Related Experiment Video
Updated: Jul 14, 2026
04:39
Generation of a Mouse Spontaneous Autoimmune Thyroiditis Model
Published on: March 17, 2023
[Subclinical hypothyroidism and pregnancy].
1Service de médecine interne, hôpital de Hautepierre, 67098 Strasbourg cedex, France. jean-louis.schlienger@chru-strasbourg.fr
Summary
Routine screening and treatment for subclinical hypothyroidism during pregnancy are not recommended. Current evidence does not support the efficacy of levothyroxine in pregnant individuals with mild thyroid dysfunction.
Area of Science:
- Endocrinology
- Reproductive Medicine
- Maternal-Fetal Medicine
Context:
- Pregnancy significantly alters thyroid homeostasis, especially with low iodine intake.
- Subclinical hypothyroidism is characterized by elevated TSH (thyroid-stimulating hormone) with normal thyroxine and triiodothyronine levels.
- Established risks of subclinical hypothyroidism include maternal and prenatal morbidity, and adverse effects on child neurodevelopment.
Purpose:
- To evaluate the necessity of routine screening and levothyroxine treatment for subclinical hypothyroidism during pregnancy.
- To review the current evidence regarding the efficacy of levothyroxine in managing subclinical hypothyroidism in pregnant individuals, particularly with TSH levels between 3 and 4 mU/l.
Summary:
- Subclinical hypothyroidism in pregnancy presents with elevated TSH but normal thyroid hormone levels.
- While risks are known, robust clinical trials demonstrating levothyroxine's efficacy for subclinical hypothyroidism in pregnancy are lacking.
- The TSH cut-off for diagnosis remains under discussion, complicating treatment decisions.
Impact:
- Current evidence does not support routine screening for subclinical hypothyroidism in pregnancy.
- Levothyroxine treatment for subclinical hypothyroidism in pregnancy is not routinely recommended due to insufficient evidence of efficacy.
- Further research is needed to clarify diagnostic criteria and treatment benefits in this population.
Related Concept Videos
01:25Hyperthyroidism I: Introduction
Hyperthyroidism is a type of thyrotoxicosis characterized by the thyroid gland's overproduction of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). This hormone excess increases the basal metabolic rate and enhances sensitivity to catecholamines.DiagnosisDiagnosis is based on clinical features and biochemical testing. It typically shows suppressed thyroid-stimulating hormone (TSH) levels below 0.4 mIU/L, with elevated free T3 and/or T4. Additional tests, including thyroid...
01:23Hypothyroidism II: Pathophysiology
Hypothyroidism is a disorder characterized by insufficient production of thyroid hormones, which regulate metabolism, energy balance, and multiple organ systems.TypesHypothyroidism is classified based on the level of dysfunction. Primary hypothyroidism results from intrinsic thyroid gland dysfunction, causing reduced hormone production despite normal or increased stimulation. Secondary hypothyroidism arises from inadequate thyroid-stimulating hormone (TSH) secretion by the pituitary. Tertiary...
01:27Hyperthyroidism II: Pathophysiology
Hyperthyroidism is a hypermetabolic state caused by elevated levels of thyroid hormones, triiodothyronine (T3) and thyroxine (T4). It results from dysregulation at the thyroid, pituitary, or immune system level and affects multiple organ systems.PathophysiologyThe most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder in which antibodies, specifically thyroid-stimulating antibodies (TSAb), a subtype of TSH receptor antibodies (TRAb), bind to and activate TSH receptors...
01:28Graves' Disease I: Introduction
Graves' disease is an autoimmune disorder that causes hyperthyroidism, or overactivity of the thyroid gland. It results from autoantibodies called thyroid-stimulating immunoglobulins (TSIs), which bind to thyroid-stimulating hormone (TSH) receptors, leading to overstimulation of hormone production and a hypermetabolic state.EtiologyAlthough considered idiopathic, Graves’ disease has well-established contributing factors. There is a strong genetic component, with increased prevalence in...
01:24Graves Disease II: Pathophysiology
Graves’ disease is an autoimmune disorder characterized by the production of thyroid-stimulating immunoglobulins (TSI) that activate TSH receptors, leading to excessive synthesis and release of thyroid hormones (T3 and T4) and resulting in hyperthyroidism.Among all causes of hyperthyroidism, Graves’ disease is the most common and can happen at any age, though it is more frequent in women. It produces a hypermetabolic state with features such as weight loss, tachycardia, tremor, and heat...
01:20Synthesis and Regulation of Thyroid Hormones
Low blood levels of the thyroid hormones — triiodothyronine (T3) and thyroxine (T4) — signal the hypothalamus to release the thyrotropin-releasing hormone (TRH). TRH then reaches the pituitary gland and stimulates the release of thyroid-stimulating hormone(TSH) into the bloodstream.
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...