Thyroid function related symptoms during levothyroxine monotherapy in athyreotic patients

Adult Thyroid Outcomes of Congenital Hypothyroidism

BACKGROUND

More than 40 years have passed since the introduction of newborn screening for congenital hypothyroidism (CH), and many early diagnosed patients have reached adulthood. Their thyroid morphology and function have been little studied. This cross-sectional, observational study was conducted to characterize the thyroid morphology and function of adult CH patients diagnosed in the framework of newborn screening for CH.

METHODS

A total of 103 adult CH patients born after 1979 were enrolled at Ito Hospital, Tokyo, Japan, and were classified into Goiter, Normal gland, and Dysgenesis groups based on ultrasonographic findings. For 60 patients, genetic analysis was performed. Thyroid function test results and the proportion of patients with thyroid nodules were compared among the three groups and between 56 female CH patients and 168 non-CH women matched for TSH levels.

RESULTS

A significantly low serum free T3/free T4 ratio (0.22) was observed in the Dysgenesis group. Thyroid nodules were detected in 14.3% (8/56) of female CH patients, more frequently than in non-CH women. Thyroid nodules were detected the most frequently in the Goiter group (71%, 10/14). Genetic defects were identified in 89% (8/9) of patients belonging to the Goiter group, including thyroglobulin defect (33%, 3/9), thyroid peroxidase defect (33%, 3/9), and dual oxidase 2 defect (22%, 2/9).

CONCLUSIONS

Our results suggest that adults with thyroid dysgenesis on levothyroxine replacement therapy have relative T3 deficiency. Most adults with goitrous CH have genetic dyshormonogenesis. They are at high risk of developing thyroid nodules. Our findings support the current guideline recommendation that CH patients with dyshormonogenesis should undergo periodic thyroid ultrasonography.

Restoration of euthyroidism with levothyroxine: implications of etiology of hypothyroidism and the degree of residual endogenous thyroid function

There are many thyroid-related factors that combine with non-thyroid-related factors in order to affect the patient response to treatment of hypothyroidism, in terms of their satisfaction with therapy. Some of the thyroid-derived factors include the etiology of the hypothyroidism and the amount of residual thyroid function that the patient retains. These two factors may be intertwined and affected by a third influence, the presence of thyroid peroxidase antibodies. The downstream consequences of the interactions between these three factors may influence both free thyroxine and free triiodothyronine levels, TSH concentrations, and various thyroid biomarkers. Evidence of the widespread importance of thyroid hormones can be inferred from the multiple genes that are regulated, with their regulation affecting multiple serum biomarkers. Thyroid biomarkers may extend from various well-known serum markers such as lipids and sex hormone-binding globulin to serum levels of thyroid hormone metabolites. Moreover, the interplay between thyroid hormones and biomarkers and their relative ratios may be different depending on the hypothyroidism etiology and degree of residual thyroid function. The ultimate significance of these relationships and their effect on determining patient-reported outcomes, quality of life, and patient satisfaction is, as yet, poorly understood. However, identification of better biomarkers of thyroid function would advance the field. These biomarkers could be studied and correlated with patient-reported outcomes in future prospective studies comparing the impact of various thyroid hormone therapies.

Proportion of serum thyroid hormone concentrations within the reference ranges in athyreotic patients on levothyroxine monotherapy: a retrospective study

Background

In patients receiving thyroid-stimulating hormone (TSH) suppressive therapy with levothyroxine (LT₄) after total thyroidectomy for thyroid cancer, thyroid function tests should be performed to adjust the LT₄ dose. Specifically, serum TSH concentrations are commonly measured because TSH suppression is necessary according to thyroid cancer risk. The aim of the present study was to elucidate whether free thyroxine (FT₄) or free triiodothyronine (FT₃) indicates better for adjusting the dose in athyreotic patients on LT₄ monotherapy after total thyroidectomy.

Methods

We retrospectively studied the compatibility of free thyroid hormone (FT₄ and FT₃) concentrations with reference ranges in athyreotic patients on LT₄ monotherapy after total thyroidectomy.

