Effect of Levothyroxine on Older Patients With Subclinical Hypothyroidism: A Systematic Review and Meta-Analysis

Genetically predicted hypothyroidism, thyroid hormone treatment, and the risk of cardiovascular diseases: a mendelian randomization study

BACKGROUND

In this study, we explored the impact of hypothyroidism and thyroid hormone replacement therapy on the risk of developing cardiovascular diseases, including myocardial infarction, heart failure, and cardiac death, via Mendelian randomization analysis.

METHODS

Genetic instrumental variables related to hypothyroidism, levothyroxine treatment (refer to Participants were taking the medication levothyroxine sodium) and adverse cardiovascular events were obtained from a large publicly available genome-wide association study. Two-sample Mendelian randomization analysis was performed via inverse-variance weighting as the primary method. To ensure the reliability of our findings, we performed MR‒Egger regression, Cochran's Q statistic, and leave-one-out analysis. Additionally, multivariable Mendelian randomization was employed to regulate confounding factors, including systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index (BMI), diabetes, cholesterol, low-density lipoprotein (LDL), triglycerides and metformin. A mediation analysis was conducted to assess the mediating effects on the association between exposure and outcome by treating atrial fibrillation and stroke as mediator variables of levothyroxine treatment and bradycardia as mediator variables of hypothyroidism.

RESULTS

Genetically predicted hypothyroidism and levothyroxine treatment were significantly associated with the risk of experiencing myocardial infarction [levothyroxine: odds ratio (OR) 3.75, 95% confidence interval (CI): 1.80-7.80; hypothyroidism: OR: 15.11, 95% CI: 2.93-77.88]. Levothyroxine treatment was also significantly related to the risk of experiencing heart failure (OR: 2.16, 95% CI: 1.21-3.88). However, no associations were detected between hypothyroidism and the risk of experiencing heart failure or between hypothyroidism or levothyroxine treatment and the risk of experiencing cardiac death. After adjusting for confounding factors, the results remained stable. Additionally, mediation analysis indicated that atrial fibrillation and stroke may serve as potential mediators in the relationships between levothyroxine treatment and the risk of experiencing heart failure or myocardial infarction.

CONCLUSION

The results of our study suggest a positive association between hypothyroidism and myocardial infarction and highlight the potential effects of levothyroxine treatment, the main thyroid hormone replacement therapy approach, on increasing the risk of experiencing myocardial infarction and heart failure.

Effect of Levothyroxine Therapy on the Lipid Profile of Patients With Hypothyroidism: A Systematic Review

Hypothyroidism, also known as underactive thyroid, is a condition where the thyroid gland does not produce enough thyroid hormone. Deficiency or lack of thyroid hormone causes patients to have a slower metabolism, which may lead to secondary medical issues such as weight gain, fatigue, depression, and increased cardiovascular risk. This systematic review aims to explore the effect of levothyroxine therapy on the lipid profile of hypothyroid patients. Through a comprehensive search, 3096 articles were retrieved using keywords such as Hypothyroidism, Levothyroxine, Lipid, Dyslipidemia, and Cholesterol from PubMed, PubMed Central, Google Scholar, and ScienceDirect databases. The Medical Subject Headings (MeSH) strategy was also leveraged to extensively search the PubMed database. Research articles that were published from the year 2020 until May 2024, including randomized control trials, observational studies, meta-analyses, systematic reviews, literature reviews, and case reports, were included in the research. Research papers published before 2020, written in languages other than English, and animal studies were excluded. The 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria were used in the design of the systematic review. Levothyroxine therapy is the treatment of choice in patients suffering from hypothyroidism, and based on our review, the treatment has a positive impact, leading to a significant decrease in total cholesterol, low-density lipoproteins, and triglyceride values in hypothyroid patients. The research highlights the importance of starting timely levothyroxine therapy in hypothyroid patients to maintain normal lipid levels and reduce the associated cardiovascular risk.

