At the same time, it is one of the most overlooked preanalytical conditions that has to be actually known prior to testing. ![]() A patient’s sleeping status is one of the factors that can affect various laboratory results. The most commonly asked questions related to patient conditions are nutritional status (fasting/non-fasting), smoking, pregnancy, use of medications/supplements, consumption of alcohol and exercise ( 2). ![]() However, to manage the preanalytical phase successfully, all preanalytical factors related with the patient should also be thoroughly interrogated. It is considerably easier for laboratory managers to control factors belonging to the laboratory to prevent preanalytical errors. ![]() 6th ed.Preanalytical factors include conditions dependent on both laboratory and patient ( 1). Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. In: Rifai N, Horvath AR, Wittwer CT: eds. Freedman DB, Halsall D, Marshall WJ, Ellervik C: Thyroid disorders. Heil W, Ehrhardt V: Reference intervals for adults and children. Melmed S, Polonsky KS, Larsen PR, Kronenberg H: Williams Textbook of Endocrinology. Wilson JD, Foster DW, Kronenburg HM, Larsen PR: Williams Textbook of Endocrinology. Â Fatourechi V, Lankarani M, Schryver P, Vanness D, Hall-Long K, Klee G: Factors influencing clinical decisions to initiate thyroxine therapy for patients with mildly increased serum thyrotropin (5.1-10.0 mIU/L). Grimsey P, Frey N, Bendig G, et al: Population pharmacokinetics of exogenous biotin and the relationship between biotin serum levels and in vitro immunoassay interference. Saint Paul LP, Debruyne D, Bernard D, Mock DM, Defer GL: Pharmacokinetics and pharmacodynamics of MD1003 (high-dose biotin) in the treatment of progressive multiple sclerosis. Expert Opin Drug Metab Toxicol. Sick, hospitalized patients may have falsely low or transiently elevated TSH.ġ. Most individuals with primary hyperthyroidism have TSH suppression and do not respond to TRH stimulation with an increase in TSH over their basal value. Typically, the TSH response to TRH stimulation is exaggerated in cases of primary hypothyroidism, absent in secondary hypothyroidism, and delayed in tertiary hypothyroidism. Thyrotropin-releasing hormone (TRH) stimulation differentiates all types of hypothyroidism by observing the change in patient TSH levels in response to TRH. In primary hypothyroidism, TSH levels are significantly elevated, while in secondary and tertiary hypothyroidism, TSH levels are low or normal.Įlevated or low TSH in the context of normal free thyroxine is often referred to as subclinical hypo- or hyperthyroidism, respectively. It is especially useful in the differential diagnosis of primary (thyroid) from secondary (pituitary) and tertiary (hypothalamus) hypothyroidism. The ability to quantitate circulating levels of TSH is important in evaluating thyroid function. In primary hyperthyroidism, TSH levels will be low. In primary hypothyroidism, thyrotropin (TSH, formerly thyroid-stimulating hormone) levels will be elevated. See Thyroid Function Ordering Algorithm in Special Instructions. When hypothalamic-pituitary function is normal, a log/linear inverse relationship between serum TSH and free thyroxine exists. This biological variation does not influence the interpretation of the test result since most clinical TSH measurements are performed on ambulatory patients between 8 a.m. Serum TSH concentrations exhibit a diurnal variation with the peak occurring during the night and the nadir occurring between 10 a.m. Second, it stimulates the thyroid gland to synthesize and secrete triiodothyronine and thyroxine. First, it stimulates cell reproduction and hypertrophy. ![]() TSH interacts with specific cell receptors on the thyroid cell surface and gives rise to 2 main actions. Additionally, the hypothalamic tripeptide, thyrotropin-releasing hormone, directly stimulates TSH production. TSH is synthesized and secreted by the anterior pituitary in response to a negative feedback mechanism involving concentrations of free triiodothyronine and free thyroxine. The beta subunit is different from those of the other glycoprotein hormones and confers its biochemical specificity. The alpha subunit is similar to those of follicle-stimulating hormone, human chorionic gonadotropin, and luteinizing hormone. Thyrotropin (TSH, formerly thyroid-stimulating hormone) is a glycoprotein hormone consisting of 2 subunits.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |