Informational Posts

What You Need To Know About Doing Thyroid Blood Tests

What You Need To Know About Doing Thyroid Blood Tests
Originally published on 30th May 2017
Last updated on 1st December 2023

Common questions about thyroid blood tests for those with medical conditions such as a thyroid disorder include:

  • Do I take my thyroid medication as normal before the blood draw?
  • Do you need to fast for thyroid blood work?
  • How often should it be done?
  • Does it need to be in the morning?
  • Can it be done in the afternoon?
  • Is fasting required for a TSH test?
  • Can I have a thyroid blood test on my period?
  • What should be tested?

A Thyroid Blood Testing Kit

Probably the most important thing to be aware of as someone with a thyroid condition, is whether you should take your thyroid medication before or after having any testing done.

When To Take Medication

T4-Only Meds

In regards to T4-only medication such as Levothyroxine and Synthroid, they only have a half-life of around five to nine days, which means that once you’ve become stable on a dose, it takes around a week for half of that dose to clear the body and blood levels to reflect this. This is why, when some people decide to stop taking it, they feel fine for the first week or so.

Therefore, whether you take T4-only medication right before your blood test or blood sample is taken, or haven’t taken it for up to two days beforehand, your TSH levels and Free T3 levels should still be the same, but free T4 may well show a peak two hours after taking T4 medications.

According to

“Serum T4 (Free T4) concentrations peak two to four hours after an oral dose and remain above normal for approximately six hours in patients receiving daily replacement therapy.” For this reason, thyroid expert Richard Shames, MD has the following recommendation: “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.”

The American Association of Clinical Endocrinologists (AACE) and The American Thyroid Association (ATA) Guidelines also state:

“In monitoring patients with hypothyroidism on L-thyroxine replacement, blood for assessment of serum free T4 should be collected before dosing because the level will be transiently increased by up to 20% after L-thyroxine administration. In one small study of athyreotic patients, serum total T4 levels increased above baseline by 1 hour and peaked at 2.5 hours, while serum free T4 levels peaked at 3.5 hours and remained higher than baseline for 9 hours.” [1]

So if you were to take your T4-only thyroid medication before a thyroid blood draw, your Free T4 levels could come out elevated, leading to your doctor lowering the medication dosage, when you don’t actually need it lowering.

However, in most cases, taking T4-only medication the morning of your test will not be an issue, as most doctors tend to adjust dosages according to TSH only, which shouldn’t be affected (although this is ideal. It should be adjusted based on the Free T3 and T4 levels too). But to get a reading of your Free T4 level that is reflective of most of the day (and something your doctor should also be testing, alongside TSH) you will need to hold fire on taking your medication until after the lab test.

T3 Meds

If you’re taking a thyroid medication that contains T3, such as NDT or T3 synthetic Liothyronine, it’s important to be aware that T3 has a half-life of around eighteen hours.

Straight after taking a T3 containing medication, the TSH level begins to fall and then stays suppressed for as long as five hours. Free T3 levels also increase after taking T3 medication and hit a peak after two and a half hours. [2]

Dr. Bianco, a thyroid doctor and scientist, reports in his book that after taking a tablet containing T3, it is rapidly absorbed into circulation, with a spike showing after 2-3 hours. He says that T3 can increase by as much as 50% after taking it. T3 returns to baseline levels around 20 hours after the dose.

This means that if you were to take your T3 containing thyroid medication before thyroid tests are done, your test results may imply that you are overmedicated when you are not, or even that your levels are within range or optimal, when you’re actually under-medicated. So it can affect your ability to get an accurate result and adjust your dosage accurately.

Therefore, you’re best to hold off taking this medication until after the blood draw. I take my thyroid medication with me so that I can take it straight after the blood test, otherwise I start to feel unwell by midday.

The bottom line is: you’ll get a more accurate result if you take any thyroid medications after the blood test. 

Klikkit Buttons Reminding Rachel to Take Supplements


If you’re also one of the thyroid patients who take the supplement biotin, it is also worth knowing that it can cause falsely elevated thyroid levels on test results, making you look overmedicated or hyperthyroid when you’re not. Therefore, it is advised to not take it for at least 48-hours before a thyroid blood test.

Should I Fast for a Thyroid Test?

Do I have to fast for TSH blood work? Do thyroid blood tests require fasting?