Results

We identified 2210 consecutive patients from their medical records. Of these patients, 250 had both FT₄ and FT₃ concentrations in addition to TSH. Two hundred seven had serum TSH concentrations below the reference range (0.5–5.0 μIU/mL), while 43 had them within the reference range. In the 207 patients with TSH concentrations below the reference range, 61 patients (29.5%) had FT₄ concentrations within the reference range (0.9–1.7 ng/dL) and 146 patients (70.5%) had FT₄ concentrations above the reference range. In contrast, 10 patients (4.8%) had FT₃ concentrations below the reference range (2.3–4.0 pg/mL) and 8 (3.9%) had FT₃ concentrations above the reference range; 189 patients (91.3%) had concentrations within the reference range. Of the 43 patients with TSH concentrations within the reference range, 25 (58.1%) had FT₄ concentrations within the reference range and 18 (41.9%) had FT₄ concentrations above the reference range. While, 11 patients (25.6%) had FT₃ concentrations below the reference range and one (2.3%) had FT₃ concentrations above the reference range; hence, 31 patients (72.1%) had FT₃ concentrations within the reference range.

Conclusion

This study showed that measuring FT₃ concentrations rather than FT₄ concentrations as the subsequent parameter of thyroid function might be more useful for disease management in terms of the proportion of serum thyroid hormone concentrations within the reference ranges. Furthermore, FT₃ measurement could be useful in providing more detailed treatments, including avoiding more aggressive TSH suppressive therapy and identifying the presence of low T₃ syndrome in the background.

The magnitude of increased Levothyroxine dose during pregnancy in patients on thyroid-stimulating hormone (TSH) suppression treatment after total thyroidectomy for papillary carcinoma

The dose of L-T₄ replacement for hypothyroidism often needs to be increased after pregnancy. In our institution, patients are instructed to double the dose 2 days a week after pregnancy. However, there is scarce evidence supporting the need for a dose increase after pregnancy in patients with preconception thyroid-stimulating hormone (TSH) suppression (TSH <0.3 μIU/mL). This study aimed to determine the need for a dose increase in L-T₄ among women with a TSH-suppressive dose of L-T₄ before pregnancy. In this retrospective observational study, between January 2008 and December 2018, we analyzed 166 pregnancies in 134 patients on TSH suppression treatment after total thyroidectomy for papillary carcinoma. Thyroid function tests were performed before and in the first trimester of pregnancy. The dose was adjusted and maintained during the first trimester of pregnancy in 76 pregnancies (group A) and 90 pregnancies (group B), respectively. The median serum TSH level was significantly lower in group A than that in group B (0.014 μIU/mL (IQR, 0.005-0.071) vs. 0.155 μIU/mL (IQR, 0.021-0.657), p < 0.001). TSH suppression could not be maintained after pregnancy in 15.8% and 38.9% of the pregnancies in groups A and B, respectively. Increasing the post-pregnancy dose by an average of 27.4% resulted in maintenance of TSH suppression after pregnancy in 84.2% of pregnancies. In conclusion, this study suggests that increasing the L-T₄ dose after pregnancy may be appropriate in postoperative thyroid cancer patients whose serum TSH levels should be suppressed.

Fatigue and quality of life among thyroid cancer survivors without persistent or recurrent disease

BACKGROUND

Cancer-related fatigue is one of the most important issues for patients, but research on this topic is sparse. This study aimed to determine the prevalence of fatigue in postoperative patients with papillary thyroid carcinoma (PTC) and to identify the clinical features associated with fatigue.

METHODS

We conducted a cross-sectional study on 292 thyroid cancer survivors. Fatigue and quality of life were the study outcomes, measured using the Cancer Fatigue Scale (CFS) and the SF-36 version 2.0. Furthermore, correlations of demographic characteristics and hormonal data with the CFS scores were assessed by univariable and multivariable analyses.

RESULTS

The prevalence of fatigue was 41.8% (95% CI: 36.1, 47.5). The CFS score was significantly correlated with the free T3 level (Pearson's r = -0.123, 95% CI: -0.234, -0.008). Multiple regression analysis revealed that the free T3 level and having a job were significant predictors of the CFS score, with unstandardized regression coefficients of -2.52 (95% CI: -4.94, -0.09) and 2.85 (95% CI: 0.49, 5.20), respectively. The median Z-scores were negative for General Health (-0.28) and Vitality (-0.15) subscales of the SF-36. The CFS score was a significant predictor of summary scores of the SF-36. The free T3 level was significantly associated with the physical component summary score with an unstandardized coefficient of 3.20 (95% CI: 0.77, 5.63).

