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Methodist DeBakey Cardiovascular Journal 2017Hypothyroidism is a commonly encountered clinical condition with variable prevalence. It has profound effects on cardiac function that can impact cardiac contractility,... (Review)
Review
Hypothyroidism is a commonly encountered clinical condition with variable prevalence. It has profound effects on cardiac function that can impact cardiac contractility, vascular resistance, blood pressure, and heart rhythm. With this review, we aim to describe the effects of hypothyroidism and subclinical hypothyroidism on the heart. Additionally, we attempt to briefly describe how hypothyroid treatment affects cardiovascular parameters.
Topics: Heart; Heart Diseases; Humans; Hypothyroidism; Prognosis; Risk Assessment; Risk Factors; Thyroid Gland
PubMed: 28740582
DOI: 10.14797/mdcj-13-2-55 -
Australian Journal of General Practice 2021Hypothyroidism and hyperthyroidism are commonly encountered in clinical practice. General practitioners have a central role in the long-term management of these... (Review)
Review
BACKGROUND
Hypothyroidism and hyperthyroidism are commonly encountered in clinical practice. General practitioners have a central role in the long-term management of these conditions.
OBJECTIVE
The aim of this review is to provide an overview of the causes of thyroid function disorders and guidance on management.
DISCUSSION
Optimal management of hypothyroidism relies on an understanding of the potential risks and benefits of therapy versus observation. If levothyroxine (LT4) replacement is commenced in a person with subclinical hypothyroidism on the basis of the presence of possibly relevant hypothyroid symptoms, consideration should be given to ceasing LT4 if no symptomatic benefit is observed. Thyroid stimulating hormone levels below the reference range are associated with atrial fibrillation and osteoporosis, and should be avoided. Treatment modalities for hyperthyroidism include antithyroid medications, radioactive iodine therapy and thyroidectomy. Each is satisfactory, but none is ideal. A patient-centred choice of treatment modality should be individualised, taking into consideration the underlying pathology, age, sex, patient preference and availability of expert thyroid surgical care. Long-term management of patients with hyperthyroidism requires careful consideration of the likely outcomes of treatment including the risk of hypothyroidism.
Topics: Humans; Hyperthyroidism; Hypothyroidism; Iodine Radioisotopes; Thyroid Neoplasms; Thyroxine
PubMed: 33543160
DOI: 10.31128/AJGP-09-20-5653 -
The Journal of Clinical Endocrinology... Sep 2020It is well recognized that some hypothyroid patients on levothyroxine (LT4) remain symptomatic, but why patients are susceptible to this condition, why symptoms persist,... (Review)
Review
CONTEXT
It is well recognized that some hypothyroid patients on levothyroxine (LT4) remain symptomatic, but why patients are susceptible to this condition, why symptoms persist, and what is the role of combination therapy with LT4 and liothyronine (LT3), are questions that remain unclear. Here we explore evidence of abnormal thyroid hormone (TH) metabolism in LT4-treated patients, and offer a rationale for why some patients perceive LT4 therapy as a failure.
EVIDENCE ACQUISITION
This review is based on a collection of primary and review literature gathered from a PubMed search of "hypothyroidism," "levothyroxine," "liothyronine," and "desiccated thyroid extract," among other keywords. PubMed searches were supplemented by Google Scholar and the authors' prior knowledge of the subject.
EVIDENCE SYNTHESIS
In most LT4-treated patients, normalization of serum thyrotropin levels results in decreased serum T3/T4 ratio, with relatively lower serum T3 levels; in at least 15% of the cases, serum T3 levels are below normal. These changes can lead to a reduction in TH action, which would explain the slower rate of metabolism and elevated serum cholesterol levels. A small percentage of patients might also experience persistent symptoms of hypothyroidism, with impaired cognition and tiredness. We propose that such patients carry a key clinical factor, for example, specific genetic and/or immunologic makeup, that is well compensated while the thyroid function is normal but might become apparent when compounded with relatively lower serum T3 levels.
CONCLUSIONS
After excluding other explanations, physicians should openly discuss and consider therapy with LT4 and LT3 with those hypothyroid patients who have persistent symptoms or metabolic abnormalities despite normalization of serum thyrotropin level. New clinical trials focused on symptomatic patients, genetic makeup, and comorbidities, with the statistical power to identify differences between monotherapy and combination therapy, are needed.
