Acute changes in clinical parameters and thyroid function peripheral markers following L-T4 withdrawal in patients totally thyroidectomized for thyroid cancer

Transiently impaired endothelial function during thyroid hormone withdrawal in differentiated thyroid cancer patients

Purpose

Endothelial dysfunction, which was associated with chronic hypothyroidism, was an early event in atherosclerosis. Whether short-term hypothyroidism following thyroxine withdrawal during radioiodine (RAI) therapy was associated with endothelial dysfunction in patients with differentiated thyroid cancer (DTC) was unclear. Aim of the study was to assess whether short-term hypothyroidism could impair endothelial function and the accompanied metabolic changes in the whole process of RAI therapy.

Methods

We recruited fifty-one patients who underwent total thyroidectomy surgery and would accept RAI therapy for DTC. We analyzed thyroid function, endothelial function and serum lipids levels of the patients at three time points: the day before thyroxine withdrawal(P₁), the day before ¹³¹I administration(P₂) and 4-6 weeks after RAI therapy(P₃). A high-resolution ultrasound named flow-mediated dilation (FMD) was used to measure endothelial function of the patients.

Results

We analyzed the changes of FMD, thyroid function and lipids at three time points. FMD(P₂) decreased significantly compared to FMD(P₁) (P₁vsP₂, 8.05 ± 1.55vs 7.26 ± 1.50, p<0.001). There was no significant difference between FMD(P₃) and FMD(P₁) after restoring TSH (thyroid stimulating hormone) suppression therapy (P₁ vs P3, 8.05 ± 1.55 vs 7.79 ± 1.38, p=0.146). Among all parameters, the change of low-density lipoprotein (ΔLDL) was the only factor correlated negatively with the change of FMD (ΔFMD) throughout the RAI therapy process (P_1-2, r=-0.326, p=0.020; P_2-3, r=-0.306, p=0.029).

Conclusion

Endothelial function was transiently impaired in DTC patients at short-term hypothyroidism state during the RAI therapy, and immediately returned to the initial state after restoring TSH suppression therapy.

Dyslipidemia Risk in Thyroid Cancer Patients: A Nationwide Population-Based Cohort Study

OBJECTIVE

Thyroid cancer (TC) prevalence has been rapidly increasing. While the relationship between thyroid hormones and lipids has been widely investigated, studies regarding dyslipidemia in patients with TC have been scarce and controversial. We aimed to investigate dyslipidemia risk after TC diagnosis compared to the general population without TC.

METHOD

A population-based prospective study was conducted using data from the Korean National Health Insurance Service-National Sample Cohort Database 2.0 (NHIS-NSC DB 2.0), with health insurance claim data of 1,108,369 subjects between 2002 and 2015. The final study sample comprised 466,735 adult subjects without TC or dyslipidemia diagnoses before the index year, 2009. Bidirectional analyses were performed using prospective and retrospective concepts. In the prospective analysis, Kaplan-Meier estimates were calculated and log-rank tests and univariable and multivariable Cox regression analyses were performed to determine the relationship between TC and dyslipidemia. The retrospective analysis involved 1:5 nested case-control matching based on dyslipidemia status and conditional logistic regression analysis.

RESULTS

No significant difference in dyslipidemia incidence was observed between TC patients and the control group, in either the prospective matched (log-rank P = 0.483) or non-matched (log-rank P = 0.424) analyses, or the retrospective analysis (P = 0.3724). In the prospective analysis, 193 patients after TC diagnosis showed similar risk of developing dyslipidemia with the 466,542 controls during the median 7 years of follow-up (unadjusted hazard ratio [HR], 1.102; 95% confidence interval [CI], 0.878-1.383; adjusted HR, 0.932; 95% CI, 0.707-1.230). Multiple propensity score-adjusted models showed similar results, and 114 patients and 570 matched controls showed an HR of 0.818 (95% CI, 0.598-1.120). In the retrospective comparison of dyslipidemia risk in 170 patients and 277,864 controls, the odds ratio was 0.822 (95% CI, 0.534-1.266).

CONCLUSIONS

Dyslipidemia risk was not significantly different between patients with TC and the general population, in both prospective and retrospective analyses.

Biochemical bone turnover markers in hormonal disorders in adults: a narrative review

BACKGROUND

Hormonal disorders are often associated with abnormal levels of bone turnover markers (BTMs). N-terminal propeptide of type I procollagen (PINP) and serum C-terminal cross-linking telopeptide of type I collagen (CTX-I) are the reference markers of bone formation and bone resorption, respectively.

