Risk Factors for Thyroid Function Test Abnormalities During Pregnancy: A Systematic Review of the Literature to Validate Current Risk Factors and Identify Novel Ones
Background/Objectives: There is evidence of overtreatment in patients with subclinical hypothyroidism (SCH). We aimed to identify the proportion of patients treated for SCH and the determinants of thyroid hormone therapy initiation. Methods: We included a random sample of adult Veterans diagnosed with SCH from 1 January 2016 to 31 December 2018 and conducted univariate and multivariable logistic regression to identify factors associated with levothyroxine initiation. Results: Out of 229 Veterans with SCH [90.0% male, 87.2% White, 99.1% non-Hispanic, median age (interquartile range; IQR) 68 (17) years], 27.5% were treated with levothyroxine. The treated group had a higher proportion of White patients (95.2% vs. 84.2%, p = 0.039), a higher thyrotropin level [median (IQR), 6.98 (2.06) mIU/L vs. 6.14 (1.10) mIU/L, p = 0.0002], a higher proportion of patients with thyrotropin level ≥ 10 mIU/L (11.1% vs. 3.0%, p = 0.021), a lower frequency of confirmatory thyroid testing before initiating levothyroxine (49.2% vs. 97.0%, p < 0.0001), and a similar frequency of thyroid autoimmunity testing (3.2% vs. 0.6%, p = 0.18) compared to the untreated group. In a multivariable logistic regression analysis, White race (OR = 4.50, 95% CI 1.19 to 17.08, p = 0.026) and index thyrotropin level [OR = 1.71, 95% CI 1.24 to 2.35, p = 0.001; for every SD increase (1.6 mIU/L)] were associated with higher odds of treatment. Conclusions: Three in 10 Veterans with SCH received levothyroxine, often based on a single abnormal thyroid test without autoimmunity assessment. White race and higher thyrotropin level were linked to increased odds of starting treatment, indicating potential disparities and the influence of SCH severity on decision-making.
Risk Factors for Thyroid Dysfunction in Pregnancy: An Individual Participant Data Meta-Analysis
Background: International guidelines recommend targeted screening to identify gestational thyroid dysfunction. However, currently used risk factors have questionable discriminative ability. We quantified the risk for thyroid function test abnormalities for a subset of risk factors currently used in international guidelines. Methods: We included prospective cohort studies with data on gestational maternal thyroid function and potential risk factors (maternal age, body mass index [BMI], parity, smoking status, pregnancy through in vitro fertilization, twin pregnancy, gestational age, maternal education, and thyroid peroxidase antibody [TPOAb] or thyroglobulin antibody [TgAb] positivity). Exclusion criteria were pre-existing thyroid disease and use of thyroid interfering medication. We analyzed individual participant data using mixed-effects regression models. Primary outcomes were overt and subclinical hypothyroidism and a treatment indication (defined as overt hypothyroidism, subclinical hypothyroidism with thyrotropin >10 mU/L, or subclinical hypothyroidism with TPOAb positivity). Results: The study population comprised 65,559 participants in 25 cohorts. The screening rate in cohorts using risk factors currently recommended (age >30 years, parity ≥2, BMI ≥40) was 58%, with a detection rate for overt and subclinical hypothyroidism of 59%. The absolute risk for overt or subclinical hypothyroidism varied <2% over the full range of age and BMI and for any parity. Receiver operating characteristic curves, fitted using maternal age, BMI, smoking status, parity, and gestational age at blood sampling as explanatory variables, yielded areas under the curve ranging from 0.58 to 0.63 for the primary outcomes. TPOAbs/TgAbs positivity was associated with overt hypothyroidism (approximate risk for antibody negativity 0.1%, isolated TgAb positivity 2.4%, isolated TPOAb positivity 3.8%, combined antibody positivity 7.0%; p < 0.001), subclinical hypothyroidism (risk for antibody negativity 2.2%, isolated TgAb positivity 8.1%, isolated TPOAb positivity 14.2%, combined antibody positivity 20.0%; p < 0.001) and a treatment indication (risk for antibody negativity 0.2%, isolated TgAb positivity 2.2%, isolated TPOAb positivity 3.0%, and combined antibody positivity 5.1%; p < 0.001). Twin pregnancy was associated with a higher risk of overt hyperthyroidism (5.6% vs. 0.7%; p < 0.001). Conclusions: The risk factors assessed in this study had poor predictive ability for detecting thyroid function test abnormalities, questioning their clinical usability for targeted screening. As expected, TPOAb positivity (used as a benchmark) was a relevant risk factor for (subclinical) hypothyroidism. These results provide insights into different risk factors for gestational thyroid dysfunction.
Interventions to improve symptomatology in patients with hypothyroidism and persistent symptoms: A systematic review.