Topics: Drug Resistance; Drug Therapy, Combination; Hormone Replacement Therapy; Humans; Hypothyroidism; Practice Patterns, Physicians'; Precision Medicine; Thyroid Function Tests; Thyrotropin; Thyroxine; Treatment Failure; Triiodothyronine
PubMed: 32614450
DOI: 10.1210/clinem/dgaa430 -
American Family Physician Sep 2014Thyroiditis is a general term that encompasses several clinical disorders characterized by inflammation of the thyroid gland. The most common is Hashimoto thyroiditis;...
Thyroiditis is a general term that encompasses several clinical disorders characterized by inflammation of the thyroid gland. The most common is Hashimoto thyroiditis; patients typically present with a nontender goiter, hypothyroidism, and an elevated thyroid peroxidase antibody level. Treatment with levothyroxine ameliorates the hypothyroidism and may reduce goiter size. Postpartum thyroiditis is transient or persistent thyroid dysfunction that occurs within one year of childbirth, miscarriage, or medical abortion. Release of preformed thyroid hormone into the bloodstream may result in hyperthyroidism. This may be followed by transient or permanent hypothyroidism as a result of depletion of thyroid hormone stores and destruction of thyroid hormone-producing cells. Patients should be monitored for changes in thyroid function. Beta blockers can treat symptoms in the initial hyperthyroid phase; in the subsequent hypothyroid phase, levothyroxine should be considered in women with a serum thyroid-stimulating hormone level greater than 10 mIU per L, or in women with a thyroid-stimulating hormone level of 4 to 10 mIU per L who are symptomatic or desire fertility. Subacute thyroiditis is a transient thyrotoxic state characterized by anterior neck pain, suppressed thyroid-stimulating hormone, and low radioactive iodine uptake on thyroid scanning. Many cases of subacute thyroiditis follow an upper respiratory viral illness, which is thought to trigger an inflammatory destruction of thyroid follicles. In most cases, the thyroid gland spontaneously resumes normal thyroid hormone production after several months. Treatment with high-dose acetylsalicylic acid or nonsteroidal anti-inflammatory drugs is directed toward relief of thyroid pain.
Topics: Adrenergic beta-Antagonists; Female; Hormone Replacement Therapy; Humans; Hypothyroidism; Male; Monitoring, Physiologic; Pregnancy; Pregnancy Complications; Prognosis; Thyroid Gland; Thyroiditis; Thyrotropin; Thyroxine; Treatment Outcome; Ultrasonography
PubMed: 25251231
DOI: No ID Found -
Polish Archives of Internal Medicine Mar 2021The negative impact of even subtle maternal thyroid hormone deficiency on the pregnancy outcome and intellectual development of the progeny has been known for many...
The negative impact of even subtle maternal thyroid hormone deficiency on the pregnancy outcome and intellectual development of the progeny has been known for many years, but unfortunately the diagnosis and treatment of subclinical hypothyroidism in pregnant women still evokes controversies. Due to physiological changes in thyroid function and thyroid hormones metabolism during pregnancy, the trimester‑specific reference ranges for thyroid‑stimulating hormone (TSH) and free thyroid hormones should be established. However, because of interassay variability and other confounders including ethnicity and iodine intake, such norms are reliable only for local populations and a specific laboratory method. In turn, the fixed reference ranges suggested by endocrine societies may carry a risk of misclassificating some healthy pregnant women to be hypothyroid. The effect of levothyroxine treatment on pregnancy and children's cognitive outcomes remains unclear. Therapeutic benefits in decreasing miscarriage and preterm delivery rates were observed when intervention was held in the first trimester in women with a TSH level between 2.5 to 10 mU/l, mainly higher than or equal to 4 mU/l. The possible harmful effect of treatment includes preterm delivery, gestational diabetes, hypertension, and pre‑eclampsia. The only 3 prospective, randomized, placebo‑controlled trials evaluating the efficacy of levothyroxine therapy on children's intelligence quotient were started in the second trimester, which may be too late to demonstrate differences between treatment and placebo groups. Awaiting the results of future trials, clinicians should be aware of the fact that low‑dose levothyroxine at a daily dose of 25 to 50 µg is probably not harmful and may be beneficial, but the routine implementation of the therapy in each pregnant women with a TSH level exceeding 2.5 mU/l seems too premature.