METHODS

A comprehensive literature search within the MEDLINE and Web of Science databases was performed.

RESULTS

Acromegaly is associated with higher BTM levels, which decrease during the remission after treatment. Adult-onset growth hormone deficiency is often associated with decreased BTM levels. Growth hormone replacement therapy stimulates bone turnover and increases BTM levels. Hypothyroidism is characterized by general slowing of bone metabolism which is reflected by lower BTM levels. The replacement thyroid hormone therapy increases the bone turnover rate and BTM levels increase. Patients with thyroid cancer receive a suppressive dose of thyroid hormones and may have slightly elevated BTM levels. Patients with overt hyperthyroidism had higher BTM levels and anti-thyroid therapy induces a rapid decrease in the BTM levels. Patients with overt primary hyperparathyroidism have higher BTM levels, whereas those with asymptomatic and normocalcemic hyperparathyroidism usually have normal BTM levels. Hypoparathyroidism is characterized by slightly decreased BTM levels. Cushing's syndrome is characterized consistently by markedly decreased osteocalcin concentration, whereas data on other BTMs are discordant.

CONCLUSIONS

BTMs help us to better understand mechanisms of the impact of hormonal disorders and their treatment on bone metabolism. However, it is unknown whether BTMs may be used to monitor the effect of their treatments on bone in the clinical practice.

Gender impact on the correlation between thyroid function and serum lipids in patients with differentiated thyroid cancer

The present study aimed to explore the association between thyroid stimulating hormone (TSH) and serum lipids in patients with differentiated thyroid cancer (DTC), with a focus on the risk of hyperlipidemia between different genders. The study included 352 DTC patients who were ready to receive I-131 therapy as well as 352 matched normal controls. In the DTC group, 157 patients were monitored for TSH and lipid parameters prior to and after 1 month of thyroxine therapy. Results were analyzed using t-tests, Pearson bivariate correlation and binary logistic regression analyses. All participants were divided into 3 subgroups according to TSH levels: Subgroup 1 (normal TSH level), subgroup 2 (TSH between 5 and 30 µIU/ml), and subgroup 3 (TSH >30 µIU/ml). Serum total cholesterol (TC), triglycerides (TG), and low-density lipoprotein-cholesterol (LDL-C) levels were significantly higher in the DTC group than in the control group. The levels of these parameters decreased after thyroxine therapy and significant positive correlations were observed between TSH and TC, and TG and LDL-C in both genders. Binary logistic regression demonstrated that female DTC patients had higher risks of developing hyperlipidemia than male patients, and these risks increased when TSH increased. For example, the odds ratios (ORs) of high TC in subgroup 2 were 3.30 in males and 4.60 in females, respectively. However, in subgroup 3, the ORs were 9.40 in males and 13.12 in females, respectively. The results of the present study showed that after thyroidectomy, the risk of dyslipidemia markedly increased in DTC patients. More importantly, female patients had a higher risk than male patients.

Diminished Quality of Life and Increased Brain Functional Connectivity in Patients with Hypothyroidism After Total Thyroidectomy

BACKGROUND

Acute hypothyroidism induced by thyroid hormone withdrawal (THW) in patients with thyroid cancer after total thyroidectomy can affect mood and quality of life (QoL). While loss or dysregulation of thyroid hormone (TH) has these well-known behavioral consequences, the effects of TH alterations on brain function are not well understood. Resting state functional connectivity (FC) measured by functional magnetic resonance imaging (fMRI) allows non-invasive evaluation of human brain function. This study therefore examined whether THW affects resting state FC and whether changes in FC correlate with the mood or QoL of the patients with THW status.

METHODS

Twenty-one patients who had undergone total thyroidectomy for thyroid cancer were recruited. Resting state fMRI scanning of the brain, thyroid function tests, and administration of the 12-Item Short Form Health Survey (SF-12) and the Patient Health Questionnaire-9 (PHQ-9) were performed before and after two weeks of THW. Regional homogeneity (ReHo), one of the measures of resting state FC, was calculated, and each voxel was compared between before and after THW in 19 patients. The ReHo values were extracted from the regions of interest showing within-group differences in ReHo values after THW, and correlations of ReHo values with thyrotropin (TSH) levels, total score of the PHQ-9, and composite scores of the SF-12 were statistically evaluated.

