What do thyroid labs look like in a healthy individual?

I was wondering if anyone had your thyroid function tested when it was still optimal, that is, before you even had thyroid disease? What I'm curious to know is what labs (TSH, fT4, fT3) more or less look like in an individual with a healthy thyroid gland and no symptoms of even subclinical hypoT.

I imagine that, as the human thyroid gland secretes mainly T4, and only a little T3, fT3 levels in a healthy individual will be lower than fT4 levels?

I realise it varies from person to person, but I'd be curious to find out if anyone remembers what your labs looked like when you were healthy and feeling fine. When I had my thyroid function tested for the first time I already had overt hypothyroidism (Hashimoto's).

[SeasideSusie Remembering]

I'd be surprised if anyone had their thyroid function tests done as a matter of routine. It ought to be done really, that would give us a baseline to know where we are well, and an indication of what possibly to aim for if we develop thyroid disease and have treatment.

[GarryB in reply to SeasideSusie]

Since my thyroid decided to die I have thought so many times I wish I knew my hormone levels when I was healthy. At least one blood test should be done on every person to establish a base reference to go from should thyroid issues develop in the future. I'd like my daughters to have this done when they are adults.

[SeasideSusie Remembering in reply to GarryB]

I've suggested to my daughter that because I've been hypo since my mid-20s, and my mother had hypothyroidism too, then she may very well develop it at some stage and it would be a good idea to get a baseline while she's OK. It's fallen on deaf ears, and she's a very sensible 49 year old!

I'm not even going to suggest it to my son, because, of course, he's invincible like so many men (no offence meant Garry )

[GarryB in reply to SeasideSusie]

I've thought about how strong I was before this. No man can beat hypothyroidism; we know that. It crushes all alike.

[MaisieGray]

The majority of healthy euthyroid people will have levels that fit somewhere within the reference interval for the respective hormones - that, in theory at least, is how the reference intervals are arrived at. The testing that provided those lower and higher levels returned a statistical bell curve, and of course some perfectly healthy people will also be outliers to that bell curve. So there is no single set of levels that every healthy euthyroid person will have. For myself, I don't believe there is a relevance either, to what our levels were, pre-thyroid dysfunction, to what they might be once we become people with thyroid dysfunction or people with no thyroid. Or more accurately, for me, I don't see the value of chasing what once was but is no more. In any case, the general process of aging might be impacting contemporary hormone levels - if I hadn't become hypothyroid 40 years who is to say that my levels now would be anything like they were then, even if I was well during both periods. The aim is to feel well with the best intermittent daily doses of exogenous hormones, and what we were before, with natural access to endogenous hormones, I believe, can't be compared.

[Hidden in reply to MaisieGray]

Makes a lot of sense to me...too bad most doctors won't agree...!

[diogenes Remembering]

In health you will be somewhere in the approx range 10-23 mol/L for FT4 and about 3.5-7.2 for FT3. Wherever it is, that is your stable level. It does not in life cover the whole of the range but stays within a narrow corridor individual for you. I know that I am Mr average, right in the middle for both parameters, as 2/3 of people are. But that does not mean you are in that area. It is truly sad that we do not get a FT4 and FT3 test in health, to archive against the time if illness strikes. Then you have a target to aim at instead of flailing about.

[Hidden in reply to diogenes]

Interesting...meaning a person can feel well when falling anywhere between those very broad ranges...?!

[diogenes Remembering in reply to Hidden]

No the opposite. We each occupy a unique narow band within each range that defines our optimum health. Outside that we are not optimally well.

[Angel_of_the_North]

I doubt anyone knows as you don't tend to get a full thyroid panel done if you are healthy. However, studies suggest that the highest number of healthy people have a TSH of about 1.2. All the ranges are just done from people who haven't been diagnosed, not people who are bouncing with health - and we know what that means

[Hidden in reply to Angel_of_the_North]

Interesting,...I just read an article by US natural doctor Westin Childs who works with NDT/T3 and says that, in all of his years in practice, he has never seen a truly healthy individual with a TSH above 1...which is pretty close to what you suggest, and no way near the reference ranges most labs use.