In terms of fasting, most doctors tell thyroid patients that it’s not necessary to fast before a blood test. However, researchers have found that after eating, our TSH level becomes suppressed. [2]

This means that a high TSH could instead look much lower after eating, and borderline levels no longer borderline. As so many doctors use the TSH level to decide if a patient is adequately treated, or in need of more or less thyroid medication, this could result in patients having their thyroid medication wrongly altered, or even being told that their ‘borderline’ hypothyroidism is now ‘normal’, resulting in some thyroid patients being inadequately treated for their thyroid condition.  All because they ate before their test.

Therefore, your TSH level is likely to be at its highest and most reflective of its underlying status, when tested after fasting, in the early morning. 

Timing Matters 

Another thing to keep in mind is the time at which your blood is drawn for thyroid testing.

Each time you have your thyroid tests done, you should aim for it to always be done at the same time, and under the same circumstances (i.e. fasting), so they’re as accurate and comparable as possible.

Given that you shouldn’t take your medication until after the draw, as early as possible in the morning and before 9am is preferable. This is because thyroid hormone levels have a circadian rhythm with a peak at night. Dr. Geracioti suggests that blood tests for hypothyroidism be done before 9am in order to not miss subclinical hypothyroidism and have as accurate results as possible. [4]

Does Being Ill Affect The Test?

Being unwell could affect test results temporarily. Sometimes, infections or a bout of an inflammatory condition can alter results until the illness resolves, so if you receive an unexpected result when unwell, it is probably wise to retest after you’ve recovered to rule it out.

Also, as diarrhoea can interfere with the absorption of your thyroid medication, this could affect your thyroid hormone levels and any testing.

Does Menstruation Affect Testing?

If you’re feeling particularly unwell from your period then you may wish to have blood drawn when you feel better. Especially if you already lose a lot of blood with menstruation. Heavy periods can be a symptom of hypothyroidism.

Thyroid expert, Dr. Alan Christianson, says that being on your menstrual cycle may change your thyroid levels, and that if you test in the middle of your cycle, you will not get the same results as at the beginning of your cycle. He suggests testing between days 1-9 of your cycle (day one being the first day of menstrual flow), or days 21-28, but not on days 10-20 of your cycle. [5]

If your periods are irregular, you can wait until the first week that they begin.

How Often?

In terms of how often you should be having your thyroid tests conducted, once every six to twelve months is standard if your levels are optimal and you feel well. Every two months is more common if you’re still adjusting dosage and having symptoms.

Many patients need their dosage altering as the weather gets colder, and again when it warms up, to reflect an increase or decrease in demand for thyroid hormone, due to external temperatures.

When first starting thyroid medication for hypothyroidism, most doctors recommend testing thyroid levels again about four to six weeks after the start of the treatment, to determine if the dose of medication is correct, but waiting eight weeks can allow the medication to finish building in the body and supply a more accurate reading.

When your thyroid gland isn’t working properly, thus leading to hypothyroidism, it’s incredibly important to correct the low levels of thyroid hormone with frequent and thorough testing.

What Should Be Tested?

A full thyroid panel (also known as a thyroid function test) is required to obtain the most comprehensive and accurate look at how you’re doing, as TSH alone and even TSH and Free T4 test without the other components of the thyroid panel, don’t give the full picture.

Free T3 and Thyroid Antibodies TpoAB and TgAB are important to monitor too. Many thyroid patients find that whilst their TSH is OK, their Free T3 and Free T4 are not optimal and so they still feel unwell. If your doctor won’t order the full thyroid panel, do know that it is relatively inexpensive and simple to order these tests yourself. Thyroid patients can order them from here and here.

TSH serves as an average read out over the previous four to six weeks of your thyroid levels but doesn’t give the most comprehensive view.

Do you follow these tips when you have blood drawn?

Be Your Own Thyroid Advocate Book CoverSee also:

The book Be Your Own Thyroid Advocate: When You’re Sick and Tired of Being Sick and Tiredwhich builds on this article in detail and explains how to thrive with thyroid disease.

You can click on the hyperlinks in the above article to learn more and see references to information given, as well as the below links.







About Author

Rachel Hill is the highly ranked and multi-award winning thyroid patient advocate, writer, speaker and author behind The Invisible Hypothyroidism. Her thyroid advocacy work includes writing articles, authoring books, producing her Thyroid Family email newsletters and speaking on podcasts and at events about the many aspects thyroid disease affects and how to overcome these. She is well-recognised as a crucial and influential contributor to the thyroid community and has a large social media presence. Her bestselling books include "Be Your Own Thyroid Advocate" and "You, Me and Hypothyroidism".


