3,368 research outputs found
Central hypothyroidism
No full textCentral Hypothyrodism (CeH) is the hypothyroid condition due to an insufficient stimulation by thyrotropin (TSH) of an otherwise normal thyroid gland. CeH is about 1,000-fold more rare than primary hypothyroidism and raises several challenges for the clinicians, mainly because they cannot rely on the systematic use of the “reflex TSH strategy” for diagnosis or therapy monitoring. Therefore, CeH diagnosis is suspected and detectable in patients with known hypothalamic-pituitary diseases, whereas it can be frequently missed in those with a previously unknown pituitary involvement. L-thyroxine replacement in CeH should rely on the combined evaluation of several biochemical and clinical parameters in order to overcome the lack of accuracy of the single index. The management of CeH patients is further complicated by the frequent combination with other pituitary deficiencies and their specific replacement
TSH-induced hyperthyroidism caused by a pituitary tumor
No full textBACKGROUND: A 45-year-old man presented with frontal headache and visual disturbances to our clinic. For the previous 5 years, he had been receiving treatment for long-lasting mild hyperthyroidism with antithyroid therapy, but therapy had not been carefully followed. During the last 2 years he had also complained of erectile dysfunction and loss of libido. On physical examination, he had a small goiter, normal skin, no Graves' ophthalmopathy, normal BMI, and reduced testis volume and pubic hair. INVESTIGATIONS: Serum levels of free T3 and T4, serum prolactin, testosterone, serum gonadotropins, insulin-like growth factor 1, adrenocorticotropic hormone, and cortisol were measured. MRI scan, TSH-releasing hormone test, and T3 suppression test were carried out. Levels of pituitary glycoprotein hormone alpha-subunit and sex-hormone-binding protein were also measured. DIAGNOSIS: Hyperthyroidism caused by a mixed pituitary adenoma that secretes prolactin and TSH. MANAGEMENT: Trans-sphenoidal resection of the pituitary tumor. After surgery, T3 suppression test failed to completely suppress TSH secretion, which suggested a persistence of residual adenomatous cells. Hyperthyroidism and hypogonadism recurred after 5 years, therefore, treatment with lanreotide was initiated, and resulted in complete resolution of signs and symptoms of the disease
Rescue of Neurological Development in Congenital Hypothyrodism: We Should Leave no Stone Unturned
No full textSyndromes of resistance to thyroid hormone action
No full textThyroid hormone (TH) action is crucial for the development of several tissues. A number of syndromes are associated with reduced responsiveness to thyroid hormones, expanding the original definition of thyroid hormone resistance, firstly described by Refetoff and collaborators in 1967, which is characterized by elevated circulating levels of T4 and T3 with measurable serum TSH concentrations, as a consequence of mutations of thyroid hormone receptor beta (TRβ). Recently, other forms of insensitivity to TH have been identified: defects in cell surface transporters such as the monocarboxylate transporter 8 (MCT8), genetic disorders of thyroid hormone metabolism due to alterations of selenoprotein synthesis, which comprise the deiodinase enzymes, and finally, mutations in the thyroid hormone receptor alpha (TRα). Since the syndromes of TH insensitivity are characterized by extremely variable clinical manifestations and different molecular mechanisms, this group of thyroid disorders has been very recently reclassified and a novel nomenclature proposed.
In this chapter, we will summarize the various phenotypes associated with these syndromes, with the exception of the inherited defects in thyroid hormone transporters such as the monocarboxylate transporter 8 (MCT-8), described elsewhere in this book
Thyroid hormone replacement in central hypothyroidism
No full textCentral hypothyroidism (CH) is a defect of thyroid hormone production due to an insufficient stimulation by thyrotropin (TSH) of an otherwise normal thyroid gland. Hypothyroidism is the most prevalent endocrine dysfunction, but CH is rare accounting for a small portion of hypothyroid patients. CH can affect patients of all ages with no sexual preference. The prevalence of CH can be estimated at 1:20,000 in the general population. Large tumors of the sella region represent the major cause of CH. Hypothyroid state is usually mild to moderate and manifestations are frequently masked by concomitant defects of other pituitary hormones. Treatment of CH takes advantage of thyroid hormone replacement. Nevertheless treatment cannot be is easily tuned as in primary hypothyroidism because the evaluation of circulating TSH levels has a very limited value in central defects
In this paper, various clinical and pathogenic aspects of central hypothyroidism are critically presented and discussed. A particular emphasis is given to tools and methods for an adequate treatment
Differential diagnosis between constitutional delay of growth and puberty, idiopathic growth hormone deficiency and congenital hypoogonadotropic hypogonadism: a clinical challenge for the pediatric endocrinologist
No full textINTRODUCTION: Differential diagnosis between constitutional delay of growth and puberty (CDGP), partial growth hormone deficiency (pGHD), and congenital hypogonadotropic hypogonadism (cHH) may be difficult. All these conditions usually present with poor growth in preor peri-pubertal age and they may recur within one familial setting, constituting a highly variable, but somehow common, spectrum of pubertal delay.
EVIDENCE ACQUISITION: Narrative review of the most relevant English papers published between 1981 and march 2020 using the following search terms “constitutional delay of growth and puberty”, “central hypogonadism”, “priming”, “growth hormone deficiency”, “pituitary”, “pituitary Magnetic Resonance Imaging”, with a special regard to the latest scientific acquisitions.
EVIDENCE SYNTHESIS: CDGP is by far the most prevalent entity in boys and recurs within families. pGHD is a rare, often idiopathic and transient condition, where hypostaturism presents more severely. Specificity of pGHD diagnosis is increased by priming children before growth hormone stimulation test (GHST); pituitary MRI and genetic analysis are recommended to personalize future follow-up. Diagnosing cHH may be obvious when anosmia and eunuchoid proportions concomitate. However, cHH can either overlap with pGHD in forms of multiple pituitary hormone deficiencies (MPHD) or syndromic conditions either with CDGP in family pedigrees, so endocrine workup and genetic investigations are necessary. The use of growth charts, bone age, predictors of adult height, primed GHST and low dose sex steroids (LDSS) treatment are recommended.
CONCLUSIONS: Only a step-by-step diagnostic process based on appropriate endocrine and genetic markers together with LDSS treatment can help achieving the correct diagnosis and optimizing outcomes
How zebrafish research has helped in understanding thyroid diseases [version 1; referees: 2 approved]
No full textNext-generation sequencing technologies have revolutionized the identification of disease-causing genes, accelerating the discovery of new mutations and new candidate genes for thyroid diseases. To face this flow of novel genetic information, it is important to have suitable animal models to study the mechanisms regulating thyroid development and thyroid hormone availability and activity. Zebrafish (Danio rerio), with its rapid external embryonic development, has been extensively used in developmental biology. To date, almost all of the components of the zebrafish thyroid axis have been characterized and are structurally and functionally comparable with those of higher vertebrates. The availability of transgenic fluorescent zebrafish lines allows the real-time analysis of thyroid organogenesis and its alterations. Transient morpholino-knockdown is a solution to silence the expression of a gene of interest and promptly obtain insights on its contribution during the development of the zebrafish thyroid axis. The recently available tools for targeted stable gene knockout have further increased the value of zebrafish to the study of thyroid disease. All of the reported zebrafish models can also be used to screen small compounds and to test new drugs and may allow the establishment of experimental proof of concept to plan subsequent clinical trials
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