TSH can be falsely decreased by medications including dexamethasone and corticosteroids. When possible, discontinue medications for several days or more prior to testing thyroid levels. Ideally, measure TSH in the morning (between 8 and 9am) and fast overnight (TSH levels are affected eating food high in fiber).
The researchers of the study "Clinical Significance of TSH Circadian Variability in Patients with Hypothyroidism" (Sviridonova MA, et. al.) found an average morning TSH level in the subclinically hypothyroid group was 5.83 mU/L and in the afternoon was 3.79 mU/L; 73% TSH circadian variability. Morning (8 - 9am), Afternoon (2 - 4pm).
In addition, I wanted to point out that TSH is a pituitary hormone that is totally inadequate as the primary diagnostic for thyroid issues. At best TSH is an indicator, to be considered along with more important indicators such as symptoms, and also levels of the biologically active thyroid hormones, Free T3 and Free T4 (not the same as Total T3 and T4).
A good thyroid doctor will treat a hypo patient clinically by testing and adjusting Free T3 and Free T4 as necessary to relieve symptoms, without being constrained by resultant TSH levels. You can get some good insight into clinical treatment from this letter written by a good thyroid doctor for patients that he sometimes consults with after initial tests and evaluation. The letter is then sent to the participating doctor of the patient to help guide treatment. In the letter, please note the statement, "the ultimate
criterion for dose adjustment must always be the clinical response of the patient."
Copyright 1994-2016MedHelp International.All rights reserved. MedHelp is a division of Aptus Health.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.