Association of subclinical hypothyroidism with metabolic syndrome and its components among outpatients with first-episode drug-naïve major depressive disorder: a large-scale cross-sectional study

Both metabolic syndrome (MetS) and subclinical hypothyroidism (SCH) are prevalent in major depressive disorder (MDD) patients. However, their relationship in this population remains unknown. The study assessed the association between SCH and MetS in 1706 first-episode drug-naïve (FEDN) MDD patients. We also compared the relationship between MetS and clinical symptoms in patients with and without comorbid SCH. The Positive and Negative Syndrome Scale positive subscale, the Hamilton Anxiety Rating Scale, and the Hamilton Depression Rating Scale were used to detect clinical symptoms. Serum levels of free triiodothyronine, free thyroxine, thyroid stimulating hormone (TSH), anti-thyroglobulin, thyroid peroxidases antibody, cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and fasting glucose were measured. The Area Under the Curve (AUC) was used to test the performance of serum TSH in identifying MetS patients. The prevalence of MetS and SCH was 34.5% (n = 585) and 61% (n = 1034), respectively. The presence of SCH increased the risk of MetS, hyperglycemia, hypertension, obesity, and low HDL-C by 4.91, 3.51, 3.54, 2.02, and 2.34 times, respectively. Serum TSH had a nice ability to distinguish MetS patients from non-MetS patients (AUC value = 0.77). MetS and its components exhibited a positive association with clinical profiles only in SCH patients, but not in non-SCH patients. Taken together, our study suggested SCH was closely related to MetS and might play a vital role in the relationship between MetS and clinical symptoms. Regular thyroid function checks might help early detect MetS.

Neuroendocrine Parathyroid Tumors: Quality of Life in Patients with Primary Hyperparathyroidism

Tumors of the parathyroid glands, when associated with PTH (parathyroid hormone) excess, display a large area of complications; in addition to the classical clinical picture of primary hyperparathyroidism (PHP), a complex panel of other symptoms/signs can be identified, including memory and cognitive impairment, chronic asthenia/fatigue, reduced muscle functionality, depressive mood, non-specific bone pain, and loss of sleep quality. The perception of quality of life (QoL) can be supplementarily enhanced by their progressive onset, which makes many patients not be fully aware of them. Their improvement was reported very early after parathyroidectomy (PTx), yet the level of statistical evidence does not qualify these non-classical elements as standalone indications for PTx. Our objective is introducing an up-to-date on QoL scores with regards to the patients diagnosed with PHP, particularly taking into consideration PHP management from baseline to post-operatory outcome, including in cases with multiple endocrine neoplasia. This is a narrative review of literature. We revised full-length papers published in English through PubMed research conducted between January 2018 and May 2023 by using the key words "quality of life" and "primary hyperparathyroidism". We particularly looked at data on self-reported QoL (through questionnaires). We excluded from the search the studies focused on non-PTH related hypercalcemia, secondary, and/or renal/tertiary hyperparathyroidism, and vitamin D supplementation. Overall, we identified 76 papers and selected for the final analysis 16 original studies on QoL and PHP (a total of 1327 subjects diagnosed with syndromic and non-syndromic PHP). The studies with the largest number of individuals were of 92, 104, 110, 134, 159, as well as 191. A few cohorts (n = 5) were of small size (between 20 and 40 patients in each of them). Concerning the study design, except for 2 papers, all the mentioned studies provided longitudinal information, particularly the timeframe from baseline (before PTx) and after surgery. The post-operatory follow-up was of 3-6 months, but mostly between 1 and 3 years (maximum a decade of surveillance). The age of the patients varies between medians of 56, 62, 64, and 68 years. Most frequent questionnaires were SF-36, PHPQoL, and PAS. Despite not being unanimously similar, an overall reduced score of QoL in patients with PHP versus controls was registered, as well as general improvement following PTx. Variations of QoL results might have a multifactorial background from different comorbidities, studied populations, technical aspects of collecting the data, etc. QoL scores in PHP represents a complex heterogeneous picture, from their correlation with clinical features and lab assays (e.g., the level of serum calcium), the associated comorbidities (such as multiple endocrine neoplasia syndromes), up to the assessment of the QoL improvement after parathyroidectomy (PTx). While current studies do not unanimously agree on each QoL domain, the assessment of QoL might represent a supplementary argument to consider when deciding for PTx, especially in asymptomatic cases and in patients who do not fit into well-known categories of surgery candidates, according to current guidelines, thus assessing QoL in PHP is part of a current research gap. QoL evaluation in PHP remains an open issue, towards which awareness should be cultivated by both endocrinologists and surgeons. The introduction of a routine evaluation of the QoL scores in patients, as well as the selection of the most appropriate questionnaire(s), represents an open chapter thus awareness in mandatory.