  • Nancy
    January 25, 2024 at 2:11 am

    I am still trying to find if i am hypo and have Hashi. Some say blood tests dont do justice need to see endocrinologist. I am so confused. My issues are constipation, hair loss thinning, weight gain, and sleep issues. What are your recommendations? Thanks

  • Sol
    December 8, 2021 at 2:26 am

    Sad stories. Really, does the medical industry stand to gain by actually healing and curing people-by treating them appropriately so they function well? No. And so few people see this. They stand to lose immense amounts of money and power if we get well, so talk about a conflict of interest! I’m still researching, but my mind really just won’t work any longer to absorb the information. I’ve been fighting the thyroid battle for decades. I had to pitch a fit in a doctor’s office just to get her to consider my thyroid when all she wanted to do was get me to “exercise” and “see a counselor”. They love referring you to counselors when you have thyroid related depression. Finally my doc found a lump on my thyroid that was precancerous. Over half my thyroid was removed and I’ve had ups and downs since, but now its just going downhill and I don’t have the presence of mind to fight it anymore. You shouldn’t have to do all your own research, work to get a doctor to even listen to you, and still go around undertreated, ignored and mistreated while these quacks still get paid. What profession can completely fail you or make you worse, and still get paid? The medical profession, of course! Hoping all the best for you out there. God bless.

    • Donna
      August 24, 2023 at 4:47 am

      Oh, how I feel for you. I’m pretty much in the same predicament. The Doctor is constantly doing thyroid tests and has decided that I need to take 125 MCG’S of thyroid and after a few weeks we’ll check it again. My thyroid has been DEAD for Years! It is now 2023! My Doctor told me I had a really REALLY HIGH NUMBER! So, here we go again! I’m so frustrated with all of this, and just can’t seem to get even an endocrinologist to figure out what will help me. Yes, I feel alone and un treated! I hate this.

  • Norma Ojeda
    January 26, 2021 at 2:53 am

    You amaze me, I agree, not all doctors are caring & dedicated to their medical oath. I wish you continued strength & endurance, you inspire me.

  • Josephine Hartline
    April 17, 2020 at 1:00 pm

    I took my cytomel 5 about 6 hours before my test. how bad will results be messed up?

  • Alexa
    June 3, 2019 at 8:26 pm

    I must voice my admiration for your kindness supporting people that absolutely need help with this particular situation.

  • Mike
    May 9, 2019 at 2:54 pm

    I retired from the military on 1 January 1997 after over 20 years of faithful service to my country during 3 war periods (2 at the same time), several skirmishes and 2 deployments to hostile territories starting with the Viet Nam War. Just prior to retirement, the last 6 months, a person is authorized to take advantage of a benefit to ensure a whole person, in good shape – as close to original enlistment shape as possible, is released back onto the ‘economy’. The benefit is to go to the hospital and get an aggressive physical to ensure all health issues are resolved before departure back into the civilian world. It is also known as the ‘exit physical’. I received dental work, lab tests, EKG and the like. In late January I also went to the Optometry clinic for a current evaluation of my sight. When interviewed by the doctor initially he asked, “Have there been any changes in your sight since your last exam?” I stated, “Yes, I am having extreme difficulty seeing out of my right eye and my left one doesn’t seem very useful either.” He examined me and discovered that I was nearly legally blind.

    A normal appointment in the eye clinic was for 20 minutes. Mine lasted one hour due to the doctor not being able to adjust my vision with machinery. He performed a color vision test and I failed miserably. The circles with hidden numbers looked like grey circles to me. He then grabbed the little bottle of medicated eye drops with the red cap on it and asked me to cover my right eye and he showed me it and asked how red it was on a scale from one to ten with my left eye. I said, “I guess 10”. He then asked me to cover my left eye and asked the same for the right eye and I said, “1”. He asked me to sit outside his office in the hallway while he made a phone call. I overheard him (not eves dropping because he was yelling) talking with Fitzsimons Army Medical Center’s Neuro-Ophthalmology Clinic. He said, “You don’t understand. This is an emergency. This gentleman is retiring in less than 6 months and needs to be seen tomorrow. I don’t care if he has to be seen after-hours! Yes, 5:30 pm is excellent.” He then called me back into his office and gave me my appointment for the next day with an understanding that I was to keep him informed and ‘in the loop’. I thanked him and went on my way somewhat shocked.