Topics: Child; Female; Humans; Hypothyroidism; Infant, Newborn; Pregnancy; Pregnancy Complications; Prospective Studies; Thyrotropin; Thyroxine
PubMed: 32975922
DOI: 10.20452/pamw.15626 -
Medicina 2020The treatment of hypothyroidism is aimed at restoring the euthyroid state. In most cases, the signs and symptoms of thyroid deficiency generally resolve, which is...
The treatment of hypothyroidism is aimed at restoring the euthyroid state. In most cases, the signs and symptoms of thyroid deficiency generally resolve, which is particularly gratifying for the treating physician and mainly, for patients. However, there may be coexisting special situations that can potentially hinder or interfere with a successful treatment, as in the case of the elderly, patients suffering from heart disease, hematological diseases or dyslipidemia, hypothyroid patients who will undergo an emergency surgery, those with chronic kidney failure, or adrenal insufficiency, among others. Besides management of hypothyroidism in time of COVID-19 is also included. Some patients may experience intolerance to treatment and others persistent symptoms of hypothyroidism even under adequate replacement therapy, requiring a special approach. Being aware of these special situations will provide benefits to the patient and will also prevent treatment failure or complications.
Topics: Adrenal Insufficiency; Aged; COVID-19; Humans; Hypothyroidism; SARS-CoV-2
PubMed: 33481737
DOI: No ID Found -
Journal of Endocrinological... Dec 2017There is a frequently encountered subset of hypothyroid patients who are refractory to standard thyroid hormone replacement treatment and require unexpectedly high doses... (Review)
Review
There is a frequently encountered subset of hypothyroid patients who are refractory to standard thyroid hormone replacement treatment and require unexpectedly high doses of levothyroxine. In addition to clinical situations where hypothyroid patients are non-compliant, or where there is the possibility of excipient-induced disease exacerbation (gluten/celiac disease), therapeutic failure may be due to impaired absorption of the administered drug. The common approach to managing patients with unusual thyroxine needs is to escalate the dose of levothyroxine until targeted TSH levels are achieved. This approach can increase the risk for prolonged exposure to supratherapeutic doses of levothyroxine, which increase the chances of adverse outcomes. Repeated adjustments of levothyroxine can also escalate the costs of treatment, as frequent office visits and laboratory tests are required to determine and maintain the desired dose. Clinicians should take a systematic approach to managing patients whom they suspect of having treatment-refractory hypothyroidism. This may include searching for, and adjusting, occult medical conditions and/or other factors that may affect the absorption of levothyroxine, before up-titrating the dose of traditional levothyroxine therapy. Depending on the underlying pathology, another approach that may be considered is to try alternative formulations of levothyroxine that are less susceptible to intolerance issues related to excipients, or, in some cases, to malabsorption. The early discovery of these factors via a thoughtful patient work-up may avoid unnecessary thyroid medication adjustments and their consequences for both patients and clinicians.
Topics: Disease Management; Drug Resistance; Expert Testimony; Hormone Replacement Therapy; Humans; Hypothyroidism
PubMed: 28695483
DOI: 10.1007/s40618-017-0706-y -
Ugeskrift For Laeger May 2023Acquired hypothyroidism is the most common thyroid disease in paediatric patients and in iodine-replete areas mainly due to autoimmune thyroiditis (AIT). Symptoms of... (Review)
Review
Acquired hypothyroidism is the most common thyroid disease in paediatric patients and in iodine-replete areas mainly due to autoimmune thyroiditis (AIT). Symptoms of hypothyroidism are unspecific and insidious for which reason thyroid function tests are often part of a general paediatric assessment. Consequently, only few patients present with pronounced symptoms which include a stunted growth pattern and multiorgan involvement when most extreme. This review provides an overview of the current knowledge on this common endocrinopathy in childhood.
Topics: Humans; Child; Adolescent; Hypothyroidism; Thyroid Diseases; Thyroiditis, Autoimmune; Iodine
PubMed: 37264859
DOI: No ID Found -
Endocrine May 2024To provide an overview of consequences of undertreatment with levothyroxine (LT4) in the common non-communicable disease, hypothyroidism. (Review)
Review
PURPOSE
To provide an overview of consequences of undertreatment with levothyroxine (LT4) in the common non-communicable disease, hypothyroidism.