RESULTS

Higher ReHo was observed after THW in the brain cortical regions across primary motor and sensory, visual, and association cortices. Among the regions, the ReHo values in the bilateral pre- and postcentral gyri, bilateral middle occipito-temporal cortices, the left precuneus, and the left lingual gyrus showed positive correlations with serum TSH levels after THW. Higher ReHo values in the bilateral pre- and postcentral gyri, the left middle temporo-occipital cortices, and the left ligual gyrus correlated with the lower mental component summary score from the SF-12, while higher ReHo values in the bilateral pre- and postcentral gyri correlated with higher total scores in the PHQ-9.

CONCLUSIONS

Local brain FC is increased in the acute hypothyroid state. Higher FC correlates with a poorer mental QoL and increased depression in the hypothyroid state.

Comparison of conventional L-thyroxine withdrawal and moderate hypothyroidism in preparation for whole-body 131-I scan and thyroglobulin testing

PURPOSE

After thyroidectomy for thyroid cancer, patients often withdraw L-T4 for diagnostic or therapeutic purposes, showing signs and symptoms of hypothyroidism. A slighter hypothyroidism (reducing L-T4 to one-half) has been proposed to limit these inconveniences. We evaluated half-dose L-T4 protocol, in comparison to conventional L-T4 withdrawal, in terms of effectiveness and improvement of clinical and biochemical disorders.

METHODS

We randomized 55 thyroid cancer patients into two groups: 29 patients underwent 5 weeks of half-dose of previous L-T4 treatment (HD group); 26 patients replaced L-T4 with L-T3 for 3 weeks followed by 2 weeks of withdrawal (TW group). Clinical features (Zulewsky clinical score) and biochemical parameters (lipids, liver, and muscle enzymes) were evaluated in all patients at baseline and after 5 weeks.

RESULTS

Total cholesterol, creatine kinase, lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase increased at 5 weeks in both groups, but significantly more in TW, but no difference was found by clinical score. Patients who achieved the thyroid-stimulating hormone (TSH) target value (25 µU/ml) were 92.3% in TW group and 48.3% in HD group (p < 0.001). In the HD group, only basal TSH statistically correlated with the achievement of the TSH target. Receiver operating characteristic curves indicated that a basal TSH ≥0.52 μU/ml is required to reach an adequate TSH level.

CONCLUSIONS

Half-dose L-T4 protocol, compared to conventional L-T4 withdrawal, is associated with less biochemical disorders but no significant clinical advantage. Therefore, the half-dose protocol reaches an adequate TSH target in 48.3% of patients and is not effective unless basal serum TSH is ≥0.52 μU/ml.

Weight Changes in Patients with Differentiated Thyroid Carcinoma during Postoperative Long-Term Follow-up under Thyroid Stimulating Hormone Suppression

BACKGROUND

There are limited data about whether patients who receive initial treatment for differentiated thyroid cancer (DTC) gain or lose weight during long-term follow-up under thyroid stimulating hormone (TSH) suppression. This study was aimed to evaluate whether DTC patients under TSH suppression experience long-term weight gain after initial treatment. We also examined the impact of the radioactive iodine ablation therapy (RAIT) preparation method on changes of weight, comparing thyroid hormone withdrawal (THW) and recombinant human TSH (rhTSH).

METHODS

We retrospectively reviewed 700 DTC patients who underwent a total thyroidectomy followed by either RAIT and levothyroxine (T4) replacement or T4 replacement alone. The control group included 350 age-matched patients with benign thyroid nodules followed during same period. Anthropometric data were measured at baseline, 1 to 2 years, and 3 to 4 years after thyroidectomy. Comparisons were made between weight and body mass index (BMI) at baseline and follow-up.

RESULTS

Significant gains in weight and BMI were observed 3 to 4 years after initial treatment for female DTC but not in male patients. These gains among female DTC patients were also significant compared to age-matched control. Women in the THW group gained a significant amount of weight and BMI compared to baseline, while there was no increase in weight or BMI in the rhTSH group. There were no changes in weight and BMI in men according to RAIT preparation methods.

CONCLUSION

Female DTC patients showed significant gains in weight and BMI during long-term follow-up after initial treatment. These changes were seen only in patients who underwent THW for RAIT.

