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#1
12-04-2010
 USMLE Forums Guru Steps History: Step 1 Only Posts: 487 Threads: 95 Thanked 1,458 Times in 356 Posts Reputation: 1468
Step 1 practice Qnz - 10

A 45 y/o woman is hospitalized after an automobile accident. The physician collects 1.44L of urine from the patient in a 24hr period. The clinical lab returns the following result.

Plasma creatinine con : 2.0 mg/ml
Plasma urea con : 15 umol/ml
Urine creatinine con : 100 mg/ml
Urine urea con : 160 umol/ml

What is the approx glomerular filtration Rate (GFR) in ml/min of this patient?

A) 10
B) 25
C) 50
D) 75
E) 100

....?

#2
12-04-2010
 USMLE Forums Guru Steps History: 1 + CS Posts: 438 Threads: 111 Thanked 231 Times in 132 Posts Reputation: 241

I think 50. I did it like this:
1.44L/24h is equivalent at 1440ml/24h wich is equivalent at 60ml/h wich is the same as saying 1ml/min. That's the V (urine flow).

Then you do the formula of Clearance of creatinine.

Cl: VxUrine concentration of creatinine
_________________________________
Plasma concentration of creatinie

Cl: 1x100
______
2

 The above post was thanked by: aktorque (12-04-2010), hope12 (05-03-2012)
#3
12-04-2010
 USMLE Forums Guru Steps History: Step 1 Only Posts: 487 Threads: 95 Thanked 1,458 Times in 356 Posts Reputation: 1468

Any one.... !!! come on guy...
#4
12-04-2010
 USMLE Forums Scout Steps History: --- Posts: 95 Threads: 30 Thanked 33 Times in 27 Posts Reputation: 43

 The above post was thanked by: aktorque (12-04-2010)
#5
12-04-2010
 USMLE Forums Guru Steps History: Step 1 Only Posts: 487 Threads: 95 Thanked 1,458 Times in 356 Posts Reputation: 1468

Quote:
 Originally Posted by evavar I think 50. I did it like this: 1.44L/24h is equivalent at 1440ml/24h wich is equivalent at 60ml/h wich is the same as saying 1ml/min. That's the V (urine flow). Then you do the formula of Clearance of creatinine. Cl: VxUrine concentration of creatinine _________________________________ Plasma concentration of creatinie Cl: 1x100 ______ 2 Answer is 50.
Thanks EVAVAR, Your explanation is very impressive. The answer is C) 50 ml/min.
#6
12-04-2010
 USMLE Forums Guru Steps History: 1 + CS Posts: 438 Threads: 111 Thanked 231 Times in 132 Posts Reputation: 241

 The above post was thanked by: aktorque (12-05-2010)

 Tags Physiology-, Renal-, Step-1-Questions

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