Amiodarone Hypo or Hyper thyroidism? - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 2 CK Forum

USMLE Step 2 CK Forum USMLE Step 2 CK Discussion Forum: Let's talk about anything related to USMLE Step 2 CK exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-07-2010
USMLE Forums Scout
 
Steps History: Step 1 Only
Posts: 17
Threads: 1
Thanked 3 Times in 3 Posts
Reputation: 13
Drug Amiodarone Hypo or Hyper thyroidism?

I've seen conflicting references about Amiodarone and it's effect on thyroid status.
What does it cause hypothyroidism or hyperthyroidism?
Reply With Quote Quick reply to this message
The above post was thanked by:
drgabroomunda (09-07-2011)



  #2  
Old 02-07-2010
USMLE Forums Veteran
 
Steps History: 1+CK+CS+3
Posts: 247
Threads: 61
Thanked 275 Times in 105 Posts
Reputation: 305
Default

Amiodarone can cause both ... It can cause hypothyroidism by inhibiting deaminase causes decrease active T3 formation .... It can cause hyperthyroidism as amiodarone has iodine in it , and this excess iodine can cause more Thyroid hormone production . So it can do Hypo or Hyper thyroidism ...
Reply With Quote Quick reply to this message
The above post was thanked by:
anoop_1198 (05-18-2010), drgabroomunda (09-07-2011), Felis chaus (06-15-2015), Idaho1 (02-08-2010), shaheer (08-12-2010), tarsuc (04-05-2013)
  #3  
Old 02-07-2010
Karrar's Avatar
USMLE Forums Scout
 
Steps History: Not yet
Posts: 14
Threads: 3
Thanked 28 Times in 6 Posts
Reputation: 68
Default

In the begining it's effect is stimulatory ---- Hyperthyroidism
but later on it will inhibit the thyroid ------- Hypothyroidism
(Just like Iodine suppliment)
__________________
Karrar Khaleel
Reply With Quote Quick reply to this message
The above post was thanked by:
anoop_1198 (05-18-2010), drgabroomunda (09-07-2011), shaheer (08-12-2010), tarsuc (04-05-2013)
 
  #4  
Old 02-07-2010
USMLE Forums Scout
 
Steps History: Step 1 Only
Posts: 17
Threads: 1
Thanked 3 Times in 3 Posts
Reputation: 13
Default

Quote:
Originally Posted by Karrar View Post
In the begining it's effect is stimulatory ---- Hyperthyroidism
but later on it will inhibit the thyroid ------- Hypothyroidism
(Just like Iodine suppliment)
Can you explain the mechanism, I don't understand how Iodine cause hyper then hypo
Reply With Quote Quick reply to this message
  #5  
Old 02-08-2010
Karrar's Avatar
USMLE Forums Scout
 
Steps History: Not yet
Posts: 14
Threads: 3
Thanked 28 Times in 6 Posts
Reputation: 68
Post Iodine complex effect on Thyroid gland

When thre is excess Iodine in the circulation it will be entrapped by thyroid follicles and subsequently organized and coupled to be released as T4 & T3 in excess amounts.
With time, build up of greater amounts of Iodine within the gland will lead to inhibition of many steps involved in T. hormone synthesis (transport, coupling and even release of hormones).

This happens in a way somewhat similar to the down-regulation process in receptors; when u give an acetylcholine agonist, e.g. Physostigmine (Cholinestrase inhibitor), in therapeutic dose there will be improvement of muscle contraction while in overdose it will cause flaccid paralysis by accummulation of Ach in synaptic cleft.

Hyper- & Hypothyroidism ----------both r caused by Iodine
Contraction & Paralysis -----------both r caused by Ach

Keep in mind that Radiocontrast media contains Iodine and can affect the thyroid by the same mechanism.

