyroidectomy at a tertiary care center between 2000 and 2006 were followed for a median of six and a half years. They were divided into a suppressed TSH group (median TSH ≤0.4 mIU/L) and a nonsuppressed group (median TSH >0.4 mIU/L). Structural recurrence of thyroid cancer, postoperative atrial fibrillation (AF), and osteoporosis were examined in the two groups. Osteoporosis was only examined in women.

RESULTS

A total of 43/771 (5.6%) patients recurred, 29/739 (3.9%) patients were diagnosed with postoperative osteoporosis, and 17/756 (2.3 %) were diagnosed with postoperative AF. Despite similar rates of recurrence (HR 1.02, p=0.956 [CI 0.54-1.91]), patients treated to a median TSH ≤0.4 mIU/L were at increased postoperative risk of a composite outcome of AF and osteoporosis (HR 2.1, p=0.05 [CI 1.001-4.3]) compared to those not suppressed. A differential risk of AF alone (HR 0.78, p=0.63 [CI 0.3-2.1]) was not detected, but postoperative osteoporosis was increased among women with a suppressed TSH compared to those not suppressed (HR 3.5, p=0.023 [CI 1.2-10.2]). The increased risk of postoperative osteoporosis disappeared when the patient's median TSH was maintained around 1 mIU/L.

CONCLUSION

TSH suppression significantly increases the risk of postoperative osteoporosis without changing tumor recurrence in ATA low- and intermediate-risk patients with DTC. Future interventions should focus on avoiding harm in indolent disease.

The effects of thyrotropin-suppressing therapy on bone metabolism in patients with well-differentiated thyroid carcinoma

Studies on the effects of levothyroxine (LT4) therapy on bone and bone metabolism have yielded conflicting results. This 1-year prospective study examined whether LT4 in patients with well-differentiated thyroid carcinoma (DTC) is a risk factor for bone mass loss and the subsequent development of osteoporosis. We examined 93 patients with DTC over 12months after initiating LT4 therapy (early postoperative period). We examined another 33 patients on long-term LT4 therapy for DTC (late postoperative period). Dual energy X-ray absorptiometry was performed at baseline and after 1year. The mean bone losses during the early postoperative period in the lumbar spine, femoral neck, and total hip, calculated as the percentage change between levels at baseline and 12months, were -0.88, -1.3 and -0.81%, respectively. Bone loss was more evident in postmenopausal women (lumbar spine -2.1%, femoral neck -2.2%, and hip -2.1%; all P<0.05). We compared the changes in annual bone mineral density (BMD) in postmenopausal women according to calcium/vitamin D supplementation. Bone loss tended to be higher in the postmenopausal women receiving no supplementation. There was no decrease in BMD among patients during the late postoperative period. The mean bone loss was generally greater in the early than in the late postoperative group, and this was significant at the lumbar spine (P=0.041) and femoral neck (P=0.010). TSH-suppressive levothyroxine therapy accelerates bone loss, predominantly in postmenopausal women and exclusively during the early post-thyroidectomy period.

Volumetric bone mineral density and bone geometry assessed by peripheral quantitative computed tomography in women with differentiated thyroid cancer under TSH suppression

OBJECTIVE

TSH suppression therapy in patients with differentiated thyroid cancer (DTC) has been associated with adverse effects on areal bone mineral density (aBMD) only in postmenopausal women. The purpose of study was to examine the effect of TSH suppression therapy on skeletal integrity using peripheral quantitative computed tomography (pQCT) at the radius and tibia in pre- and postmenopausal women with DTC and controls.

STUDY DESIGN AND PATIENTS

Subjects included 80 women with DTC (40 pre- and 40 postmenopausal) and 89 (29 and 60, respectively) controls. pQCT was performed at the radius and tibia, Dual-energy X-ray absorptiometry (DXA) at the hip and lumbar spine, while samples were taken for calciotropic hormones and bone markers.

RESULTS

No differences were observed concerning aBMD by DXA. In premenopausal women, there were no significant differences concerning vBMD, while cortical thickness was higher at the radius in patients with DTC (P < 0·01) compared with controls. In postmenopausal women with DTC trabecular bone mineral content (BMC), area and vBMD were lower at the radius (all P < 0·05), while at the tibia trabecular BMC and vBMD were lower at the mixed transition zone (14% from the distal end, P < 0·05) compared with controls. Cortical thickness was lower at the radius (P < 0·01) in postmenopausal patients compared with controls. Serum CTX was higher in postmenopausal women with DCT (P < 0·01), while in premenopausal patients, parathyroid hormone (PTH) was lower (P = 0·01) compared with controls.