    At the Neuro-Ophthalmology clinic the next evening at the Fitzsimons Army Post in Aurora, CO I was put through a grueling series of tests for 3 hours. She finally stated, “I have exhausted all known tests available at this time so I am requesting an MRI be done of your whole head to determine if you may have something going on inside that we cannot see.” She told me that she had requested it ‘stat’ so it must be done A.S.A.P. and what to expect from the MRI lab. I departed homeward (From Denver to Cheyenne, WY where I was stationed at F.E. Warren AFB).

    I received a phone call, at work, the following day asking that I report on the following Wednesday (5 days away) for an exam at the Fitzsimons Army Post MRI lab. My appointment was for 10:30 am but was pushed back to 1 pm due to emergencies. The MRI took 2 hours because the doctor requested extremely thin slices so as to be able to see the smallest tumor possibly on/in my optic nerve. Exhausted, I went to a fancy restaurant to enjoy a great Mexican meal at Garcia’s Mexican Restaurante in Denver, Colorado. I was born and raised in Phoenix, AZ where this franchise originated and I had met the original start-up adult owners – immigrants – when I was a kid. When I returned home my wife said that they had been trying to reach me so I attempted to call but, due to the late hour, they were closed.

    At my workplace the next day I received a phone call from my Neuro-Ophthalmologist and she stated, “I don’t like to do this on the phone but, you have a very large tumor growing in your Pituitary Gland and it is crushing your optic nerve.” She warned me to be careful while driving and so forth. She also asked that I see her the next day so she could “go over the details”. She showed me the ‘slides’ of my MRI and explained as best she could. Then she said that I needed to have neuro-surgery “to get it out”. She said she had contacted a neuro-surgeon and he wanted to see me right away.

    At the neuro-surgeon appointment with Major Dr. James Ecklund he told me that I needed to have an extensive exam before the surgery so that its’ success was surer. I asked how long before this procedure and he stated that it was an “emergency” and that it must be done, “As soon as possible.” I asked a multitude of questions including details of the surgery and the ‘what ifs’. I asked, “What if it wasn’t found.” He stated, “We may have found you slumped at your desk…dead from a massive stroke, before your retirement in 5 months…that soon.” He told me the surgery would be about 4 hours long maybe a little longer. I asked if I could harvest my own blood for the surgery but he explained that he did not want me depleted prior to the surgery. He referred me to an Endocrinologist for hormone evaluation due to the tumor growing out of my pituitary gland and that it might be affecting my hormone system. They did an extensive survey of my hormone system before surgery. He also sent me to the ‘Ear, Nose and Throat’ clinic because they had to start the surgery to give the neuro-surgeon access to perform his surgery. They also closed me up after the neuro-surgeon was finished and fixed my severely deviated septum during the process. I jokingly asked them if they could give me a “Burt Reynolds Nose’ on the way out and they all laughed and jokingly stated that I did not have enough rank for that.

    The surgery was on Friday March 15, 1996 and lasted 7 1/2 hours due to complications. They went through my nose to get the tumor. The wound was all the way to the center of my head.

    In recovery the neuro-surgeon said the reason it took so long was that they had to stop and “save your life for 45 minutes” because I had started bleeding profusely during the procedure and needed 2 ½ pints of whole blood. That and that the tumor was not of the normal consistency so was more difficult to excise. It was harder than expected and had to be ‘whittled’ out small pieces at a time. They couldn’t get it all due to the tumor having broken through the left wall of the sphenoid sella and was surrounding the left side carotid artery and nearly squeezing it off. They did not want to accidentally cut that artery because I could bleed to death and they would not be able to stop it.

    Good news and bad news. “The surgery was a success!” The bad news, “We couldn’t get it all so you must have Radiation treatments to eradicate the residual tumor.” Great news was I had regained my vision. Now I know what it is like to nearly go blind and get my sight back.

    I was placed on permanent Convalescent Leave status until all avenues of care had been exhausted. I traveled the country by means of the ‘Red Cross Bird’ (Medical travel by Air Force plane to other medical facilities in California and Texas picking up and dropping off passengers in several states to include Nebraska, the Dakotas, Montana, Idaho, Utah, Washington, Oregon, Arizona and New Mexico – basically, the western states) to be screened for possible radiation treatments and Endocrinology evaluation due to the closure of Fitzsimons AMC on June 1st, 1996.