Abstract Background Levothyroxine (LT4) monotherapy is the standard treatment for hypothyroidism; however, 10–15% of patients have persistent hypothyroid symptoms despite normalizing thyroid hormone levels with LT4. This study aims to summarize the best available evidence on interventions to improve symptomatology in patients with hypothyroidism and persistent symptoms. Methods A systematic search was conducted in March 2022 for randomized controlled trials (RCTs) and observational studies on interventions for adult patients with persistent hypothyroid symptoms despite biochemical euthyroidism on thyroid hormone replacement. Results Of 277 articles, seven fulfilled the inclusion criteria. 455 participants were included. Most intervention participants were female (78.6%) with a mean age of 47.5 years. Five clinical trials evaluating ginger (vs. starch), L-carnitine (vs. placebo), combination LT4 and liothyronine (LT3) (vs. LT4 or placebo), and surgery for patients with serum antithyroid peroxidase (TPO Ab) titers greater than 1000 IU/ml (vs. LT4) found inconsistent improvement in hypothyroidism related symptoms and general health. Of these clinical trials, the use of ginger and surgery showed the largest improvements in fatigue scores. One observational study comparing thyroidectomy vs observation found no impact difference on general health. Lastly, another observational study evaluating combination LT4/LT3 (vs. LT4 monotherapy) found improvement in fatigue and QoL. There were 31 (12%) adverse events in the intervention group and 18 (10.8%) in the comparator group. Conclusions There is no high-quality evidence supporting any intervention for persistent symptoms in hypothyroidism. Available evidence, limited by the risk of bias, inconsistency, and heterogeneity, suggests that some persistent symptoms, particularly fatigue, could improve with ginger and thyroidectomy. Trial registry number:PROSPERO (CRD42022318720)
THU664 Discontinuation Of Low-dose Levothyroxine Therapy For Patients With Subclinical Hypothyroidism Is Feasible: A Pilot, Randomized, Double-blind, Placebo-controlled Trial
Abstract Disclosure: S. Maraka: None. R. Owen: None. N.M. Singh Ospina: None. M. Knox: None. T. Dodds: None. H. Spencer: None. A. Albashaireh: None. A. Shah: None. S. Syed: None. S. Naqvi: None. H. Motahari: None. S. Thumma: None. E. Ambrogini: None. J.P. Brito: None. Objective: Levothyroxine (LT4) therapy has not been shown to improve quality of life (QoL), thyroid-related symptoms, cardiovascular events, or mortality for patients with subclinical hypothyroidism (SCH) in clinical trials. We conducted this pilot, double-blind, placebo-controlled clinical trial to evaluate the effects of LT4 discontinuation among adults with SCH. Methods: We aimed to randomize 50 adults 1:1 to continue receiving LT4 (25-75 mcg/day) for SCH or discontinue it (switch to placebo). The primary outcome was feasibility. Secondary outcomes included changes in QoL measures (Thyroid-specific QoL Patient-Reported Outcome [ThyPRO]-Hypothyroid Symptoms and Tiredness scores, EuroQoL 5-Dimension Self-Report Questionnaire [EQ-5D]) assessed at baseline and 6 months post-randomization, and incidence of adverse events (overt hypothyroidism, hyperthyroidism, atrial fibrillation, stroke, acute coronary syndrome, heart failure, fracture, mortality). Higher scores for ThyPRO indicate more symptoms and tiredness and for EQ-5D, better health state. Data are reported as mean (standard deviation). Analysis of covariance model adjusting for age and baseline measure of the variable was performed for the outcomes based on the intention-to-treat principle. Results: Fifty participants were enrolled (33% recruitment rate); 24 were randomized to the LT4 and 26 to the discontinuation group. Five patients were excluded post-randomization due to lack of ascertainment of SCH diagnosis (final N=45; 21 LT4, 24 discontinuation). There was no statistically significant difference at baseline between the discontinuation and LT4 groups in age [65.7 (10.6) vs. 71.0 (7.9) yrs], gender (male 75 vs. 86%), LT4 dose (25 mcg; 29.2 vs. 33.3%, 50 mcg; 54.2 vs. 47.6%, 75 mcg; 16.7 vs. 19.0%), TSH [3.1 (1.0) vs. 3.2 (1.4) mIU/L], TPOAb positivity (17 vs. 19%), ThyPRO-Hypothyroid Symptoms [27.1 (20.4) vs. 21.1 (18.4)] and Tiredness score [33.2 (23.7) vs. 31.1 (23.9)], and EQ-5D [0.746 (0.229) vs. 0.758 (0.193)]. A patient in the discontinuation group withdrew for personal reasons (98% completion rate). Two patients in the discontinuation group met study criteria to restart LT4 (TSH>10 mIU/L; n=1, fatigue; n=1). At final visit, 34.8% of patients in the discontinuation group had mild SCH compared to 9.5% of patients on LT4 (p=0.07). There was no statistically significant difference between the discontinuation and LT4 groups in ThyPRO-Hypothyroid Symptoms [28.3 (22.8) vs. 22.9 (19.5)], Tiredness [27.6 (22.8) vs. 32.8 (22.1)], and EQ-5D score [0.750 (0.232) vs. 0.741 (0.180)]. A patient suffered rib fracture (placebo); no other adverse event of interest was reported. Conclusion: This pilot clinical trial showed the feasibility and safety of discontinuing LT4 in patients with SCH. These findings support proceeding with a larger multi-site clinical trial to fully assess the effects of LT4 discontinuation. Presentation: Thursday, June 15, 2023
Appropriateness of Levothyroxine Prescription: A Multicenter Retrospective Study