Body Mass Index Is Associated with Hypercholesterolemia following Thyroid Hormone Withdrawal in Thyroidectomized Patients

Thyroid hormone withdrawal (THW) for postoperative radioiodine adjuvant therapy or diagnostic radioiodine whole body scan in patients with differentiated thyroid cancers results in acute thyroid hormone deficiency and abnormal lipid profiles. To better clarify the clinical pattern of dyslipidemia occurring after THW, we retrospectively analyzed the association between serum total cholesterol level after THW and various clinical factors in a total of 61 patients who underwent total thyroidectomy due to papillary thyroid cancers from January 2010 to March 2012, in Severance Hospital, Seoul, Korea. Preoperative baseline total cholesterol was significantly correlated with post-THW total cholesterol level; however, age, gender, or elevated TSH level after THW itself was not correlated with post-THW total cholesterol level. A significant correlation between preoperative measured BMI and post-THW total cholesterol level was found (r = 0.263, P = 0.041). In multiple logistic analysis, BMI was an independent determining factor of post-THW total cholesterol level (P = 0.012).

Radioiodine therapy in benign thyroid diseases: effects, side effects, and factors affecting therapeutic outcome

Radioiodine ((131)I) therapy of benign thyroid diseases was introduced 70 yr ago, and the patients treated since then are probably numbered in the millions. Fifty to 90% of hyperthyroid patients are cured within 1 yr after (131)I therapy. With longer follow-up, permanent hypothyroidism seems inevitable in Graves' disease, whereas this risk is much lower when treating toxic nodular goiter. The side effect causing most concern is the potential induction of ophthalmopathy in predisposed individuals. The response to (131)I therapy is to some extent related to the radiation dose. However, calculation of an exact thyroid dose is error-prone due to imprecise measurement of the (131)I biokinetics, and the importance of internal dosimetric factors, such as the thyroid follicle size, is probably underestimated. Besides these obstacles, several potential confounders interfere with the efficacy of (131)I therapy, and they may even interact mutually and counteract each other. Numerous studies have evaluated the effect of (131)I therapy, but results have been conflicting due to differences in design, sample size, patient selection, and dose calculation. It seems clear that no single factor reliably predicts the outcome from (131)I therapy. The individual radiosensitivity, still poorly defined and impossible to quantify, may be a major determinant of the outcome from (131)I therapy. Above all, the impact of (131)I therapy relies on the iodine-concentrating ability of the thyroid gland. The thyroid (131)I uptake (or retention) can be stimulated in several ways, including dietary iodine restriction and use of lithium. In particular, recombinant human thyrotropin has gained interest because this compound significantly amplifies the effect of (131)I therapy in patients with nontoxic nodular goiter.

Growth hormone treatment in children with idiopathic short stature: correlation of growth response with peripheral thyroid hormone action

OBJECTIVE

Idiopathic short stature (ISS) describes short children with normal GH secretion. Although GH treatment increases their heights, growth response to the therapy differs among patients. Thyroid hormones (TH) are essential for longitudinal growth acting mainly through TH receptors (TR) α and β. We have previously reported that GH treatment reduced peripheral TH action in Turner Syndrome by TR down-regulation. The aims of the study were to assess the effect of GH treatment to ISS on peripheral TH action and the correlation between thyroid status and growth response to the therapy. SUBJECTS, DESIGN AND MEASUREMENTS: Eighteen normal (control) and twenty-five ISS children were enrolled and evaluated before and after 12 months of life time (control) or 12 months of GH therapy (ISS). Fasting blood was used for serum biochemical evaluations, peripheral blood mononuclear cells for TR mRNA determination by QRT-PCR and growth parameters by standard methods.

RESULTS

GH treatment modified neither TR mRNA levels nor serum markers of TH action in ISS evaluated as a whole group. However, the individual change in TRβ mRNA levels correlated to the change in sex hormone-binding globulin (SHBG) levels after GH therapy. The growth response to GH correlated positively with the change in TRα mRNA level and negatively with that in TRβ mRNA, TSH and SHBG levels. The change in each TR mRNA isoform after GH treatment correlated negatively with its own basal level.

CONCLUSIONS

GH therapy induced individual changes in TR expression in ISS that correlated with their growth response. The basal TR mRNA level could predetermine the change in TR expression and therefore the sensitivity to GH treatment.