CONCLUSIONS

TSH suppression therapy is associated with higher bone resorption only in postmenopausal women; this adversely affects trabecular and cortical bone properties especially at nonweight-bearing sites such as the radius.

A systematic review of randomized controlled trials for management of persistent post-treatment fatigue in thyroid cancer survivors

BACKGROUND

Fatigue that persists post-treatment is commonly reported by thyroid cancer (TC) survivors.

METHODS

A systematic review of published English language randomized controlled trials (RCTs) on interventions for management of persistent post-treatment fatigue in TC was conducted. This review excluded studies on short-term interventions used in preparation for radioactive iodine diagnostic scans or treatment. An electronic search was executed in six databases and supplemented by a hand search. Two reviewers independently reviewed all citations from the electronic search and relevant full-text studies. Two abstractors independently critically appraised included studies and abstracted the data. The data were qualitatively summarized.

RESULTS

A total of 1086 unique citations and 25 full-text studies were reviewed. Four studies summarizing the results of three RCTs were included. The interventions included: combination triiodothyronine with levothyroxine (L-T4) therapy compared to L-T4 alone (one RCT), reduction in degree of thyrotropin (TSH) suppression using L-T4 compared to maintenance of TSH suppression (one RCT), and supervised exercise compared to inactivity (two RCTs examining different fatigue outcomes in same population). Trial duration ranged from 10 weeks to six months. All trials had limitations, and the number of TC survivors included in respective RCTs ranged from 15 to 36. Hormonal treatment RCTs had mixed fatigue outcome results within respective trials. However, multiple measures suggesting improvement in fatigue were reported following the exercise intervention.

CONCLUSIONS

There is paucity of RCTs to guide evidence-based management of persistent post-treatment fatigue in TC survivors. RCTs of interventions for prevention or treatment of fatigue in TC survivors are needed.

Aortic stiffness and left ventricular function in patients with differentiated thyroid cancer

OBJECTIVE

The aim of this study was to investigate aortic stiffness and left ventricular (LV) systolic and diastolic function in patients with differentiated thyroid cancer (DTC) on thyroxine (L-T4) therapy and after L-T4 withdrawal to assess the cardiovascular impact of long-term subclinical hyperthyroidism and short-term overt hypothyroidism.

METHODS

Twenty-four patients who had had total thyroidectomy and radioiodine ablation for differentiated thyroid cancer were studied on two occasions: on TSH suppressive L-T4 therapy (sTSH 0.24 ± 0.11 mU/L), and 4 weeks after L-T4 withdrawal (sTSH 89.82 ± 29.36 mU/L). Echocardiography was performed and thyroid function, serum thyroglobulin, lipid parameters, homocystine, C-reactive protein, fibrinogen and von Willebrand factor activity (vWF) were measured. Twenty-two healthy volunteers matched for age and sex served as euthyroid controls.

RESULTS

Aortic stiffness was increased both in hypothyroidism (6.04 ± 2.88 cm(2)/dyn/10(3), p < 0.05) and subclinical hyperthyroidism (9.27 ± 4.81 cm(2)/dyn/10(3), p < 0.05) vs. controls (3.92 ± 1.84 cm(2)/dyn/10(3)). Subclinical hyperthyroidism had a more marked effect (p < 0.05). LV dimensions and ejection fractions were similar before and after L-T4 withdrawal. The E'/A' was higher in euthyroid controls (1.34 ± 1.02) as compared to both subclinical hyperthyroidism (1.0 ± 0.14, p < 0.05) and overt hypothyroidism (1.13 ± 0.98, p < 0.05). Change of aortic stiffness correlated with change of free-thyroxine (fT4), vWF and fibrinogen levels in a positive manner.

CONCLUSION

Long-term thyrotropin-suppression therapy has continuous adverse effects on the arterial wall. The degree of TSH suppression in patients with DTC should be kept at the possible minimum, based on individually determined potential benefits and risks of treatment, especially in patients with cardiovascular co-morbidities.