Treating subclinical hypothyroidism in individuals with or without mental health problems -A Delphi based expert consensus study in two countries

Background

Subclinical hypothyroidism (SCH) is a common endocrine problem with prevalence estimates between 4% and 20%. Symptoms are often non-specific but can substantially affect well-being leading to repeated medical consultations. The effect of thyroid hormone replacement therapy (THRT) in patients with SCH remains uncertain. Current guidelines, limited by the lack of high-quality evidence, have been controversial with limited adherence in clinical practice.

Methods

Three-round modified Delphi method to establish consensus regarding diagnosis and treatment of individuals with SCH with and without affective disorder or anxiety, conducted with clinicians from three specialties, general practice, endocrinology and psychiatry, and two countries, Sweden and the United Kingdom.

Results

Sixty clinicians, 20 per specialty, were recruited. Fifty-three (88%) participants completed all three rounds. The participants reached consensus on five of the 26 practice statements that (a) repeated testing was required for the diagnosis of subclinical hypothyroidism, (b) antibody screening should usually occur, and (c and d) antibody screening would strengthen the indication for thyroid hormone replacement therapy in both individuals with or without affective disorder or anxiety. The participants disagreed with (e) a requirement of a TSH threshold ≥ 20 mIU/L for thyroid hormone replacement therapy start. Psychiatrists and GPs but not endocrinologists, agreed that there was a frequent discrepancy between laboratory results and clinical symptoms, and disagreed that testing for thyroid dysfunction was overused in patients presenting with depression or anxiety, or fatigue.

Conclusions

In many aspects, attitudes toward diagnosing and treating SCH remain diverse. The inability of our Delphi panel to achieve consensus on most items and the disagreement with a TSH ≥ 20 mIU/L threshold for treatment suggest that the concept of SCH may need rethinking with a better understanding of the hypothalamic-pituitary-thyroid physiology. Given that the scientific evidence is currently not conclusive, guidelines in this area should not be taken as definitive.

Clinical symptoms, thyroid dysfunction, and metabolic disturbances in first-episode drug-naïve major depressive disorder patients with suicide attempts: A network perspective

BACKGROUNDS

Co-occurrence of thyroid dysfunction, metabolic disturbances, and worsening clinical symptoms in major depressive disorder (MDD) patients with suicidal attempts (SA) are common. However, their relationship in SA patients remains unexplored. We aimed to (1) determine the independent association of thyroid dysfunction, clinical symptoms, and metabolic disturbances with SA; and (2) identify their interactions in SA patients via the network approach.

METHODS

1718 FEDN MDD patients were recruited. Depressive, anxiety, and psychotic symptoms were assessed by the Hamilton Rating Scale for Depression (HAMD), the Hamilton Rating Scale for Anxiety (HAMA), and the Positive and Negative Syndrome Subscale positive subscale, respectively. The serum levels of thyroid hormones and other metabolic parameters were assessed. Logistic regression model was applied to determine the correlates of SA. Network analysis was applied to determine the interaction between thyroid dysfunction, clinical symptoms, and metabolic disturbances.