I don't know if there is direct effect of Iodine on the TSH or TRH release, anyone knows about that??
__________________
Karrar Khaleel

Last edited by Karrar; 02-12-2010 at 12:15 PM.
Reply With Quote Quick reply to this message
The above post was thanked by:
anoop_1198 (05-18-2010), drgabroomunda (09-07-2011), Felis chaus (06-15-2015), Idaho1 (02-08-2010), lee-usmle (02-08-2010), Pachys (08-01-2013), Sabio (02-08-2010)
  #6  
Old 02-08-2010
YoramFishke's Avatar
USMLE Forums Veteran
 
Steps History: 1+CK+CS
Posts: 248
Threads: 11
Thanked 311 Times in 127 Posts
Reputation: 341
Default Amiodarone effects on TSH

Quote:
Originally Posted by Karrar View Post
I don't know if there is direct effect of Iodine on the TSH or TRH release, anyone knows about that??
Yes, Amiodarone has effects on TSH and TRH.
  • Amiodarone inhibits type 1 5'-deiodinase enzyme activity, thereby decreasing the peripheral conversion of T4 to triiodothyronine (T3) and reducing the clearance of both T4 and reverse T3 (rT3). Consequently, the serum levels of T4 and rT3 increase and the serum levels of T3 decrease by 20-25%.
  • Amiodarone inhibits entry of T4 and T3 into the peripheral tissue. Serum T4 levels increase by an average of 40% above pretreatment levels after 1-4 months of treatment with amiodarone. This, in itself, does not constitute evidence of hyperthyroidism (thyrotoxicosis).
  • Amiodarone causes inhibition of type 2 5'-deiodinase enzyme activity in the pituitary due to feedback regulation is seen in the first 1-3 months of therapy and leads to an increase in thyroid-stimulating hormone (TSH) levels. This is not an indication for T4 replacement in these patients. Serum TSH levels return to normal in 2-3 months as T4 concentrations rise sufficiently to overcome the partial block in T3 production. The response of TSH to thyroid-releasing hormone (TRH) may be reduced.
Reference: http://emedicine.medscape.com/article/129033-overview
Reply With Quote Quick reply to this message
The above post was thanked by:
aisakya (12-17-2011), anoop_1198 (05-18-2010), drgabroomunda (09-07-2011), Felis chaus (06-15-2015), Idaho1 (02-08-2010), Karrar (02-08-2010), lee-usmle (02-08-2010), studyhard (07-27-2010)
  #7  
Old 02-12-2010
ManuHarish
Guest
 
Posts: n/a
Threads: 51
Default

I also would like to add that there are other 5' deiodinase enzyme inhibitors.
These are
Propyl thiouracil (at high doses) and Lithium
Reply With Quote Quick reply to this message
The above post was thanked by:
aisakya (12-17-2011), anoop_1198 (05-18-2010)
  #8  
Old 02-12-2010
USMLE Forums Scout
 
Steps History: 1+CK+CS
Posts: 55
Threads: 7
Thanked 108 Times in 24 Posts
Reputation: 118
Default

Quote:
Originally Posted by ManuHarish View Post
I also would like to add that there are other 5' deiodinase enzyme inhibitors.
These are
Propyl thiouracil (at high doses) and Lithium
And also steroids
Reply With Quote Quick reply to this message
The above post was thanked by:
aisakya (12-17-2011), anoop_1198 (05-18-2010)
  #9  
Old 02-13-2010
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 742
Threads: 137
Thanked 2,461 Times in 441 Posts
Reputation: 2564
Default

Also have a look here
http://www.usmle-forums.com/usmle-st....html#post5242
Reply With Quote Quick reply to this message
The above post was thanked by:
anoop_1198 (05-18-2010)
  #10  
Old 05-14-2011
USMLE Forums Newbie
 
Steps History: Not yet
Posts: 1
Threads: 0
Thanked 0 Times in 0 Posts
Reputation: 10
Question recovery time from side effect

After discontinuation of amiodarone does anyone know the recovery time for the side effect hyper-hypo thyroid?
Reply With Quote Quick reply to this message



Reply

Tags
Endocrinology-, Internal-Medicine-, Pharmacology-

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Aspirin or Amiodarone to prevent recurrent AFs! anoop_1198 USMLE Step 2 CK Forum 3 05-18-2010 07:25 AM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)