Endothelial function is not changed during short-term withdrawal of thyroxine in patients with differentiated thyroid cancer and low cardiovascular risk

PURPOSE

The incidence of differentiated thyroid cancer is increasing in young adults and females in Korea. Some of them experience short-term hypothyroidism in preparation for radioiodine (RAI) therapy, which can have a deleterious effect on the cardiovascular system. However, it is not clear if short-term hypothyroidism induces endothelial dysfunction in patients with low cardiovascular risk. Therefore, the aim of this study was to investigate whether short-term hypothyroidism is associated with endothelial dysfunction in patients with low cardiovascular risk.

MATERIALS AND METHODS

To evaluate the effect of short-term hypothyroidism on endothelial function in this group, we recruited fifteen female patients with low cardiovascular risk. We analyzed clinical, biochemical, and cardiovascular parameters at four time points: the last day on levothyroxine (LT4) at their usual thyroid-stimulating hormone (TSH)-suppressive doses (P1), 7 days (P2) and 4 weeks (P3) after withdrawal of LT4, and 8 weeks (P4) after replacement of the previous dose of LT4. A high resolution ultrasound was used to measure brachial artery diameter at rest, after reactive hyperemia, and after sublingual nitroglycerin.

RESULTS

During short-term hypothyroidism (P3), serum concentrations of total cholesterol and low-density lipoprotein (LDL)-cholesterol were increased (p < 0.001 for each period). In spite of having worsened lipid states, serum high sensitivity C-reactive protein or flow-mediated vasodilatation, which is one of the surrogate markers of the endothelial function, did not change during short-term hypothyroidism.

CONCLUSION

Short-term hypothyroidism induced worsening of metabolic parameters, but not enough to induce the endothelial dysfunction in patients with low cardiovascular risk.

Metabolic and cardiovascular risk in patients with a history of differentiated thyroid carcinoma: A case-controlled cohort study

Hyperthyroidism seems to increase metabolic and cardiovascular risk, while the effects of sub-clinical hyperthyroidism are controversial. We evaluated metabolic and cardiovascular parameters in differentiated thyroid carcinoma (DTC) patients with suppressed thyrotropin (TSH) due to levo-thyroxine (L-T4) therapy. We studied DTC patients and, as a control group, patients with a history of surgery for non-malignant thyroid pathology. Significantly higher insulin and lower HDL-cholesterol levels were recorded in DTC subjects. In both groups, insulin levels were significantly related with body mass index (BMI) but not with age or L-T4 dosage. In DTC patients, a significant negative correlation was seen between HDL-cholesterol and BMI or L-T4 dosage. In both groups, intima-media thickness (IMT) correlated positively with age, BMI, glucose levels and systolic blood pressure. In DTC patients, increased IMT was significantly correlated with glycated hemoglobin (HbA1c), cholesterol and triglycerides. In DTC patients, C-reactive protein correlated positively with insulin, insulin resistance, triglycerides and systolic blood pressure, and negatively with HDL-cholesterol. In both DTC and control subjects, fibrinogen correlated positively with age, BMI, increased IMT, HbA1c and systolic blood pressure. In DTC subjects, plasma fibrinogen concentrations correlated positively with insulin resistance, cholesterol and LDL-cholesterol, and negatively with TSH levels. Our data confirm that the favorable evolution of DTC can be impaired by a high incidence of abnormal metabolic and cardiovascular data that are, at least in part, related to L-T4 therapy. These findings underline the need for adequate L-T4 titration.

Growth hormone (GH) treatment reduces peripheral thyroid hormone action in girls with Turner syndrome

OBJECTIVE

Turner syndrome (TS) is an indication for GH therapy in spite of the modest growth response. Somatic growth depends not only on GH insulin-like growth factor I (IGF-I) axis but also on thyroid hormone (TH) status. We have previously reported that supraphysiological IGF-I levels diminished TH actions in rat tissues by reducing the nuclear TH receptor (TR). GH treatment to TS patients induces high IGF-I levels and therefore a reduction of TH action in tissues may be expected. We aimed at evaluating the effect of GH therapy in TS girls on peripheral TH action.

DESIGN AND PATIENTS

We set up a reverse transcription-polymerase chain reaction (RT-PCR) for TR mRNA estimation in peripheral blood mononuclear cells (PBMC) and compared TR mRNA levels from 10 normal, 10 TS and 10 TS girls under GH therapy (0.33 mg/kg/week for 0.5-2 years).

