Hemolytic anemia & sulfas - 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 1 Forum

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


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 05-19-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,261 Times in 881 Posts
Reputation: 3271
Blood Hemolytic anemia & sulfas

A 5-year-old Egyptian boy receives a sulfonamide antibiotic as prophylaxis for recurrent urinary tract infections. Although he was previously healthy and well-nourished, he becomes progressively ill and presents to your office with pallor and irritability. A blood count shows that he is severely anemic with jaundice due to hemolysis of red blood cells. Which of the following would be the simplest test for diagnosis?

a. Northern blotting of red blood cell mRNA
b. Enzyme assay of red blood cell hemolysate
c. Western blotting of red blood cell hemolysates
d. Amplification of red blood cell DNA and hybridization with allele-specific oligonucleotides (PCR-ASOs)
e. Southern blot analysis for gene deletions
Reply With Quote Quick reply to this message
The above post was thanked by:
dr-ahmed (05-19-2011), dr.muhamad (05-20-2011), Fazle rabbi (05-20-2011), Lena (05-21-2011), Taiwan_Guy (05-21-2011)



  #2  
Old 05-19-2011
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,175
Threads: 38
Thanked 852 Times in 478 Posts
Reputation: 862
Default

Quote:
Originally Posted by bebix View Post
A 5-year-old Egyptian boy receives a sulfonamide antibiotic as prophylaxis for recurrent urinary tract infections. Although he was previously healthy and well-nourished, he becomes progressively ill and presents to your office with pallor and irritability. A blood count shows that he is severely anemic with jaundice due to hemolysis of red blood cells. Which of the following would be the simplest test for diagnosis?

a. Northern blotting of red blood cell mRNA
b. Enzyme assay of red blood cell hemolysate
c. Western blotting of red blood cell hemolysates
d. Amplification of red blood cell DNA and hybridization with allele-specific oligonucleotides (PCR-ASOs)
e. Southern blot analysis for gene deletions
Answer is B) Enzyme assay of red blood cell hemolysate
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (05-19-2011)
  #3  
Old 05-19-2011
USMLE Forums Guru
 
Steps History: Not yet
Posts: 298
Threads: 45
Thanked 718 Times in 210 Posts
Reputation: 728
Default

The "easiest" part of this question stem is making this a bit difficult because I'm by no means a lab expert.

I'm between A and B because I think both can detect a G6PD deficiency. As for which one is easier, I'll go with the more commonly used test which is a northern blot. Enzyme assay seems like it might be complicated but then again, I'm not really sure how they are done.

So I'd guess A
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (05-19-2011)
 
  #4  
Old 05-19-2011
USMLE Forums Scout
 
Steps History: 1+CK+CS+3
Posts: 55
Threads: 6
Thanked 15 Times in 15 Posts
Reputation: 25
Default

answer is B


B) Enzyme assay of red blood cell hemolysate

???

Last edited by prataptetali; 05-19-2011 at 09:44 PM. Reason: spelling mistake
Reply With Quote Quick reply to this message
  #5  
Old 05-19-2011
USMLE Forums Guru
 
Steps History: Not yet
Posts: 298
Threads: 45
Thanked 718 Times in 210 Posts
Reputation: 728
Default

Quote:
Originally Posted by apx85 View Post
The "easiest" part of this question stem is making this a bit difficult because I'm by no means a lab expert.

I'm between A and B because I think both can detect a G6PD deficiency. As for which one is easier, I'll go with the more commonly used test which is a northern blot. Enzyme assay seems like it might be complicated but then again, I'm not really sure how they are done.

So I'd guess A
So after taking a second look at this question, i realized that RBC's dont have any DNA left so there is no mRNA to detect! Only answer choices B and C make sense knowing that RBC's no longer have nucleus/DNA

I'd go with B
Reply With Quote Quick reply to this message
  #6  
Old 05-19-2011
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,175
Threads: 38
Thanked 852 Times in 478 Posts
Reputation: 862
Default

Quote:
Originally Posted by apx85 View Post
So after taking a second look at this question, i realized that RBC's dont have any DNA left so there is no mRNA to detect! Only answer choices B and C make sense knowing that RBC's no longer have nucleus/DNA

I'd go with B
Yea, that's what i thought after I looked at your answer...

"how is this guy going to assay mRNA if RBC's are not nucleated?" lol
Reply With Quote Quick reply to this message
  #7  
Old 05-20-2011
USMLE Forums Newbie
 
Steps History: Not yet
Posts: 1
Threads: 0
Thanked 1 Time in 1 Post
Reputation: 11
Default

The boy has been suffered from G6PD deficiency,so sulfonamide causes drug induced haemolytic anaemia....