Abstract Context Levothyroxine is one of the most prescribed medications in the United States. Objective This study explores the appropriateness of levothyroxine prescriptions. Methods A retrospective multicenter study was conducted on adult patients who were prescribed levothyroxine for the first time between 2017 and 2020 at three academic centers in the United States. We classified each case of levothyroxine initiation into one of three mutually exclusive categories: appropriate (clinically supported), indeterminate (clinically unclear), or nonevidence based (NEB, not clinically supported). Results A total of 977 participants were included. The mean age was 55 years (SD 19), there was female (69%) and White race predominance (84%), and 44% had possible hypothyroid symptoms. Nearly half of the levothyroxine prescriptions were considered NEB (528, 54%), followed by appropriate (307, 31%) and indeterminate (118, 12%). The most common reason for NEB prescription was an index thyrotropin (TSH) value of less than 10 mIU/L without previous TSH or thyroxine values (131/528, 25%), for appropriate prescription, was overt hypothyroidism (163/307, 53%), and for an indeterminate prescription was a nonconfirmed subclinical hypothyroidism with TSH greater than or equal to 10 mIU/L (no confirmatory testing) (51/118, 43%). In multivariable analysis, being female (odds ratio [OR]: 1.3; 95% CI, 1.0-1.7) and prescription by a primary care provider (OR: 1.5; 95% CI, 1.2-2.0) were associated with NEB prescriptions. Conclusion There is a considerable proportion of NEB levothyroxine prescriptions. These results call for additional research to replicate these findings and to explore the perspective of those prescribing and receiving levothyroxine.
Determinants for Thyroid Hormone Replacement Therapy in Subclinical Hypothyroidism: A Multicenter Electronic Health Records-Based Study
Abstract Objective This work aims to guide clinicians practicing endocrinology in the use of telehealth (synchronous patient-clinician visits conducted over video or telephone) for outpatient care. Participants The Endocrine Society convened a 9-member panel of US endocrinologists with expertise in telehealth clinical care, telehealth operations, patient-centered care, health care delivery research, and/or evidence-based medicine. Evidence The panel conducted a literature search to identify studies published since 2000 about telehealth in endocrinology. One member extracted a list of factors affecting the quality of endocrine care via telehealth from the extant literature. The panel grouped these factors into 5 domains: clinical, patient, patient-clinician relationship, clinician, and health care setting and technology. Consensus Process For each domain, 2 or 3 members drew on existing literature and their expert opinions to draft a section examining the effect of the domain’s component factors on the appropriateness of telehealth use within endocrine practice. Appropriateness was evaluated in the context of the 6 Institute of Medicine aims for health care quality: patient-centeredness, equity, safety, effectiveness, timeliness, and efficiency. The panel held monthly virtual meetings to discuss and revise each domain. Two members wrote the remaining sections and integrated them with the domains to create the full policy perspective, which was reviewed and revised by all members. Conclusions Telehealth has become a common care modality within endocrinology. This policy perspective summarizes the factors determining telehealth appropriateness in various patient care scenarios. Strategies to increase the quality of telehealth care are offered. More research is needed to develop a robust evidence base for future guideline development.
TSH and FT4 Reference Intervals in Pregnancy: A Systematic Review and Individual Participant Data Meta-Analysis
Abstract Context Interpretation of thyroid function tests during pregnancy is limited by the generalizability of reference intervals between cohorts due to inconsistent methodology. Objective (1) To provide an overview of published reference intervals for thyrotropin (TSH) and free thyroxine (FT4) in pregnancy, (2) to assess the consequences of common methodological between-study differences by combining raw data from different cohorts. Methods (1) Ovid MEDLINE, EMBASE, and Web of Science were searched until December 12, 2021. Studies were assessed in duplicate. (2) The individual participant data (IPD) meta-analysis was performed in participating cohorts in the Consortium on Thyroid and Pregnancy. Results (1) Large between-study methodological differences were identified, 11 of 102 included studies were in accordance with current guidelines; (2) 22 cohorts involving 63 198 participants were included in the meta-analysis. Not excluding thyroid peroxidase antibody–positive participants led to a rise in the upper limits of TSH in all cohorts, especially in the first (mean +17.4%; range +1.6 to +30.3%) and second trimester (mean +9.8%; range +0.6 to +32.3%). The use of the 95th percentile led to considerable changes in upper limits, varying from –10.8% to –21.8% for TSH and –1.2% to –13.2% for FT4. All other additional exclusion criteria changed reference interval cut-offs by a maximum of 3.5%. Applying these findings to the 102 studies included in the systematic review, 48 studies could be used in a clinical setting. Conclusion We provide an overview of clinically relevant reference intervals for TSH and FT4 in pregnancy. The results of the meta-analysis indicate that future studies can adopt a simplified study setup without additional exclusion criteria.