    I was told by the oncologists at Travis AFB that they could do it. I asked how it would be done and he explained, “We hold a ray gun to your head and zap you for about 4 weeks daily.” I questioned results and damage. He stated, “We will destroy anything in the ray gun’s path including memory, optic nerve, ear organs and anything else in the way. You will be a blind vegetable when we are finished but you will be alive and no guarantee of eradicating the residual tumor.” I declined their help respectfully and requested a second opinion.

    I was flown to San Antonio, TX to be seen at Wilford Hall Medical Center at Lackland AFB, TX by the Oncology Clinic. They told me they had the most ‘up-to-date’ equipment and that they would try to miss all the important stuff and “Just get the tumor.” They scheduled me for an MRI and CT and a ‘set-up’ appointment. At this appointment 2 weeks later I was measured and a mouth piece form was taken along with the MRI and CT scan and an appointment for a 6 week course of radiation treatments in August and September.

    I became very ill from the treatment. My head swelled up due to the bombardment of the radiation particles. I suffered pain throughout my whole body especially my head, neck and back. I have a video of a treatment session if you are interested that would make things a lot clearer of what I went through during those treatments.

    At Travis AFB, CA I was put on 175mcg of Synthroid and also testosterone shots every 2 weeks for replacement treatment of deficient hormones by the Endocrinology Clinic doctor (a full bird navy Colonel/Captain) due to damage to the pituitary gland. This was before the radiation treatments began in August of 1996 for 6 weeks. I was warned by the endocrinologist that my medical care was going to be very critical and stressed that I needed to be followed by a credible endocrinologist for the rest of my life. He said that my labs were never going to be normal again and that any doctor(s) I see must be keen to recognize physical symptoms to effectively treat me. He said that I had the constitution of a 90 year old man and that a severe imbalance would be very detrimental to my survival. He also said that I needed to be reevaluated periodically for changes to my hormone medication.

    I retired as an E-6 and could not make E-7 due to the blindness making it impossible to see the questions on the promotion test.

    My future was shattered by severe medical problems and I could no longer be employed. It was very depressing. The military didn’t want me anymore because I was too high maintenance and not deploy-able. I couldn’t even be stationed overseas.

    I came out of the military with a severe head wound (very painful) and complications related to severe hypopituitarism. I do not have a functioning pituitary gland so it is as if I have no endocrine glands because the feedback mechanism is broken and cannot be fixed. Proper levels of replacement hormones are a must for a good quality of life and a comfortable one at that.
    (C) 2017

    I hope this helps some of you people.

    My hero was the optometrist. If it weren’t for his knowledge of his job I would have died before retirement at age 40. I am 63 now and very high maintenance. Life is very difficult for me . . . due to ignorant and incompetent doctors.

    I hope this is published. I do not mean to intrude and definitely do not want to demean anyone.
    Let’s live life more comfortably is what I say.

    Keep up the good fight Ms Rachel Hill. Do you know of Mary Shomon in the USA? She is a thyroid activist in the USA.

  • Mike
    May 9, 2019 at 2:38 pm

    Point Paper – Thyroid

    The thyroid gland remains one of humanities strangest mysteries. The thyroid gland manages the whole body’s system to do many things. The most important is metabolism. Most of the doctors today are not correctly assessing patient’s status of metabolism.

    The metabolism is the most misunderstood. It is the efficiency of the body. It keeps you breathing, your heart beating correctly and numerous other functions. If your body’s metabolism slows down then your body is much less efficient and will suffer the consequences. You may have such symptoms as hoarse voice, coarse hair, weight gain, cold hands, cold feet (both hands and feet feel hot all the time in warmer climates and cold as ice in cooler climates), dryness and scaling of the skin especially the hands and feet that may crack open and bleed, tiredness, fatigue, lethargy, lack of enthusiasm, sleep too much, loss of appetite, brittle nails, half eyebrows, skin sores mostly of the feet and hands and lower extremities from the elbows and knees outward, muscle weakness, constipation, abdominal distress, painful stiffness and swelling of the joints, depression, slowed healing of sores or wounds, slowed heart rate, impaired memory, low body temperature, foul body odor, aggressiveness and thinning hair. The organs in your body will not run efficiently as a result of low thyroid or as it is scientifically called – hypothyroidism.