MEASUREMENTS

After RNA extraction from PBMC, TR and beta-actin mRNAs were coamplified by RT-PCR. In addition serum biochemical markers of TH action were measured: thyrotropin (TSH), sex hormone binding globulin (SHBG), osteocalcin (OC), beta-crosslaps (beta-CL), iodothyronines by electrochemiluminescency and IGF-I by immunoradiometric assay (IRMA) with extraction.

RESULTS

TR mRNAs from PBMC were reduced in TS patients under GH treatment. In turn, serum TSH, OC, beta-CL and IGF-I were increased while SHBG was reduced by GH treatment in TS patients.

CONCLUSIONS

GH treatment reduced TR expression in PBMC and biochemical serum markers of TH action. These results suggest that GH treatment in TS patients impair peripheral TH action at tissue level and prompt a role in the reduced growth response to the therapy.

Serum osteoprotegerin and soluble receptor activator of nuclear factor kappaB ligand levels in patients with a history of differentiated thyroid carcinoma: a case-controlled cohort study

Overt hyperthyroidism is associated with changes in bone metabolism, whereas the effect of levothyroxine (L-T4) load in patients with differentiated thyroid carcinoma (DTC) is controversial. The aim of our study was to evaluate osteoprotegerin (OPG) and soluble receptor activator of nuclear factor kappaB ligand (RANK-L) in patients with DTC with suppressed endogenous thyrotropin due to L-T4 regimen. A cohort of 80 subjects with DTC (68 women and 12 men; age range, 27-81 years) was studied. A cohort of 55 subjects with a history of partial or total surgery for nonmalignant thyroid pathology served as a control group. Groups were matched for sex, age, and body mass index. Per-week dosage of L-T4 was significantly higher in patients with DTC than in controls (P < .001). More elevated free T(4) concentrations (P < .001) and more suppressed thyrotropin and thyroglobulin levels (P < .001) were found in subjects with DTC than in controls. No difference in serum or urinary parameters related to bone metabolism or dual-energy x-ray absorptiometry was noted between the groups. Overall, OPG levels were similar in both groups but were significantly (P = .03) lower in postmenopausal women with DTC than in postmenopausal control women. Only control women showed lower OPG levels in premenopausal than in postmenopausal (P = .002) conditions. Overall, RANK-L levels were significantly higher (P = .03) in subjects with DTC than in controls. In both groups, OPG and RANK-L levels were unrelated to each other. A significant positive correlation was seen between OPG levels and age in both subjects with DTC (P < .001) and controls (P < .001). Serum RANK-L correlated negatively with age in subjects with DTC (P = .05). Although there were several differences in L-T4 dosages, OPG and RANK-L levels were similar in patients with a history of DTC and those with a history of nonmalignant thyroid diseases. The correlation between circulating OPG and RANK-L levels was not significant. The increase in OPG with age indicates its protective role in bone loss. The cause of bone loss after long-term L-T4 load will be more extensively studied.

Effects of either LT4 monotherapy or LT4/LT3 combined therapy in patients totally thyroidectomized for thyroid cancer

After total thyroidectomy all thyroid cancer patients require lifelong treatment with thyroid hormones; the treatment of choice is synthetic levothyroxine (LT4). The question of whether these patients might benefit from the combined LT4 and liothyronine (LT3) treatment has been addressed with conflicting conclusions. The aim of the present study was to compare the effects of combined low LT4/LT3 molar ratio therapy versus LT4 monotherapy on various target organs and tissues in patients thyroidectomized for thyroid cancer. Urine collection (24 hour), a fasting blood sample for laboratory examinations, thyroid function clinical score, and cardiovascular, neurological, and neuropsychological evaluations were obtained. Clinical parameters and peripheral markers of thyroid function were measured during the two different treatment regimens in 20 patients. Mean serum aspartate aminotransferase, alanine aminotransferase, sex hormone binding globulin, and osteocalcin values were significantly higher during the combined treatment. No significant differences in the clinical score, the systolic and diastolic performance, and the neurological and neuropsychological evaluations were observed between the two treatment regimens. Moreover, no alteration due to subclinical hyperthyroidism or to the fluctuations in serum T3 concentrations during the combined therapy was observed. In conclusion, we found no evidence that combined therapy with a low LT4/LT3 molar ratio resulted in improved well-being and cognitive function or in increased thyroid hormone action on peripheral tissues in respect to LT4 monotherapy. Until future large, blind, randomized, and controlled trials prove otherwise, LT4 should remain the standard treatment for thyroid cancer patients.