Autophagy in thyroid cancer: present knowledge and future perspectives

Thyroid cancer is the most common endocrine malignancy. Despite having a good prognosis in the majority of cases, when the tumor is dedifferentiated it does no longer respond to conventional treatment with radioactive iodine, the prognosis worsens significantly. Treatment options for advanced, dedifferentiated disease are limited and do not cure the disease. Autophagy, a process of self-digestion in which damaged molecules or organelles are degraded and recycled, has emerged as an important player in the pathogenesis of different diseases, including cancer. The role of autophagy in thyroid cancer pathogenesis is not yet elucidated. However, the available data indicate that autophagy is involved in several steps of thyroid tumor initiation and progression as well as in therapy resistance and therefore could be exploited for therapeutic applications. The present review summarizes the most recent data on the role of autophagy in the pathogenesis of thyroid cancer and we will provide a perspective on how this process can be targeted for potential therapeutic approaches and could be further explored in the context of multimodality treatment in cancer and personalized medicine.

Thyroglobulin test at 3 weeks after surgery in well-differentiated thyroid cancer and its predictive value: the role of endocrine–metabolic status

Aim & methods: The present pilot study included 50 differentiated thyroid cancer (DTC) patients (mean age: 45.8 ± 1.8 years, range: 18–73 years) who were followed after surgery for in average 30.0 ± 2.6 months. All patients were subdivided into two groups as having either <2 ng/ml or ≥2 ng/ml blood thyroglobulin level 3 weeks after the operation (3-WTT). Results: Subsequent tumor progression was revealed more often in patients with higher thyroglobulinemia (≥2 ng/ml) in both low- and high-risk DTC groups. Patients with high-risk DTC and 3-week thyroglobulin levels ≥2 ng/ml were more likely to have a higher pre-surgical thyrotropin (TSH) levels. On the contrary, patients with low-risk DTC and 3-week thyroglobulin level ≥2 ng/ml demonstrated tendency to higher preoperative serum insulin levels and higher BMI. Conclusion: These differential findings could suggest that, whereas maximal suppression of TSH is reasonable in high-risk DTC patients, in low-risk DTC patients, for whom this is not justified, a moderate TSH suppression supplemented by multivalent drugs, such as antidiabetic biguanide metformin, could be advised.

Recurrence of differentiated thyroid carcinoma during full TSH suppression: is the tumor now thyroid hormone dependent?

Well-standardized primary treatment and long-term management of differentiated thyroid carcinoma (DTC) include lowering or suppression of host thyrotropin (TSH) with exogenous L-thyroxine (T₄). This treatment recognizes the trophic action of TSH on DTC cells. Suppression of endogenous TSH with T₄ is continued in recurrent disease. However, T₄ can induce proliferation of follicular and papillary thyroid carcinoma cell lines and of other human carcinoma cells. The proliferative mechanism is initiated at a cell surface receptor for T₄ on integrin αvβ3, a receptor by which the hormone also inhibits p53-dependent apoptosis in tumor cells. In recurrent DTC with satisfactory suppression of endogenous TSH, we discuss here the possibility that the tumor is no longer TSH dependent and that T₄ has become a critical growth factor for the cancer.

How to manage patients with differentiated thyroid cancer and a rising serum thyroglobulin level

Serum thyroglobulin (sTg) is the marker for monitoring persistence/recurrence of differentiated thyroid cancer, in patients without sTg antibodies. Patients with undetectable basal sTg or peak sTg <2 ng/mL are cured with low risk to recur. Newly detectable level of sTg indicates the recurrence. The significance of increasing sTg in patients treated with emithyroidectomy or total-thyroidectomy but not ablated with radioiodine is undefined. A doubling time <1 year may be a poor prognostic factor, but this is more relevant in cases with high levels of sTg. Because of its sensitivity, neck ultrasound should be performed at any visit, especially when an increased sTg is seen.

