-----Original Message-----
From: Frost, Stephen [mailto:[log in to unmask]]
Sent: 06 November 2002 11:43
To: [log in to unmask]
Subject: Re: Amiodarone and TFTsI assume this helpful summary relates to the latest report of the UKNEQAS on interpretative comments.
For information, another useful short review of amiodarone induced thyroid dysfunction is given in "Controversial aspects of thyroid disease", Hanna FWF, Lazarus JH and Scanlon MF, BMJ 319, 2 October 1999, p894-899. From the comments of the variability of assessors comments, I assume they have not all read this or similar reviews before marking. Or is the literature divergent?
regards
Stephen Frost
----Original Message-----
From: Mohammad Al-Jubouri [mailto:[log in to unmask]]
Sent: Tuesday, November 05, 2002 2:56 PM
To:
Subject: Amiodarone and TFTs
Dear All
The majority of patients given amiodarone remain
euthyroid however in 14-18% of cases, overt thyroid
changes develop.There are two types of thyroid dysfunction induced by
amiodarone;1. Amiodarone induced hypothyroidism (AIH), occurs in
iodine sufficient areas. This is more frequent than
AIT and if amiodarone is necessary for treating the
underlying cardiac disorder then it can be continued
in association with thyroxine replacement therapy.2. Amiodarone induced thyrotoxicosis (AIT), occurs in
iodine deficient areas. There are two types of AIT,
type I occurs in abnormal glands and is due to iodine
induced excessive thyroid hormone synthesis. Type II
is a form of destructive thyroiditis and it usually
occurs in those with pre-existing normal thyroid
glands. Treatment of AIT type I is by antithyroid
drugs (carbimazole, methimazole), higher doses are
usually necessary because of resistance to treatment.
Addition of potassium perchlorate to deplete
intrathyroidal iodine is also advisable. In AIT type
II antithyroid drugs are not effective and steroid
should be given in high doses over several weeks.
Discontinuation of amiodarone is advised if feasible.
In both types if medical therapy fails, total
thyroidectomy should be considered.It is essential to evaluate patients before and after
amiodarone therapy. A careful thyroid gland
examination and perhaps thyroid ultrasound to detect
nodular or diffuse goitre since there is increased
risk of developing AIT which can occur years after
starting amiodarone treatment. Baseline serum TSH, FT4
and FT3 are recommendedso that changes in these hormones during treatment can
be monitored. Patients positive for thyroid peroxidase
antibodies are more liable for AIH which most often
occurs during the first year of therapy. Repeat tests
and clinical examination of thyroid every 6 months is
recommended. If patients develop symptoms the
evaluation period can be shortened. A rise in TSH
indicates the development of AIH while a decrease in
TSH and rise in FT3 and FT4 suggests the development
of AIT.I hope this is helpful.
Best wishes.
Mohammad
=====
Dr. M A Al-Jubouri
Consultant Chemical Pathologist__________________________________________________
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