Polydipsia, Polyuria, and Hypernatremia! - 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 03-20-2013
USMLE Forums Scout
 
Steps History: ---
Posts: 75
Threads: 12
Thanked 63 Times in 33 Posts
Reputation: 73
Question Polydipsia, Polyuria, and Hypernatremia!

A 22-year-old man comes to the physician's office because of fatigue, blurred vision, and increased thirst for the past 2 months. During this time, he has awakened several times a night to urinate, and urinates 8 to 10 times daily. He takes no medications. Serum sodium concentration is 160 mEq/L and urine osmolality is 165 mOsmol/kg H2O. Which of the following is the most likely diagnosis?

A. Acute renal failure
B. Aldosterone-secreting neoplasm
C. Congestive heart failure
D. Diabetes insipidus
E. Syndrome of inappropriate ADH (vasopressin)

Please explain.
Reply With Quote Quick reply to this message



  #2  
Old 03-20-2013
USMLE Forums Addict
 
Steps History: CS Only
Posts: 127
Threads: 8
Thanked 43 Times in 32 Posts
Reputation: 53
Default .

I think its DI .....

SIADH .... its not SIADH otherwise serum Na would have decreased but here its increased

the rest dont make sense except aldosterone secreting tumor but then they should mention something wrong with serum K as well


Let's see whats the right answer
Reply With Quote Quick reply to this message
The above post was thanked by:
luschka (03-22-2013)
  #3  
Old 03-20-2013
mdsoon's Avatar
USMLE Forums Veteran
 
Steps History: 1+CK+CS
Posts: 259
Threads: 8
Thanked 115 Times in 78 Posts
Reputation: 125
Default

Those are my thoughts exactly.
They should have mention more to hint a tumor, plus he's 22.

DI is a better fit.
Reply With Quote Quick reply to this message
The above post was thanked by:
luschka (03-22-2013)
 
  #4  
Old 03-20-2013
MedicalExaminer's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 824
Threads: 66
Thanked 465 Times in 298 Posts
Reputation: 475
Default

D. Diabetes insipidus more likely fits the clinical scenario


acute renal failure - should be given proper bun/cr

aldosterone secreting tumor will not change urine osmolarity this much (iso osmotic absorption of Na+H2O

CHF-urine is more concentrated due to increased renin + ADH

SIADH-urine is concentrated
__________________
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
The above post was thanked by:
luschka (03-22-2013), nandish_m (03-22-2013), neha_subh (03-23-2013)
  #5  
Old 03-20-2013
USMLE Forums Veteran
 
Steps History: Step 1 Only
Posts: 283
Threads: 35
Thanked 206 Times in 115 Posts
Reputation: 216
Default

Correct answer is D - DI. Think this way. There is one drug that causes DI as well; specifically nephrogenic DI. That will be Litium. Even though this patient never took Litium, DI and Litium's lab value will be identical. That is increase Na+, increase Serum Osm, decrease Urine Osmo and specific < 1.006.
Reply With Quote Quick reply to this message
The above post was thanked by:
luschka (03-22-2013), neha_subh (03-23-2013)
  #6  
Old 03-21-2013
USMLE Forums Addict
 
Steps History: CK Only
Posts: 125
Threads: 24
Thanked 30 Times in 21 Posts
Reputation: 40
Default

why is B a wrong answer if it is indeed wrong
Reply With Quote Quick reply to this message
  #7  
Old 03-21-2013
neha_subh's Avatar
USMLE Forums Veteran
 
Steps History: 1 + CS
Posts: 209
Threads: 18
Thanked 112 Times in 75 Posts
Reputation: 122
Default

this patient is most probably sufered from pituitary tumor---compresion of optic chiasm so visual distrubance---and diabetes insipidius.
decrease ADH---polyuria with decrease urine osmolarity--hypernatremia--ADH injection---increase urine osmolarity..
While with SIADH---increase urine osmolarity.
__________________
lets kick some doors open and help each other to reach our destinies
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
The above post was thanked by:
chilet713 (03-22-2013), drsurge (03-21-2013), luschka (03-22-2013), nandish_m (03-22-2013)
  #8  
Old 03-22-2013
nandish_m's Avatar
USMLE Forums Addict
 
Steps History: Not yet
Posts: 117
Threads: 5
Thanked 59 Times in 40 Posts
Reputation: 69
Default

Quote:
Originally Posted by drsurge View Post
why is B a wrong answer if it is indeed wrong
in aldosterone secreting tumour indeed there is hypernatremia but polyuria is not observed.. as aldosterone causes inc salt n water reabsorption..
while in DI there is inc free water clearance in collectind tubule.

plz correct me if i am wrong.
Reply With Quote Quick reply to this message
The above post was thanked by:
luschka (03-22-2013), neha_subh (03-23-2013)
  #9  
Old 03-22-2013
USMLE Forums Scout
 
Steps History: ---
Posts: 75
Threads: 12
Thanked 63 Times in 33 Posts
Reputation: 73
Correct Answer correct answer D. Diabetes insipidus.

Thanks all for great explanations!

Btw, what is the normal urine osmolality in mOsmol/kg H2O?
Reply With Quote Quick reply to this message
The above post was thanked by:
neha_subh (03-23-2013)



Reply

Tags
Endocrine-, Pathology-, Renal-, 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
hypertension, hypernatremia and hypokalemia earthpole USMLE Step 1 Forum 1 09-14-2011 09:16 PM
Hypertension, Hypernatremia, Hypokalemia, and Hyporeninemia! ricko335 USMLE Step 1 Forum 14 08-02-2011 08:20 AM
primary polydipsia vs diabetes insipidus TAAOM USMLE Step 1 Forum 6 06-04-2011 04:17 AM
Psychotic patient with polydipsia rasheed USMLE Step 1 Classic Clues 1 04-17-2011 09:53 AM
Hypovolumic Hypernatremia FSUSTC USMLE Step 2 CK Forum 2 05-09-2010 10:13 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)