METHODS
Narrative review of the literature.
RESULTS
Hypothyroidism is globally very prevalent at all age groups and represents a non-communicable disease in which the risks and consequences are preventable. In children and adolescents, the most devastating consequences of undertreatment are poor growth and development. Lack of early treatment in congenital hypothyroidism can lead to permanent damage of brain function. In young to middle-aged adults, consequences are often overlooked, and treatment delayed by many years. The resulting consequences are also at this age group compromised brain and physical functioning but less severe and partly reversible with treatment. The undertreated condition often results in a higher risk of several secondary devastating diseases such as increased cardiovascular disease burden, obesity, hypertension, poor physical capacity, poor quality of life. In young women of fertile age the consequences of undertreatment with LT4 are subnormal fertility, recurrent pregnancy loss, preeclampsia, compromised fetal growth and neurocognitive development. There is a further risk of 30-50% of developing postpartum thyroiditis. In the elderly population care must be given to avoid confusing a slightly high serum TSH as result of physiological age adaptation with a requirement for LT4 treatment in a truly hypothyroid patient.
CONCLUSION
Undertreatment of the preventable non-communicable disease hypothyroidism requires more focus both from caretakers in the healthcare system, but also from the global political systems in order to prevent the personally devastating and socioeconomically challenging consequences.
Topics: Humans; Hypothyroidism; Thyroxine; Female; Pregnancy; Undertreatment
PubMed: 37556077
DOI: 10.1007/s12020-023-03460-1 -
The Science of the Total Environment Apr 2023While fluoride can have thyroid-disrupting effects, associations between low-level fluoride exposure and thyroid conditions remain unclear, especially during pregnancy...
BACKGROUND
While fluoride can have thyroid-disrupting effects, associations between low-level fluoride exposure and thyroid conditions remain unclear, especially during pregnancy when insufficient thyroid hormones can adversely impact offspring development.
OBJECTIVES
We evaluated associations between fluoride exposure and hypothyroidism in a Canadian pregnancy cohort.
METHODS
We measured fluoride concentrations in drinking water and three dilution-corrected urine samples and estimated fluoride intake based on self-reported beverage consumption. We classified women enrolled in the Maternal-Infant Research on Environmental Chemicals Study as euthyroid (n = 1301), subclinical hypothyroid (n = 100) or primary hypothyroid (n = 107) based on their thyroid hormone levels in trimester one. We used multinomial logistic regression to estimate the association between fluoride exposure and classification of either subclinical or primary hypothyroidism and considered maternal thyroid peroxidase antibody (TPOAb) status, a marker of autoimmune hypothyroidism, as an effect modifier. In a subsample of 466 mother-child pairs, we used linear regression to explore the association between maternal hypothyroidism and child Full-Scale IQ (FSIQ) at ages 3-to-4 years and tested for effect modification by child sex.
RESULTS
A 0.5 mg/L increase in drinking water fluoride concentration was associated with a 1.65 (95 % confidence interval [CI]: 1.04, 2.60) increased odds of primary hypothyroidism. In contrast, we did not find a significant association between urinary fluoride (adjusted odds ratio [aOR]: 1.00; 95%CI: 0.73, 1.39) or fluoride intake (aOR: 1.25; 95%CI: 0.99, 1.57) and hypothyroidism. Among women with normal TPOAb levels, the risk of primary hypothyroidism increased with both increasing water fluoride and fluoride intake (aOR water fluoride concentration: 2.85; 95%CI: 1.25, 6.50; aOR fluoride intake: 1.75; 95%CI: 1.27, 2.41). Children born to women with primary hypothyroidism had lower FSIQ scores compared to children of euthyroid women, especially among boys (B coefficient: -8.42; 95 % CI: -15.33, -1.50).
DISCUSSION
Fluoride in drinking water was associated with increased risk of hypothyroidism in pregnant women. Thyroid disruption may contribute to developmental neurotoxicity of fluoride.
Topics: Male; Female; Humans; Pregnancy; Child, Preschool; Fluorides; Drinking Water; Canada; Hypothyroidism; Thyroid Hormones; Pregnancy Complications; Thyrotropin
PubMed: 36764861
DOI: 10.1016/j.scitotenv.2022.161149