    The efficiency of metabolism is based on the amount of Triiodothyronine also known for its short designation as T3. It affects every physiological process in the body, including growth and development, metabolism, body temperature and cellular tissue maintenance to include skin and even your heart rate.

    The monitoring of the levels of T3 in the body is the responsibility of the Hypothalamus. The hypothalamus tells the pituitary gland that the body needs more T4 produced by the thyroid gland so that the T4 can be converted to the active T3 the body uses to repair and maintain itself.

    When a person is on Levothyroxine also known as T4, brand named Synthroid, then only the Total T3 and Free T3 need be monitored. It is the T3 that does all the work in the body. That is why the thyroid gland produces so much T4 so as to have ample supply for conversion to T3.

    T4 is converted by the liver into T3 for use by the body’s metabolic system to maintain and refresh the tissues and cells throughout the body. A liver function test may be necessary.

    When a patient takes T4 in the form of Synthroid it is absorbed into the bloodstream and converted to T3 by the liver. Not all of the medication is absorbed or converted by the liver so the monitoring of T3 is critical to obtain an efficient level of T3 available to the metabolic system. Since the T4 is consumed by the body through medication it is foreign to the body, in other words the body did not produce it so the body may reject it or some of it. So, an adequate replacement amount needs to be administered in order for your body to get enough of T4 to convert to T3 to satisfy the need of the body.

    When patients are on high doses of Levothyroxine only the Total T3 and Free T3 need be monitored. Those are the targets of replacement L-Thyroxine in the form of Synthroid medication, also known as ‘replacement T4’.

    Without a functioning thyroid gland the patient is in danger of a much reduced metabolic rate and will suffer the ill effects of such. They may even die due to not enough T3 to sustain life.

    So, T3 is the workhorse of the body.

    WARNING – to those who eat shellfish and/or seaweed. If you are on replacement or supplemental thyroid medication then you must avoid these types of food. Using Kelp or other seaweed to help with a thyroid issue such as weight loss may cause fainting spells and/ or seizures. It can throw a person into hyperthyroidism.

    Medication dosages:
    25mcg, 50mcg, 75mcg, 88mcg, 100mcg, 112mcg, 125mcg, 137mcg, 150mcg, 162mcg (112mcg and 50mcg taken together), 175mcg, 188mcg (100mcg and 88mcg taken together), 200mcg, 212mcg (112mcg and 100mcg taken together), 225mcg (200mcg and 25mcg taken together), 237mcg (125mcg and 112mcg taken together), 250mcg (200mcg and 50mcg taken together), 262mcg (150mcg and 112mcg taken together), 275mcg (200mcg and 75mcg taken together), 288mcg (200mcg and 88mcg taken together), 300mcg, 312mcg (200mcg and 112mcg taken together), 325mcg (300mcg and 25mcg taken together), 337mcg (200mcg and 137mcg taken together), 350mcg (300mcg and 50mcg taken together), 362mcg (200mcg, 112mcg and 50 mcg taken together), 375mcg (300mcg and 75mcg taken together), 388mcg (300mcg and 88mcg taken together), 400mcg (300mcg and 100mcg or 2 -200mcg taken together), 412mcg (300mcg and 112mcg taken together)

    CAUTION – Raising and lowering this medication MUST be limited to 13mcg maximum or it may cause harm to patient. When changing dose allow 8 weeks for full absorption and leveling in the body’s system before labs are drawn to check level.
    (C) 2019
    Written by Michael J. Valenta
    903 Pike Street
    Cheyenne, WY 82009 (USA)

    I wrote this to teach doctors, especially endocrinologists, what they are doing wrong. It is not all inclusive. This ‘point paper’ targets medication dosing and how to evaluate proper Triiodothyronine levels while ensuring the most accurate levels are seen to help determine proper dosing of medication. I am not a doctor but a patient who was nearly killed by incompetent doctors and especially . . . endocrinologists who should not be practicing medicine but digging ditches instead.

    I hope it helps to save lives and make people more comfortable . . . being alive.

    I am not doing this to gain fame and fortune. I just want to help my fellow humans.

    • Tricia Clark
      March 27, 2024 at 7:42 pm

      Thanks for this information.. The timing and fasting are so vital as I take t3 & t4. I thank God for you as none of it was given by my gp nor amazingly my endocrinologist!