RESULTS

SA patients had significant worse metabolic disturbances, thyroid dysfunction, and clinical symptoms than non-SA patients. Thyroid peroxidases antibody, thyroid stimulating hormone (TSH), HAMD scores, HAMA scores, and systolic blood pressure was independently associated with SA. Network analysis suggested that TSH was the hub of the network, exhibiting substantial associations with metabolic disturbances, anxiety, and psychotic symptoms in SA patients.

CONCLUSIONS

Our work highlights the predominant role of serum TSH levels in the pathophysiology of SA. Regular thyroid function tests might help early detect SA. Targeting increased TSH levels may help reduce metabolic disturbances and clinical symptoms in SA patients.

Association between thyroid dysfunction, metabolic disturbances, and clinical symptoms in first-episode, untreated Chinese patients with major depressive disorder: Undirected and Bayesian network analyses

AIMS

Thyroid dysfunction and metabolic disturbances are common in major depressive disorder (MDD) patients. We aimed to assess the relationship between thyroid dysfunction, metabolic disturbances, and clinical symptoms in Chinese first-episode, drug-naïve (FEDN) MDD patients using undirected and Bayesian network methods.

METHODS

1718 FEDN MDD patients were recruited. Serum levels of free triiodothyronine (FT3), free thyroxine (FT4), thyroid stimulating hormone (TSH), anti-thyroglobulin (TgAb), thyroid peroxidases antibody (TPOAb), total cholesterol (TC), total triglycerides (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), and glucose were assessed. Blood pressure and body mass index were measured. Hamilton Rating Scale for Depression (HAMD), Hamilton Rating Scale for Anxiety, and positive subscale of Positive And Negative Syndrome Scales were used to detect clinical symptoms. An undirected network with EBICglasso default and a directed acyclic graph (DAG) using the Bayesian network approach was conducted.

RESULTS

The prevalence rates of clinical symptoms, thyroid dysfunction, and metabolic dysfunction were as follows: anxiety (n=894, 52%), psychotic symptoms (171, 10%), subclinical hypothyroidism (SCH, n=1041, 61%), abnormal TgAb (n=297, 17%), abnormal TPOAb (n=438, 25%), hyperthyroidism (n=5, 0.3%), hypothyroidism (n=3, 0.2%), hyperglycemia (n=241, 14%), hypertriglyceridemia (n=668, 39%), low HDL-C (n=429, 25%), hypercholesterolemia (421, 25%), abnormal TC (357, 21%), abnormal LDL-C (185, 11%). overweight or obesity (n=1026, 60%), and hypertension (n=92, 5.4%). Both networks demonstrated serum TSH and TC levels and the severity of depression played an important role in the pathophysiology of MDD.

CONCLUSIONS

MDD patients may have thyroid and metabolic dysfunction in the early stage. Targeting hypercholesterolemia, depressive symptoms, and SCH in MDD patients may hold promise in reducing clinical symptoms, metabolic disturbances, and thyroid dysfunction.

The Relationship between Gastrointestinal Health, Micronutrient Concentrations, and Autoimmunity: A Focus on the Thyroid

Currently, there is a lack of understanding of why many patients with thyroid dysfunction remain symptomatic despite being biochemically euthyroid. Gastrointestinal (GI) health is imperative for absorption of thyroid-specific nutrients as well as thyroid function directly. This comprehensive narrative review describes the impact of what the authors have conceptualized as the “nutrient–GI–thyroid axis”. Compelling evidence reveals how gastrointestinal health could be seen as the epicenter of thyroid-related care given that: (1) GI conditions can lower thyroid-specific nutrients; (2) GI care can improve status of thyroid-specific nutrients; (3) GI conditions are at least 45 times more common than hypothyroidism; (4) GI care can resolve symptoms thought to be from thyroid dysfunction; and (5) GI health can affect thyroid autoimmunity. A new appreciation for GI health could be the missing link to better nutrient status, thyroid status, and clinical care for those with thyroid dysfunction.