Central/2ndary hypothyroid

[Rosa50]

Sorry but can someone explain this please.

[shaws Administrator]

There is some information here which may be helpful and someone who has more knowledge than me will respond too.

Excerpt:

Thyroid UK feels that in many instances, patients should be referred to an endocrinologist to check for central hypothyroidism and other thyroid disorders. However, patients are very rarely referred to an endocrinologist for hypothyroidism as it is considered that the GP can deal with treatment.

There is controversy in regard to when a patient is classed as hypothyroid and whether they should be treated or not.

In America and some other European countries, they have reduced the TSH level to 2.5 which means that anyone above that figure will be treated if they have symptoms of an underactive thyroid.

The 'UK Guidelines for the Use of Thyroid Function Tests' state that, "There is no evidence to support the benefit of routine early treatment with thyroxine in non-pregnant patients with a serum TSH above the reference range but <10mU/L (II,B). Physicians may wish to consider the suitability of a therapeutic trial of thyroxine on an individual patient basis." If your TSH is above the range but less than 10, discuss a therapeutic trial of thyroxine with your doctor.

Subclinical hypothyroidism (where there are elevated TSH levels, but normal FT4 levels, possibly with symptoms) has been found in approximately 4% to 8% of the general population but in approximately 15% to 18% of women over 60 years of age.

[bobsmydog]

I think primary is when there is a problem with the thyroid itself not producing adequate hormones for some reason and secondary is when the pituitary is faulty and so doesn't send the signals to the thyroid to produce the hormones.

So I guess anyone who has had raised TSH could assume they have primary hypothyroidism as the pituitary is doing it's job OK but the thyroid is failing to respond to the signals.

[Clutter]

Rosa50, secondary hypothyroidism presents with low or normal TSH and low FT4. The pituitary gland produces TSH to stimulate the thyroid gland to produce thyroid hormone. Pituitary dysfunction can mean the pituitary gland is unable to produce sufficient TSH stimulation and, although the thyroid gland is usually healthy, the lack of TSH stimulus means the thyroid gland is unable to produce sufficient thyroid hormone. Treatment is Levothyroxine to replace low thyroid hormone.

The pituitary dysfunction should be investigated by an endocrinologist as sex and growth hormones may also be low.

[Bagpuss]

For T 4 to be considered low , would it need to be below the bottom of the range ?

I have had t4 at the bottom of the range - with a 'normal' TSH - Amd even when T4 has sat literally at base of range , Tsh has not risen.

I have never shown antibodies in tesrs so wonder if it's a pituitary issue or thyroid failure ? Not had any explanation except was told 80 % of hypo was autoimmune.

[Hidden]

Hello Rosa50,

I have central / secondary hypothyroidism.

It is usual called Central because it either involves the Pituitary or hypothalamus.

Secondary is pituitary.

Tertiary is hypothalamus.

As it's not always easy to diagnose which gland is causing the problem the term Central is used.

Either way it is treated with Levothyroxine or some form of thyroxine replacement ie T3 or NDT.

If you have an FT4 at the bottom of the range with a TSH which remains low too it is highly likely that you have Central hypothyroidism.

This is what I have and unfortunately due to inept GP's it prevented me from being diagnosed for years. Only my TSH was tested.

In primary hypothyroidism it is the Thyroid gland which ceases to work properly.

In Central hypothyroidism it is either the pituitary gland or the hypothalamus which ceases to signal properly.

THE HYPOTHALAMUS signals THE PITUITARY which Signals THE THYROID!

That is the correct order of things.

In Central hypothyroidism there is basically a breakdown of communication. It is important to have other pituitary hormone levels tested to rule out any other hormone deficiency.

If other pituitary hormones are low this is Hypopituitarism.

This is very rare. So panic not.

Hope this helps

X

[strawberrysorbet in reply to Hidden]

Hi Joesmum, how low was your FT4 when you were medicated? Did you need to see an endo for your diagnosis of central hypo, or did your GP do this?

[Hidden in reply to strawberrysorbet]

I'm so sorry, I replied to this earlier but mustn't have pressed the submit button!

When they finally decided that I had central my bloods looked like this.....

TSH 6.1. (0.4 - 4.6)

FT4. 7. (12-22)

FT3. 2.1. (3.1-6.8)

So as you see the FT's had dropped very low and I was in a very bad way but the TSH remained inappropriately low considering. ( had the TSH been responding correctly, as in primary hypothyroidism, it would have been in the 100's!!)

In Central the TSH doesn't always remain at the very bottom of the range, it can be just below the top of the range or even slightly over as mine was.

[strawberrysorbet in reply to Hidden]

Thanks for your reply! Did you have any other hormones come up as low/high or is it just your thyroid affected?

I've got a TSH of 1.4 and FT4 of 11 (12-22). My cortisol levels came back as "unable to rule out adrenal insufficiency". I'm wondering if I have central but I thought most people with it had a lower TSH than me, so it's interesting for me to see your TSH is higher!

Thanks for coming back to me!

[Hidden in reply to strawberrysorbet]

Yeah you definitely have central with those blood results.

I had a stim test which I passed although my levels more than quadrupled so I may be a bit low on ACTH but certainly managing ok although my thyroxine raises have had to be painfully slow.

My pituitary scan showed an odd shaped pituitary (slightly domed) but no diagnosis of an adenoma. All growth hormones were ok but I had to have my ovaries removed 6 years ago because the pms was intolerable, so maybe my FSH was a bit wonky.

So far my diagnosis is Isolated TSH deficiency. It's rare but not unheard of.

X