CONCLUSIONS

Fatigue was prevalent and associated with poor quality of life among PTC survivors. Thyroid functional status, particularly the level of free T3, may be worth to be considered in alleviating the burden.

Association between serum thyroid hormone balance and thyroid volume in patients treated with levothyroxine monotherapy for hypothyroidism

Many previous studies including ours have reported that athyreotic patients on levothyroxine (LT₄) have relatively low serum free triiodothyronine (FT₃) levels, whereas patients with large goitrous diseases often have high serum FT₃ levels. Here we investigated Hashimoto thyroiditis (HT) patients on LT₄ to study the relationship between thyroid volume (TV) and thyroid hormone status in hypothyroid patients on LT₄. We retrospectively studied 408 euthyroid HT patients treated with LT₄ for hypothyroidism; divided them as per TV and compared serum levels of free thyroxine (FT₄) and FT₃ and the FT₃/FT₄ ratio in each patient group with those in euthyroid matched control group. We also evaluated the association between serum FT₃ level and FT₃/FT₄ ratio and TV among HT patients on LT₄. In patients with TV <15 mL, serum FT₃ levels were significantly lower than those in controls. In patients with TV 15-80 mL, serum FT₃ levels were equivalent to those in controls. In patients with TV ≥80 mL, the serum FT₃ levels were significantly higher than those in controls. The serum FT₃ level (r = 0.35, p < 0.01) and FT₃/FT₄ ratio (r = 0.42, p < 0.01) showed a positive correlation with TV. TVs in HT patients on LT₄ caused differences in serum thyroid hormone balance, as increasing volume increases the serum FT₃ level and FT₃/FT₄ ratio. Serum thyroid hormone balance in HT patients with smaller thyroids was similar to that in athyreotic patients. Mild thyrotropin suppression with LT₄ is needed to achieve normal FT₃ levels in such patients.

Levothyroxine Therapy in Thyrodectomized Patients

Administration of the optimal dose of levothyroxine (LT4) is crucial to restore euthyroidism after total thyroidectomy. An insufficient or excessive dosage may result in hypothyroidism or thyrotoxicosis, either one associated with a number of symptoms/complications. Most literature regarding the LT4 dosage deals with the treatment of primary hypothyroidism, whereas a limited number of studies handle the issue of thyroxin replacement after total thyroidectomy. A literature review was performed focusing on all papers dealing with this topic within the last 15 years. Papers that reported a scheme to calculate the proper LT4 dose were collected and compared to set up a review exploring limits and drawbacks of LT4 replacement therapy in the wide population of patients who had undergone thyroidectomy. Most of the methods for monitoring and adjusting thyroid hormone replacement after thyroidectomy for benign disease use LT4 at an empirical dose of approximately 1.6 μg/kg, with subsequent changes according to thyroid function test results and assessments of the patient's symptoms. Approximately 75% of patients require a dose adjustment, suggesting that factors other than body weight play a role in the determination of the proper LT4 dose. Hence, several schemes are reported in the literature for the proper initial dose of LT4. An inadequate level of thyroid hormone levels in these patients can be due to several factors. The most common ones that lead to the necessity of LT4 dose adjustments include lack of compliance, changes in LT4 formulation, dosage errors, increased serum levels of T4-binding globulin, body mass changes, and dietary habits. Moreover, concomitant ingestion of calcium supplements, ferrous sulfate, proton-pump inhibitors, bile acid sequestrants, and sucralfate might influence LT4 absorption and/or metabolism. Furthermore, some gastrointestinal conditions and their treatments can contribute to suboptimal LT4 performance by altering gastric acidity and thereby reducing its bioavailability, particularly in the solid form. Beyond the classic tablet form, new formulations of LT4, such as a soft gel capsule and an oral solution, recently became available. The liquid formulation is supposed to overcome the food and beverages interference with absorption of LT4 tablets.