Treatment with thyroid hormone

Thyroid hormone deficiency can have important repercussions. Treatment with thyroid hormone in replacement doses is essential in patients with hypothyroidism. In this review, we critically discuss the thyroid hormone formulations that are available and approaches to correct replacement therapy with thyroid hormone in primary and central hypothyroidism in different periods of life such as pregnancy, birth, infancy, childhood, and adolescence as well as in adult patients, the elderly, and in patients with comorbidities. Despite the frequent and long term use of l-T4, several studies have documented frequent under- and overtreatment during replacement therapy in hypothyroid patients. We assess the factors determining l-T4 requirements (sex, age, gender, menstrual status, body weight, and lean body mass), the major causes of failure to achieve optimal serum TSH levels in undertreated patients (poor patient compliance, timing of l-T4 administration, interferences with absorption, gastrointestinal diseases, and drugs), and the adverse consequences of unintentional TSH suppression in overtreated patients. Opinions differ regarding the treatment of mild thyroid hormone deficiency, and we examine the recent evidence favoring treatment of this condition. New data suggesting that combined therapy with T3 and T4 could be indicated in some patients with hypothyroidism are assessed, and the indications for TSH suppression with l-T4 in patients with euthyroid multinodular goiter and in those with differentiated thyroid cancer are reviewed. Lastly, we address the potential use of thyroid hormones or their analogs in obese patients and in severe cardiac diseases, dyslipidemia, and nonthyroidal illnesses.

Thyrotropin in the development and management of differentiated thyroid cancer

Thyrotropin (TSH) is the major regulator and growth factor of the thyroid. TSH may be important in the development of human thyroid cancer, with both suggestive animal models and clinical evidence, although definitive proof is still required. Applications for TSH in thyroid cancer management include TSH stimulation of radioiodine uptake, enhancement of biochemical monitoring through thyroglobulin measurement, and long-term suppression of TSH with supraphysiologic levothyroxine. This review synthesizes current knowledge of TSH in both the development and management of differentiated thyroid cancer.

The effects of levothyroxine replacement or suppressive therapy on health status, mood, and cognition

CONTEXT

TSH-suppressive doses of levothyroxine (L-T4) have adverse effects on bone and cardiac function, but it is unclear whether central nervous system function is also affected.

OBJECTIVE

The aim of the study was to determine whether women receiving TSH-suppressive L-T4 doses have decrements in health status, mood, or cognitive function.

DESIGN AND SETTING

A cross-sectional comparison was made among three groups of women in an academic medical center research clinic.

PATIENTS

Twenty-four women receiving chronic TSH-suppressive L-T4 doses, 35 women receiving chronic replacement L-T4 doses, and 20 untreated control women participated in the study.

INTERVENTIONS

Subjects underwent testing at a single outpatient visit.

MAIN OUTCOME MEASURES

We measured health status (SF-36), mood (Profile of Mood States, Symptom Checklist 90-R, Affective Lability Scale), and cognitive function (declarative memory [Paragraph Recall], working memory [N-back, Subject Ordered Pointing], motor learning [Pursuit Rotor, Motor Sequence Learning Test], and executive function [Letter Cancellation Test, Trail Making Test, Iowa Gambling Test]).

RESULTS

Women receiving TSH-suppressive or replacement L-T4 doses had decrements in health status and mood compared to healthy controls. These decrements were more pronounced in women receiving replacement, rather than suppressive, L-T4 doses. Memory and executive function were not affected in either treated group, compared to healthy controls.

CONCLUSIONS

Women receiving TSH-suppressive doses of L-T4 do not have central nervous system dysfunction due to exogenous subclinical thyrotoxicosis, but TSH-suppressed and L-T4-replaced women have slight decrements in health status and mood that may be related to self-knowledge of the presence of a thyroid condition or other uncharacterized factors. These mood alterations do not impair cognitive function.

Long-Term Cardiovascular Mortality in Patients With Differentiated Thyroid Carcinoma: An Observational Study

Purpose

The primary aim was to study the risk of cardiovascular mortality in patients with differentiated thyroid carcinoma (DTC). Secondary aims were to evaluate all-cause mortality and explore the relation between thyroid-stimulating hormone (TSH; also known as thyrotropin) level and these outcome parameters.

Patients and Methods

Subjects from two cohorts were retrospectively compared by Cox regression analyses; 524 patients with DTC and 1,572 sex- and age-matched controls from a large population-based study in the same geographic region.

