meenasunil
Forum Newbie
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hi , am new to this forum. i needed some help with this physio q. can anyone pls give me the ans to it with explanation.
q- 70kg(154lb) man has a fixed Nacl intake of 200mmol/day. he is given daily inj. of potent mineralocorticoid hormone for 4 days. he is allowed free access to water and consumes usual caloric intake. excretion of Nacl is:
day Nacl (mmol)
1 30
2 90
3 180
4 200
assuming 1L of 0.9% saline contains 150 mmol of Nacl and weighs 1 Kg, how much will this pt. weigh in Kg at end of day 4?
1. 66
2. 68
3. 70
4. 72
5 74
could anyone pls give the ans to above question with an explanation. thanx.
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| tompat
Forum Elite
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me too is new here.
my ans: is 72 kg.
see as per the data, pt. receives 200mmlos/day of sodium.
on day one he lost 30mmol.so the net gain is 170mmols.
similarly he got 110mmols on day 2, 20mmols on day 3 and 0 mmlos on day 4.
tatal gain of sodium is 300mmols. if his guy is maintaining normal body osmolarity i. e. 0.9N then total water he has gained will be 2lit.
( in question stem its given that 0.9N of 1 lit of saline weighs 1 kg).
0.9N=150mmols of Na.
so he has gained 2 kgs.
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| meenasunil
Forum Newbie
Topics: 5
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hi Tompat,
thanx for ur answer. i was really getting disappointed when no one was replying to the q. but think of me as somewhat dumb and pls let me know how u arrived at the qty of water consumed(2 lit).this q was in usmle cbt. thanx.
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| hanwin
Forum Senior
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Posts: 157
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72 kg. Good Q.
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| lq2006
Forum Elite
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72Kg
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| venureddy82
Forum Newbie
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How is 30 mmol lost in first day ? i did not got that pont please explain.
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| tompat
Forum Elite
Topics: 39
Posts: 345
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holy cow,
i dint check back this post, sorry!!
to venu
buddy its given in q stem that he lost 30 mmols on day 1, then 90 mmols on day 2 n so forth.
to meena,
as the q mentions , the guy has free access to water , so what ever water he is going to retain is with which he can maintain normal body osmolarity.
so if he retains 300mmols of NaCL then that means 600 mosmols of NaCL.
which is equal to 2 lit of 0.9 N=Kg
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