The Role of Inositol in Thyroid Physiology and in Subclinical Hypothyroidism Management

Abstract

Myo-Inositol (MYO) is the most abundant stereoisomer of inositols’ family, cyclic polyols with 6 hydroxyl groups. Myo-Inositol has a relevant role in thyroid function and autoimmune diseases, as a precursor of phosphoinositides that takes part in the phosphatidylinositol (PI) signal transduction pathway. Among phosphoinositides, phosphatidylinositol 4,5- bisphosphate (PIP2) is the precursor of inositol triphosphates (IP3), second messenger of several hormones including thyroid-stimulating hormone (TSH). As a second messenger in the phospholipase C (PLC)-dependent inositol phosphate Ca2+/DAG pathway, Myo-Inositol is essential to produce H2O2 required for the synthesis of thyroid hormones. Consequently, depletion of Myo-Inositol or impaired inositol dependent TSH signaling pathway may predispose to the development of some thyroid diseases, such as hypothyroidism. Many clinical studies have shown that after treatment with Myo-Inositol plus Selenium (MYO+Se), TSH levels significantly decreased in patients with subclinical hypothyroidism with or without autoimmune thyroiditis. The TSH reduction was accompanied by a decline of antithyroid autoantibodies. Moreover, Myo-Inositol supplementation seemed to be involved also in the management of thyroidal benign nodules, with a possible effect in the size reduction. This review proposes a summary of the role of inositol, especially of Myo-Inositol, in the thyroidal physiology and its contribution on the management of some thyroid diseases.

Redefining the Cut-Off Ranges for TSH Based on the Clinical Picture, Results of Neuroimaging and Laboratory Tests in Unsupervised Cluster Analysis as Individualized Diagnosis of Early Schizophrenia

“…There are few studies comparing the levels of the above-mentioned biomarkers during the development of the disease, explaining the molecular mechanism of psychosis [109]. In the metabolomic studies of the saliva of patients with the first episode of psychosis, attention was drawn to a reduced metabolism of aromatic amino acids, altered glutamine metabolism and increased metabolism of the tricarboxylic acid cycle, compared to those with a high clinical risk of psychosis before its occurrence [110][111][112][113][114]. It showed a profile of changes with greater intensity at the onset of schizophrenia, characteristic of the disease stage.…”

The Influence of Oxidative Stress on Thyroid Diseases

“…Thyroid cells release oxidases, which catalyse ROS production [42][43][44]. Inositols are also involved in thyroid hormone synthesis and normal thyroid function, activating a cascade of processes including regulating TSH-dependent signalling (as a TSH transmitter) and generating H 2 O 2 production used for iodination and coupling of iodotyrosine and iodothyronine [45][46][47][48]. Inositol deficiency or impairment of inositol cascades may result in insufficient synthesis of thyroid hormones, leading to hypothyroidism, which may be further compounded by an increased need for inositols in response to high TSH levels [45,48].…”

Falsely elevated serum estradiol in woman of reproductive age led to unnecessary intervention and delayed fertility opportunity: a case report and literature review

“…Inositol, including D-chiro-inositol and myo-inositol, have been classified as insulin-sensitizers [15]. Moreover, myo-inositol is also essential to produce H2O2 required for the synthesis of thyroid hormones, and may be a suitable therapy for PCOS patients to improve the accompanying endocrine cross-talk disorders, such as insulin resistance and hypothyroidism [16].…”