Results

Mean age plus or minus standard deviation was 49 ± 14 years. Median follow-up was 8.5 years (interquartile range [IQR], 4.1 to 15.9 years) for patients with DTC and 10.5 years (IQR, 9.9 to 10.9 years) for controls. One hundred patients with DTC (19.1%) died, 22 (4.2%) as a result of cardiovascular disease, 39 (7.4%) as a result of DTC, and 39 (7.4%) as a result of other/unknown causes. Eighty-five controls (5.4%) died, 24 (1.5%) as a result of cardiovascular disease and 61 (3.9%) as a result of other/unknown causes. Patients with DTC had an increased risk of cardiovascular and all-cause mortality (hazard ratios [HRs], 3.35 [95% CI, 1.66 to 6.74] and 4.40 [95% CI, 3.15 to 6.14], respectively, adjusted for age, sex, and cardiovascular risk factors). Within the DTC group, TSH level was predictive for cardiovascular mortality; the adjusted HR was 3.08 (95% CI, 1.32 to 7.21) for each 10-fold decrease in geometric mean TSH level.

Conclusion

The risk of cardiovascular and all-cause mortality is increased in patients with DTC, independent of age, sex, and cardiovascular risk factors. A lower TSH level is associated with increased cardiovascular mortality, supporting the current European Thyroid Association and the American Thyroid Association guidelines of tempering TSH suppression in patients with low risk of cancer recurrence. Furthermore, patients with DTC may benefit from assessment and treatment of cardiovascular risk factors.

Serum thyrotropin concentration in children with isolated thyroid nodules

OBJECTIVE

To investigate the correlation between serum thyroid-stimulating hormone (TSH) concentration and nodule nature in pediatric patients with thyroid nodules, with the aim of identifying a marker able to differentiate benign and malignant nodules.

STUDY DESIGN

This was a retrospective analysis of serum TSH concentrations in a multicentric case series of 125 pediatric patients with benign and malignant thyroid nodules.

RESULTS

Of the 125 patients, 99 had benign thyroid nodules and 26 had differentiated thyroid cancer (24 papillary and 2 follicular). Final diagnosis was based on surgery in 57 cases and on a benign cytology plus clinical follow-up in 68 cases. Serum TSH concentration was significantly higher in patients with thyroid cancer compared with those with benign nodules (3.23 ± 1.59 mU/L vs 1.64 ± 0.99 mU/L; P < .001). Binary logistic regression analysis revealed that serum TSH was the sole predictor of malignancy (P < .001). Dividing the patient cohort into 5 groups based on serum TSH quintiles (TSH cutoffs 0.40, 1.00, 1.50, 1.80, and 2.80 mU/L), we observed that cancer prevalence increased in parallel with serum TSH (P < .001), with respective rates of 0%, 4%, 16%, 32%, and 52% in the 5 quintile groups.

CONCLUSION

Because cases with malignant nodules are most likely seen in the upper normal serum TSH range (ie, >2.8 mU/L), serum TSH concentration can serve as a predictor of thyroid cancer in pediatric patients with thyroid nodules and can inform the decision of when to submit patients to further investigation by cytology.

Combination L-T3 and L-T4 therapy for hypothyroidism

PURPOSE OF REVIEW

Because of the longstanding controversy regarding whether hypothyroid patients can be optimally replaced by treatment with levothyroxine (L-T4) alone, numerous studies have addressed potential benefits of combined therapy of triiodothyronine (T3) with L-T4. Results of these studies have failed to support a potential benefit of combined therapy. A strong argument for the addition of L-T3 to L-T4 monotherapy has been lacking until recent genetic studies indicated a rationale for such therapy among a small fraction of the hypothyroid patient population.

RECENT FINDINGS

Interest in this issue has focused on the importance of the deiodinases in maintaining the euthyroid state and the role of genetic polymorphisms in the deiodinase genes that would affect thyroid hormone concentrations in both blood and tissues. One such polymorphism in the D2 gene, Thr92Ala, is associated with reduced T4 to T3 activation in skeletal muscle and thyroid, linked to obesity and alterations in thyroid-pituitary feedback, and in responses to thyroid hormone treatment.

SUMMARY

Although our professional organizations continue to recommend L-T4 alone for the treatment of hypothyroidism, the possibility of a D2 gene polymorphism should be considered in patients on L-T4 monotherapy who continue to complain of fatigue in spite of dosage achieving low normal serum thyroid stimulating hormone levels. A suggestive clue to the presence of this polymorphism could be a higher than normal free T4/free T3 ratio. Clinicians could consider adding T3 as a therapeutic trial in selected patients. Future well controlled clinical trials will be required to more fully resolve the controversy.

