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Can thyroid function tests be done while fasting?

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Posted on Wed, 30 Jul 2014
Question: I have another question for Dr. XXXXXXX I went to my Cardiologist/Internist today. He put me on Lasix, gave me a few supplements, and a Saliva test to take. He is working, to find the cause of my water retention. He said my thyroid levels were normal, but I forgot to get the numbers. I have a prescription for another Thyroid Level test, from my primary care doctor. She is the one who writes me the prescriptions for Armour Thyroid. Can you please tell me, if this blood test should be taken while fasting? My Cardilogist/Internist does NO blood testing while fasting.
doctor
Answered by Dr. Binu Parameswaran Pillai (18 hours later)
Brief Answer:
Hi

Detailed Answer:
Hello,
Good day and Welcome back
Sorry for the delay in reply. I was away in the country side today.

Glad to know that the thyroid function tests was normal.
The thyroid function tests will be bette if done in the morning before taking the medicine or 4 hours after taking the medicine. But if you are doing only TSH, it can be done anytime. TSH levels tend to be little on higher side by late evening and i advice my patients to get the TSH done before 5 pm.

I guess the saliva test your cardilogist want is "midnight salivary cortisol"

Regards
Binu
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Follow up: Dr. Binu Parameswaran Pillai (6 hours later)
Hi Dr. XXXXXXX no problem, at all for the delay. I do know, not to take my thyroid medication, in the morning, before getting my blood taken. I was just wondering, if the test should be done on an empty stomach, or for example, can I eat a light breakfast before the blood test.Also, the Saliva test he gave me, to take, is for 4 times, in one day, at 4 hour intervals.
doctor
Answered by Dr. Binu Parameswaran Pillai (2 hours later)
Brief Answer:
No need of fasting for thyroid test

Detailed Answer:
Hello,
You can take light breakfast before Thyroid blood test. That is not a problem.
But of course, if you also doing other tests like fasting blood glucose or lipids, it has to be a fasting sample.

I guess the saliva test is a cortisol test.

Binu
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Binu Parameswaran Pillai (19 hours later)
Thank you so much Dr XXXXXXX I have 1 more questions, them I won't bother you until I have blood tests in front of me.

The first one concerns melatonin. I heard if you have thyroid disease you should not take it because it's a hormone. Is that true?

The second question, is it helpful or harmful to supplement with nutrients such as kelp. I have read conflicting information about this.
doctor
Answered by Dr. Binu Parameswaran Pillai (1 hour later)
Brief Answer:
Hi

Detailed Answer:
No worries. It is a pleasure to answer queries.

I do agree that if you search internet, you may get conflicting results . As far as health information is concerened, please trust information only from FDA, XXXXXXX Thyroid association, British Thyroid association or similar authorities. There are information for general public in theoe websites. Many naturopathy sites also can be misleading and confusing.

Melatonin does have inhibitory action on thyroid gland. It may also interfere with thyroid hormones. However, small doses for insomnia for a brief period would not cause major problems. Please go through the following website from mayo clinic.

http://www.mayoclinic.org/drugs-supplements/melatonin/safety/hrb-0000


Regarding Kelp, it has iodine content and may cause hyperthyroidism. However, since your thyroid is dyfunctional, it doesnt really matter much. ( because, your thyroid gland probably is not capable to trap and process iodine now due to aut immune destruction). Please go through following website from british thyroid association. It is really helpful.

http://www.btf-thyroid.org/index.php/thyroid/fables

I hope i have answered your question. Once the thyroid gland is destroyed by auto immunity, hypothyroidism develops. After the complete destruction of the gland, hardly any hormone is secreted from it and diet supplements may not really help further to regenerate the gland ( despite numerous claims from naturopathy websites).

Regards
Binu
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Follow up: Dr. Binu Parameswaran Pillai (26 minutes later)
Thank you again, Dr. XXXXXXX I will definitely check out the websites you are telling me about. I thought I was finished asking you questions, but I have one more and that is: Will my body eventually totally destroy my thyroid? Is this something that normally happens to patients with Hashimoto's disease? As I think I already mentioned, I was diagnosed about 8 or 9 years ago, and I have thought about this question, but I never asked any of my doctors.
doctor
Answered by Dr. Binu Parameswaran Pillai (5 minutes later)
Brief Answer:
Hi

Detailed Answer:
Hi,
Your body will try to attack and destroy thyroid tissues in Hashimoto's disease. This is due to auto immune disease. However. auto immune disease can be self limiting and the destruction of gland depends on the amount of auto immunity body produced. If you have ever done an Anti TPO ( anti thyroid peroxidase), that may give some clue. If the levels are very high, that may indicate a robust auto immune process and likely that the gland is destroyed by auto immunity. This is very common, especially amongst women after child birth

However, not to worry. This is a common disease and easy to treat. Anyways, you are taking Thyroid hormone replacement and that way the gland's deficiency is being taken care of.

Regards
Binu
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Binu Parameswaran Pillai (9 minutes later)
You are just the best doctor, ever, Dr. Binu! I think I already told you, I wish I lived locally to you. I would be a regular patient of yours. One doctor I saw a few years ago. told me I have a mild case of Hashimoto's, but I am confused, because most doctors tell me my thyroid produces, very little thyroid hormone. This doesn't make sense to me. When I see most doctors, they can't explain, how this can be. I'm not sure if you can either, but after this response, I will definitely close the discussion, because for now, I feel like, I have bothered you enough.
doctor
Answered by Dr. Binu Parameswaran Pillai (4 hours later)
Brief Answer:
Hello

Detailed Answer:
Please do not hesitate to ask questions. I enjoy answering them. I might take some time based on my clinic timings and patient load that's all. You are not bothering me at all.

You need to understand little bit about Thyroid auto immune disease ( HAshimoto's disease). Auto immune thyroid disease is due to the immune attack against thyroid by the body. In some people, body's immune system some how consider thyroid cells as a foreign object and mount an attack against it. This is carried out by white blood cells called as lymphocytes and other immune cells.

To put it in simple terms, this is a war against body and thyroid. If the body wins, thyroid tissue will be destroyed.

After the immune attack, initially thyroid will produce small amount of hormones and we will have to supplement the deficient part only. Auto immune attack cmay stop spontaneously and in few lucky people, thyroid will recover partially or fully. But in the vast majority, the immune attack will continue episodically until thyroid is fully destroyed and eventually no hormone will be produced. At this stage, we have to supplement with the full replacement dose.

This process happen over months to years. In women, they are vulnerable for this auto immune attack after pregnancy is over.

I know this is tough to understand. But please do not hesitate to ask further if want clarifications.

Regards
Binu

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Answered by
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Dr. Binu Parameswaran Pillai

Endocrinologist

Practicing since :2003

Answered : 1435 Questions

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Can thyroid function tests be done while fasting?

Brief Answer: Hi Detailed Answer: Hello, Good day and Welcome back Sorry for the delay in reply. I was away in the country side today. Glad to know that the thyroid function tests was normal. The thyroid function tests will be bette if done in the morning before taking the medicine or 4 hours after taking the medicine. But if you are doing only TSH, it can be done anytime. TSH levels tend to be little on higher side by late evening and i advice my patients to get the TSH done before 5 pm. I guess the saliva test your cardilogist want is "midnight salivary cortisol" Regards Binu