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#1
07-12-2011
 USMLE Forums Guru Steps History: --- Posts: 332 Threads: 48 Thanked 170 Times in 109 Posts
question on electrolye metabolism

A 50 year old man weighs 70 kg, on a fixed NaCl intake 200mmol/day, is given injection of powerful mineral corticosteroid daily for 4 days. He has free access to water during these 4 days. Daily NaCl excretion is bellow:

day 1, 30 mmol
day 2, 90 mmol
day 3, 180 mmol
day 4, 200 mmol
assuming 150 mmol is 1 Kg in weight, what is his weight by the end of day 4
1, 60 kg
2, 74 kg
3, 75 kg
4, 72 kg
 The above post was thanked by: jahn77 (07-13-2011), pnreddy (07-13-2011)

#2
07-12-2011
 USMLE Forums Master Steps History: 1 + CK Posts: 623 Threads: 62 Thanked 289 Times in 186 Posts Reputation: 299

Quote:
 Originally Posted by usluipek A 50 year old man weighs 70 kg, on a fixed NaCl intake 200mmol/day, is given injection of powerful mineral corticosteroid daily for 4 days. He has free access to water during these 4 days. Daily NaCl excretion is bellow: day 1, 30 mmol day 2, 90 mmol day 3, 180 mmol day 4, 200 mmol assuming 150 mmol is 1 Kg in weight, what is his weight by the end of day 4 1, 60 kg 2, 74 kg 3, 75 kg 4, 72 kg

the ans is 72 kg the key is to see hw mch has been absorbed in body by subtracting from the amount xcreted by day 4 no absorption has occured n in the last three days person has absorbed 300mmol NaCl n this is equal to 2 kg hence the wt is 72
 The above post was thanked by: Hope2Pass (07-13-2011), jahn77 (07-13-2011), Meli (07-13-2011), usluipek (07-13-2011)
#3
07-13-2011
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good question..,is it 4.)72kg
 The above post was thanked by: usluipek (07-13-2011)

#4
07-13-2011
 USMLE Forums Guru Steps History: --- Posts: 332 Threads: 48 Thanked 170 Times in 109 Posts

Can someone explain how "injection of mineralcortisone" impact the Na metabolism, how are we supposed to use this information in this question?
#5
07-13-2011
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Quote:
 Originally Posted by usluipek Can someone explain how "injection of mineralcortisone" impact the Na metabolism, how are we supposed to use this information in this question?
A mineral corticosteroid would mean mineralocorticoid ... which is Aldosterone!
 The above post was thanked by: usluipek (07-13-2011)
#6
07-13-2011
 USMLE Forums Guru Steps History: --- Posts: 332 Threads: 48 Thanked 170 Times in 109 Posts

Hope2 pass, We all know mineralcorticoid is aldosterone. what I was asking is how we use this information, does the aldosterone injection affects the answer or it is just a smoking gun?
#7
07-13-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,684 Threads: 213 Thanked 1,600 Times in 660 Posts Reputation: 1610

Quote:
 Originally Posted by usluipek Hope2 pass, We all know mineralcorticoid is aldosterone. what I was asking is how we use this information, does the aldosterone injection affects the answer or it is just a smoking gun?
Oh ok, Well its just a distractor coz you dont need to use that information to answer the question! All we need is the amount of intake & excretion of Na.

Intake Excreted Reabsorbed
Day 1 - 200 30 170
Day 2 - 200 90 110
Day 3 - 200 180 20
Day 4 - 200 200 0

Total reabsorbed in 4 days = 300 mmol
Since 150 mmol = 1 Kg, the pt gained a total of 2 Kg, therefore Ans = 72 Kg.
 The above post was thanked by: usluipek (07-13-2011)

 Tags Biochemistry-, Physiology-, Renal-

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