Vitamin D3 levels and insulin resistance in papillary thyroid cancer patients

Both insulin resistance (IR) and vitamin D deficiency (VDD) are found to be associated with many cancer types. In this study, we evaluated the presence of IR and VDD in thyroid cancer patients based on controls. Total 344 papillary thyroid cancer and 116 controls were part of the study. Glucose, insulin, homeostasis model analysis-insulin resistance (HOMA-IR) (control group 2.12 ± 0.9 and patient group 3.6 ± 1.1; p < 0.0001), LDL were significantly high; HOMA-S and vitamin D3 levels (control group 19.11 ± 8 and patient group 17 ± 16; p = 0.004) were significantly low in the patient group. Vitamin D deficiency (64/108 in controls vs 166/235; p = 0.026) and insulin resistance (24/108; 115/235; p < 0.0001) were more frequent in papillary thyroid cancer patients. After regression analysis, tumor diameter showed significant association with log-HOMA-IR (B = 0.315; p = 0.017) and log-vitamin D3 (B = 0.207; p = 0.04). Vitamin D deficiency and insulin resistance frequencies show no difference between micro- and macropapillary thyroid cancers. Receiver operating characteristic curve shows the best cutoff point for tumor diameter showing that the presence of lymph node metastasis was 0.65 cm with 81.2 % sensitivity and 52 % specificity. Best cutoff point for the capsular invasion tumor diameter was 0.75 cm with 83.3 % sensitivity and 60.4 % specificity. No difference between follicular and classical type papillary thyroid carcinomas has been yet discovered. As a result, thyroid cancer patients are more insulin resistant and vitamin D3 deficient. Vitamin D3 levels and HOMA-IR index may affect tumor diameter. Tumor size that is lower than 1 cm (0.65-0.75 cm) may be related with capsular invasion and lymph node involvement.

Controversies in primary treatment of low-risk papillary thyroid cancer

In many parts of the world, incidence of papillary thyroid cancer is increasing faster than any other malignancy. Most papillary thyroid cancers that are diagnosed are small and are generally regarded as being low risk, with little or no effect on mortality. Papillary thyroid cancer is a clinical challenge because it is difficult to prove benefit from the traditional therapeutic triad for this disorder (ie, total thyroidectomy with or without prophylactic central neck dissection, radioiodine remnant ablation, and suppression of serum thyroid-stimulating hormone with levothyroxine). However, risk of disease recurrence might be reduced by these therapies in a subset of patients with more aggressive disease. In the past decade, professional societies and other groups have established evidence-based clinical practice guidelines for management of papillary thyroid cancer, but these efforts have been made difficult by a paucity of randomised controlled trials. In this review, we summarise epidemiological data for disease incidence, discuss some controversies in disease management, and outline a therapeutic framework founded in the best available medical evidence and existing recommendations from clinical practice guidelines.

Using body mass index to predict optimal thyroid dosing after thyroidectomy

BACKGROUND

Current postoperative thyroid replacement dosing is weight based, with adjustments made after thyroid-stimulating hormone values. This method can lead to considerable delays in achieving euthyroidism and often fails to accurately dose over- and underweight patients. Our aim was to develop an accurate dosing method that uses patient body mass index (BMI) data.

STUDY DESIGN

A retrospective review of a prospectively collected thyroid database was performed. We selected adult patients undergoing thyroidectomy, with benign pathology, who achieved euthyroidism on thyroid hormone supplementation. Body mass index and euthyroid dose were plotted and regression was used to fit curves to the data. Statistical analysis was performed using STATA 10.1 software (Stata Corp).

RESULTS

One hundred twenty-two patients met inclusion criteria. At initial follow-up, only 39 patients were euthyroid (32%). Fifty-three percent of patients with BMI >30 kg/m(2) were overdosed, and 46% of patients with BMI <25 kg/m(2) were underdosed. The line of best fit demonstrated an overall quadratic relationship between BMI and euthyroid dose. A linear relationship best described the data up to a BMI of 50. Beyond that, the line approached 1.1 μg/kg. A regression equation was derived for calculating initial levothyroxine dose (μg/kg/d = -0.018 × BMI + 2.13 [F statistic = 52.7, root mean square error of 0.24]).

CONCLUSIONS

The current standard of weight-based thyroid replacement fails to appropriately dose underweight and overweight patients. Body mass index can be used to more accurately dose thyroid hormone using a simple formula.