  • Mike
    May 7, 2019 at 4:04 pm

    When On T4 replacement medication (Levothyroxine or Synthroid) it is FACT that the draw MUST be in the morning at the same time the medication is normally taken or as close as possible to BUT the medication MUST NOT be taken that morning until AFTER the blood has been drawn (take the medication with you). This reveals the ‘trough’ level in the body. Taking the medication before a blood draw will invalidate the results. They will always be higher than they should be. Every body is different so the trough level is the most accurate for this medication.

    The most accurate tests are, when on the medication, Total T3 and Free T3. Why, because the T3 is what the body uses NOT T4!!!!! Your body produces large amounts of T4 and converts it to T3 in the liver for use by your metabolism to repair and help your body do its normal functions. Exerting yourself while on replacement T4 causes fatigue easily because the body is not producing enough T4 and T3 naturally for the extra effort.

    When taking replacement T4 the body did not produce it so the body may reject it or not absorb it fully therefore some people need higher doses of replacement T4 than others regardless of the test ranges. Doctors need to look at the physical symptoms in order to make a better decision.

    After an increase or decrease the blood draw must wait 8 weeks in order for the medication to stabilize in the body – also known as ‘leveling off’.

    I hope this information is helpful. I have been victimized by EXTREMELY INCOMPETENT doctors out there!!!!! Endocrinologists too! They have nearly KILLED me several times!!!

    • Irene Ritchie
      September 28, 2021 at 4:56 pm

      Thank you for taking the time to explain thyroid fundamentals. You are very helpful. I am a pituitary patient as well. This is useful information to pass on to internists and endos.

  • Karen Taylor-Brown
    March 25, 2019 at 10:18 am

    Hi Rachel
    I’ve been on Levo for 15+ yrs with no change in my symptoms in all that time, & also no stability in my TSH results either. I’ve lost everything, my home, my career, family members, the lot! I’m now sadly forced to live on benefits after working full time for almost 30yrs in a corporate environment.
    I finally got to see an Endocrinologist last week & he categorically told he WILL NOT under any circumstance prescribe me NDT, which is what I’d requested to try, firstly via my GP, where I got no joy whatsoever, & who also refuses to do full Thyroid blood tests. I struggled to get a private blood test done in 2017, due to the costs, where it showed my TSH was high @ 6.8 along with my TPO-AB off the charts >1,000
    May I please ask you where do you get your blood test done & how often & at what cost? Would you also point me in the right direction, so that I can possibly look at buying my own NDT… if I can afford it.
    Thank you

    • Rachel Hill
      March 26, 2019 at 1:13 pm

      Hi Karen, so sorry to hear about the devastating effects hypothyroidism has had on your life. Unfortunately, I hear way too often how Levo leaves many of us unwell still. I experienced it myself too.

      I order my blood tests usually through Medichecks: My GP tests TSH, FT3, FT4 and antibodies TpoAb and TgAb every 6 months but I order additional tests through Medichecks if I feel I could benefit from testing sooner (i.e. if I feel unwell).

      For liability reasons, I cannot give sources of over the counter thyroid medication such as NDT, but you could speak to other thyroid patients in online groups and forums.

  • michele stoerr
    February 15, 2019 at 12:47 am

    when should i do the test.
    I take every day at 7am,75 mcg of tirosint plus a quarter of a grain of armour,then at 2pm an other quarter.

    • Rachel Hill
      February 15, 2019 at 8:55 am

      Hi Michele, please see info above in the article.

  • Gillian
    July 25, 2018 at 6:34 am

    This blog is truly awesome.

    • Rachel Hill
      July 25, 2018 at 11:33 am

      Thank you! So glad you like it!

  • Angelia
    May 24, 2018 at 4:01 am

    Thankful to my father who told me about this site. Lots of useful information for my thyroid condition.

  • Mary Huber
    March 7, 2018 at 6:38 pm

    I have recently changed from Canadian ERFA “natural” thyroid sold as “the Armour thyroid that FOREST LABS MANUFACTURED. I have been battling many illnesses in the last few years. I have changed to Thyrovanz.. I am wondering if this product has the actual RAW T3 ? IF NOT it is just more fake advertising. I need the T3!! Where can I safely purchase a product with natural T3 if Thurman turns out to be unreliable?


Leave a Reply