Can Amitryptyline cause low T4 levels?

[Iveagh]

I have been taking 30 mg Amitryptyline for Neuropathic pain in my neck & arms. A recent blood test showed low levels of T4 . Could this be the Amitryptyline?

[SlowDragon Administrator]

Are you diagnosed as having thyroid disease

Are you currently taking any levothyroxine?

If so how much

Which brand

If on levothyroxine, low Ft4 confirms you need 25mcg dose increase in levothyroxine

For full Thyroid evaluation you need TSH, FT4 and FT3 plus both TPO and TG thyroid antibodies tested. Also EXTREMELY important to test vitamin D, folate, ferritin and B12

Low vitamin levels are extremely common, especially if you have autoimmune thyroid disease (Hashimoto's) diagnosed by raised Thyroid antibodies

Ask GP to test vitamin levels and thyroid antibodies

Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and before eating or drinking anything other than water .

Last dose of Levothyroxine 24 hours prior to blood test. (taking delayed dose immediately after blood draw).

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)

Private tests are available as NHS currently rarely tests Ft3 or thyroid antibodies or all relevant vitamins

List of private testing options

thyroiduk.org/getting-a-dia...

Medichecks Thyroid plus vitamins including folate (private blood draw required)

medichecks.com/products/thy...

Thriva Thyroid plus antibodies and vitamins By DIY fingerpick test

thriva.co/tests/thyroid-test

Thriva also offer just vitamin testing

Blue Horizon Thyroid Premium Gold includes antibodies, cortisol and vitamins by DIY fingerprick test

bluehorizonbloodtests.co.uk...

If you can get GP to test vitamins and antibodies then cheapest option for just TSH, FT4 and FT3

£29 (via NHS private service ) and 10% off if go on thyroid uk for code

thyroiduk.org/getting-a-dia...

monitormyhealth.org.uk/thyr...

[DizzyD]

Hi sorry I have no idea of amitriptyline can cause low T4. Sure more knowledgable people on this site will help you with that. However I do know (from personal experience) that above age 60 amitriptyline can alter Q wave interval levels in the heart. Regardless of your age, check this out of you haven't already done so as some people younger than age 60 have had altered Q wave levels and had to stop taking this drug.

Not trying to alarm you in any way but suggest your GP check your Q wave interval levels. In fact it's advised if you are a certain age Q wave levels should be checked before you take this drug, and checked after taking it to monitor any changes in Q wave activity.

[diogenes Remembering]

This paper describes the interference of drugs like amitryptiline on thyroid function:

Toxicol Appl Pharmacol

. 1998 Apr;149(2):127-35. doi: 10.1006/taap.1998.8367.

Relationship between psychotropic drugs and thyroid function: a review

M F Sauvage 1 , P Marquet, A Rousseau, C Raby, J Buxeraud, G Lachâtre

PMID: 9571980 DOI: 10.1006/taap.1998.8367

Toxicol Appl Pharmacol 1998 Nov;153(1):141

Abstract

Some widely used psychoactive drugs, such as tricyclic antidepressants and antipsychotic phenothiazines exhibit iatrogenic effects on the thyroid. These side effects may arise from interactions at different steps of thyroid hormone biosynthesis. These drugs can induce a change in iodine capture by thyroid cells or can complex iodine, making it unavailable for thyroid hormone synthesis and thus decreasing thyroid hormone blood levels; they can also inhibit thyroid peroxidase activity and thus T3 and T4 synthesis or enhance deiodination of T4 to T3 or to Rt3 by stimulation of deiodinase activity. Moreover, tricyclic antidepressants interfere with the hypothalamic-pituitary-thyroid axis via the noradrenergic or serotonergic systems and might therefore decrease T4 or T3 blood levels, respectively. Phenothiazines can induce autoimmune hypothyroidism, as shown by an increase in the expression of the major histocompatibility complex antigen and by a production of antithyroglobulin or antithyroperoxidase antibodies. However, all these mechanisms are only speculative in humans, as they have only been demonstrated in vitro or in animal experiments. Clinically, thyroid function and affective disorders are closely linked. On one hand, the therapeutic response to antidepressants could be influenced by the thyroid status; on the other hand, the larger the thyroxin decrease induced by antidepressants, the better the therapeutic effect might be. Moreover, cotreatment with thyroid hormones and antidepressant drugs could allow either a decrease in the rate of treatment failure or a faster recovery from depression. As antipsychotic or antidepressant treatments are administered over long periods in humans, their thyroid toxic effects must be taken seriously.