Management of differentiated thyroid cancer of the follicular epithelium

The incidence of thyroid cancer has been increasing in many countries over the last 30 years (from 3.6/100,000 people in 1973 to 8.7/100,000 people in 2002) while mortality has been slowly decreasing ( 1 , 2 ). The increase is mainly represented by papillary thyroid cancer, while follicular and anaplastic histotypes remained stable. It is a general opinion that the increase is attributable to better detection of small papillary carcinomas as a result of improved diagnostic accuracy (neck ultrasound and fine-needle aspiration cytology). Consequently, it is common experience in thyroid cancer referral centers that nearly 60%-80% of thyroid carcinomas detected nowadays are micropapillary thyroid carcinomas (less than 1 cm in size) carrying an excellent long-term prognosis. In view of this change in the presentation of the disease, the objective of thyroid cancer management should be aimed at achieving complete cure using the less aggressive diagnostic and therapeutic procedures.

Current recommendations for levothyroxine treatment of differentiated thyroid cancer patients are not properly implemented in clinical practice

BACKGROUND

Levothyroxine (L-T4) treatment aims to minimize the risk of differentiated thyroid cancer (DTC) recurrence and should be tailored to patient risk stratification and potential morbidity from adverse effects.

AIM

To evaluate the effectiveness of current recommendations on L-T4 treatment of DTC patients in clinical practice.

MATERIAL AND METHODS

We submitted to in-person interviews and revised the charts of 139 low-risk (LR) and 57 not-low-risk (NLR) DTC patients. A second evaluation made 24-60 months after surgery reclassified 131 patients who maintained (thyroglobulin) Tg≤2 ng/dl with no evidence of relapse/recurrence as LR, whereas the remaining 65 cases were considered NLR.

RESULTS

Only 27% LR patients were appropriately controlled; 18% were kept suppressed; 49% maintained serum TSH levels between 0.11-0.4 mU/l; 21% had TSH=2.5- 4.5 mU/l; and 12% TSH>4.5 mU/l. Among the NLR patients, 24 (37%) of the patients presented serum TSH levels above goal, including 13 (20%) patients with TSH>4.5 mU/l. There were 4 NLR elders whose TSH levels were kept between 0.41 and 4.5 for medical reasons; likewise, 28 NLR patients maintained with low but not undetectable serum TSH levels had cardiovascular and/or bone risk factors, but all the remaining 24 NLR patients were not adequately controlled because of poor treatment compliance. On the other hand, 45% of 152 inappropriately controlled patients presented risks for bone fractures, including 33 patients kept with low serum TSH levels without medical indication.

CONCLUSION

We concluded that guidelines are not adequately applied and alternative strategies aiming to increase adherence are urgently needed for DTC patients.

Natural history, diagnosis and management of subclinical thyroid dysfunction

Subclinical thyroid dysfunction (STD) represents a condition of slight thyroid hormone excess or deficiency, which may be associated with important adverse effects. This review will focus on the natural history, diagnosis and management of subclinical thyroid dysfunction. Since STD is only detected as a thyroid stimulating hormone (TSH) abnormality, it is essential to exclude transient causes of abnormal serum TSH before treating this disorder. Treatment of subclinical hyperthyroidism (SHyper) is recommended in elderly patients with undetectable serum TSH for the increased risk of atrial fibrillation, osteoporosis and bone fractures and for the higher risk of progression to overt disease. Treatment of subclinical hypothyroidism should be considered in patients with serum TSH above 10 mU/L for the increased risk of progression to overt hypothyroidism and the increased risk of coronary heart disease and heart failure events, which have been documented in patients with TSH increase above 10 mU/L. About 75% of patients with STD have mild dysfunction. The mild form of STD (low but detectable serum TSH in SHyper and mild increased serum TSH between 5 and 9 mU/L in SHypo is associated with a minor risk of disease progression to overt dysfunction. The best treatment for STD remains controversial. Treatment of the mild form of STD should be considered after evaluating the patients' age, the adverse risk factors, the potential beneficial effects of treating this disorder and any underlying co-morbidities. Mild SHypo should be treated in infertile and pregnant women.

Combination treatment with T4 and T3: toward personalized replacement therapy in hypothyroidism?

CONTEXT

Levothyroxine therapy is the traditional lifelong replacement therapy for hypothyroid patients. Over the last several years, new evidence has led clinicians to evaluate the option of combined T(3) and T(4) treatment to improve the quality of life, cognition, and peripheral parameters of thyroid hormone action in hypothyroidism. The aim of this review is to assess the physiological basis and the results of current studies on this topic.

