Methemoglobin and cyanide poisoning - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
USMLE Articles
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam

Thread Tools Search this Thread Display Modes
Old 04-12-2013
USMLE Forums Scout
Steps History: Not yet
Posts: 40
Threads: 22
Thanked 3 Times in 3 Posts
Reputation: 13
Question Methemoglobin and cyanide poisoning

Can some please explain this concept to me?

According to First Aid, "The oxidized form of hemoglobin (Fe3) doesn't bind O2 as readily but has an increase affinity for CN- (cyanide).

I thought that the oxidized form of hemoglobin (Fe3) has a higher affinity for O2 (oxygen) therefore creating a 'left shift'

And cyanide poisoning on the other hand is when Hemoglobin binds cyanide also creating a left shift.

How are these 2 related???

Someone please explain....
Reply With Quote Quick reply to this message

Old 04-12-2013
MedicalExaminer's Avatar
USMLE Forums Master
Steps History: 1+CK+CS+3
Posts: 824
Threads: 66
Thanked 465 Times in 298 Posts
Reputation: 475

oxidized hemoglobin doesn't bind O2 (so theoretically oxidizing agents right shift the curve)

CN acts on mitochondrial complex 4 (i havent heared of its action causing left shift other than from goljan)

CO on the other hand left shifts the curve
Everything is possible for him who believes (MARK 9:23)
245/247/passed on 1st attempt/223/2mos Obsie /3 US LORS/visa not needed/2008 grad
Reply With Quote Quick reply to this message



Quick Reply

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:
Please enter a password for your user account. Note that passwords are case-sensitive.
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.
Where you live. Leave blank if you don't want to tell.


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
Cyanide and SaO2 stinson USMLE Step 1 Forum 4 03-15-2013 01:16 PM
Lead Poisoning or CO Poisoning? K06100 USMLE Step 2 CK Forum 8 09-30-2012 04:42 PM
Cyanide Poisoning Vitamin! venky2600 USMLE Step 1 Forum 3 08-27-2012 06:23 PM
methemoglobin on the disassociation curve Renaissance USMLE Step 1 Forum 6 08-21-2012 08:23 AM
Oxygen Dissociation Curve for Carbon Monoxide and MetHemoglobin Jackstraw1589 USMLE Step 1 Forum 5 05-26-2011 12:16 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)