So,enzyme assay is the choice
Reply With Quote Quick reply to this message
The above post was thanked by:
Proxery (05-20-2011)
  #8  
Old 05-20-2011
dr.muhamad's Avatar
USMLE Forums Guru
 
Steps History: 1 + CS
Posts: 300
Threads: 22
Thanked 97 Times in 62 Posts
Reputation: 107
Default

bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
Reply With Quote Quick reply to this message
  #9  
Old 05-20-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,261 Times in 881 Posts
Reputation: 3271
Default correct answer

The answer is b.

Red cell hemolysis after drug exposure suggests a red cell enzyme defect, most easily confirmed by enzyme assay to demonstrate deficient activity. A likely diagnosis here is glucose-6-phosphate dehydrogenase (G6PD) deficiency.
DNA analysis is available to demonstrate particular alleles, but simple enzyme assay is sufficient for diagnosis.
Reply With Quote Quick reply to this message
The above post was thanked by:
dr.muhamad (05-20-2011), Fazle rabbi (05-20-2011), Taiwan_Guy (05-21-2011)
  #10  
Old 05-20-2011
dr.muhamad's Avatar
USMLE Forums Guru
 
Steps History: 1 + CS
Posts: 300
Threads: 22
Thanked 97 Times in 62 Posts
Reputation: 107
Default

Quote:
Originally Posted by bebix View Post
The answer is b.

Red cell hemolysis after drug exposure suggests a red cell enzyme defect, most easily confirmed by enzyme assay to demonstrate deficient activity. A likely diagnosis here is glucose-6-phosphate dehydrogenase (G6PD) deficiency.
DNA analysis is available to demonstrate particular alleles, but simple enzyme assay is sufficient for diagnosis.
just to make sure :the DNA analysis needs a bone marrow sample???
coz its gonna be from blastocytes right??
Reply With Quote Quick reply to this message
  #11  
Old 05-20-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,261 Times in 881 Posts
Reputation: 3271
Default

Quote:
Originally Posted by dr.muhamad View Post
just to make sure :the DNA analysis needs a bone marrow sample???
coz its gonna be from blastocytes right??
you could use any cell "with" nucleus (saliva or blood)

ref:
Maffi D., Pasquino M.T., Caprari P., Caforio M.P., Cianciulli P., Sorrentino F., Cappabianca M.P., Salvati A.M.
Identification of G6PD Mediterranean mutation by amplification refractory mutation system
(2002) Clinica Chimica Acta, 321 (1-2), pp. 43-47.
Reply With Quote Quick reply to this message
The above post was thanked by:
dr.muhamad (05-20-2011), prataptetali (05-20-2011)
  #12  
Old 05-21-2011
USMLE Forums Veteran
 
Steps History: 1+CK+CS
Posts: 274
Threads: 9
Thanked 336 Times in 126 Posts
Reputation: 346
Default

Nice one,
For this I looked at answer options b4 looking at question.
Looking at question, immediately see G6PD and know that cause of that is enzyme related so know dx is based on B
Reply With Quote Quick reply to this message
  #13  
Old 05-21-2011
USMLE Forums Scout
 
Steps History: 1 + CK
Posts: 91
Threads: 17
Thanked 108 Times in 37 Posts
Reputation: 118
Default

Quote:
Originally Posted by Lena View Post
Nice one,
For this I looked at answer options b4 looking at question.
Looking at question, immediately see G6PD and know that cause of that is enzyme related so know dx is based on B
it's easy though Egytian or north africain it's a buzz word; I said G6PD even before reading the question
Reply With Quote Quick reply to this message



Reply

Tags
Genetics-, Hematology-, Step-1-Questions

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
Anemia of Chronic Disease : Micro or Normocytic anemia? lemontea88 USMLE Step 1 Forum 8 09-27-2011 04:20 PM
Beta Hemolytic Microorganisms lee-usmle USMLE Step 1 Buzzwords 1 09-18-2011 11:18 AM
Immunological Mechanism of Hemolytic Transfusion Reaction! Dr_Laura USMLE Step 1 Forum 8 05-10-2011 11:50 AM
Which enzyme deficiency causing this hemolytic anemia? sam01 USMLE Step 1 Forum 8 04-14-2010 04:17 AM
Hemolytic Uremic Syndrome and Antibiotics! FSUSTC USMLE Step 2 CK Forum 1 03-01-2010 10:03 PM

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)