What is the optimal time of day to have your thyroid levels tested?
Tests, tests and more tests! Sometimes I think I have test anxiety when it comes to thyroid hormone level testing. Ever wonder what time of day you should have your child’s thyroid levels tested? Well, I have!
I asked our pediatric endocrinologist whether we should give our kids their Synthroid (Levothyroxine, etc.) on the mornings that we are going for blood draws or wait until after the draw to administer the medication and whether we should go in the morning or the afternoon. Our doctor said there are schools of thought that believe there could be an issue with getting an accurate picture of the thyroid hormone levels if the draw is performed within an hour of administering thyroid hormone replacements. This runs counter, though, to the idea that Synthroid maintains a constant level of thyroid hormones in your body. So – the question remains – what time of day should you have thyroid tests done and should you dose prior to the draw?
There are articles and research on the topic – unfortunately I could not find any research on optimum test times and conditions for children with hypothyroidism – but the information I found is helpful and worth printing out and discussing with your pediatric endocrinologist. If you are an adult with hypothyroidism or have symptoms of hypothyroidism, you will want to read this as well.
In Mary Shomon’s article, Optimum Times and Conditions for Thyroid Blood Test, she quotes Dr. Richard Shames as saying: “I absolutely recommend that patients have any morning blood tests evaluating the thyroid before taking any thyroid medication. I have always told my patients to do it this way.”
Tina Kaczor, ND, FABNO, writes in her article, Thyroid-stimulating Hormone Fluctuates With Time of Day, about a study in which thyroid hormone levels were assessed in the morning (8am-9am) and afternoon (2pm-4pm) for each participant. She states that: “This study implies that it is best for patients to have their blood drawn in the morning.”
To avoid the potential for inaccurate or skewed results from dosing in the morning and then visiting the lab and to avoid skipping the dose, visiting the lab and then potentially forgetting to give the meds when we get home, we have been having the kids’ labs drawn in the afternoon (after having taken their meds early in the morning as usual). My husband and I go whenever we can get an appointment for our labs, without much regard to time of day. After reading this information, I feel that we should re-visit the topic with the kids’ pediatric endocrinologist and with our endocrinologists. The research seems to indicate that the most accurate results are produced in the mornings prior to administering Synthroid. The tough part for parents of children with congenital hypothyroidism is balancing this with the need to visit the lab at a good time for your child (avoiding nap, getting the phlebotomist that you want, not missing school, etc.).
Readers, please share what you have been told or heard about the best times and conditions for testing thyroid hormone levels.
By Blythe Clifford aka Thyroid Mom