EVIDENCE ACQUISITION

We searched Medline for reports published with the following search terms: hypothyroidism, levothyroxine, triiodothyronine, thyroid, guidelines, treatment, deiodinases, clinical symptoms, quality of life, cognition, mood, depression, body weight, heart rate, cholesterol, bone markers, SHBG, and patient preference for combined therapy. The search was restricted to reports published in English since 1970, but some reports published before 1970 were also incorporated. We supplemented the search with records from personal files and references of relevant articles and textbooks. Parameters analyzed included the rationale for combination treatment, the type of patients to be selected, the optimal T(4)/T(3) ratio, and the potential benefits of this therapy on symptoms of hypothyroidism, quality of life, mood, cognition, and peripheral parameters of thyroid hormone action.

EVIDENCE SYNTHESIS

The outcome of our analysis suggests that it may be time to consider a personalized regimen of thyroid hormone replacement therapy in hypothyroid patients.

CONCLUSIONS

Further prospective randomized controlled studies are needed to clarify this important issue. Innovative formulations of the thyroid hormones will be required to mimic a more perfect thyroid hormone replacement therapy than is currently available.

Recombinant human thyrotropin in veterinary medicine: current use and future perspectives

Recombinant human thyrotropin (rhTSH) was developed after bovine thyrotropin (bTSH) was no longer commercially available. It was approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMEA) as an aid to diagnostic follow-up of differentiated thyroid carcinoma in humans and for thyroid remnant ablation with radioiodine. In addition, rhTSH is used in human medicine to evaluate thyroid reserve capacity and to enhance radioiodine uptake in patients with metastatic thyroid cancer and multinodular goiter. Likewise, rhTSH has been used in veterinary medicine over the last decade. The most important veterinary use of rhTSH is thyroidal functional reserve testing for the diagnosis of canine hypothyroidism. Recent pilot studies performed at Ghent University in Belgium have investigated the use of rhTSH to optimize radioiodine treatment of canine thyroid carcinoma and feline hyperthyroidism. Radioiodine treatment optimization may allow a decreased therapeutic dosage of radioiodine and thus may improve radioprotection. This review outlines the current uses of rhTSH in human and veterinary medicine, emphasizing research performed in dogs and cats, as well as potential future applications.

Long-term treatment with supraphysiological doses of thyroid hormone in affective disorders - effects on bone mineral density

BACKGROUND

To investigate the long-term effects of supraphysiological, TSH suppressive doses of levothyroxine (TSDL) on bone mineral density (BMD) in patients with affective disorders during an average treatment duration of 69 months.

METHODS

In 22 patients, BMD of the spine (lumbar vertebrae L1-4) and femur (femoral neck) was measured by dual energy X-ray absorptiometry (DXA). Forty (40) measurements from the prior study and 48 new follow-up measurements were included. BMD was expressed as Z-scores as a population standard reference. We used a linear mixed model to investigate the duration of TSDL as an explanatory factor for change in BMD compared to an age and gender matched reference population.

RESULTS

We found no significant differences in bone loss between the study and the reference population. The estimated non-significant decrease in Z-score compared to the reference population found was: a) lumbar spine (L1-4): -0.00069/month (p=0.9759) b) neck region of femur: -0.01405/month (p=0.4436). We did not find the factors age, thyroxine-dose or postmenopausal state as predictors for a decline in BMD.

LIMITATIONS

Small sample size, no bone density assessment prior to treatment with TSDL, no patient control group with mood disorders who did not receive TSDL, variable bone density follow-up intervals.

CONCLUSION

This study did not demonstrate evidence that long-term treatment of affectively ill patients with TSDL accelerates loss of BMD compared to an age- and gender-matched reference population.

[Levothyroxine and the problem of interchangeability of drugs with narrow therapeutic index]

The exchange of a prescribed drug by other similar, by generic products and even by custom products has become common practice in our country, often ignoring basic tenets of bioequivalence, interchangeability, stability and characteristics of the pharmaceutical compounds. In the case of drugs of narrow therapeutic index, such as levothyroxine, these problems are intensified, putting the effectiveness of treatment and patient health at serious risk. We review the pertinent legislation, emphasizing the characteristics of levothyroxine and adverse effects that limit the interchangeability of the compound.