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Unformatted text preview: Points Awarded 2.00 Points Missed 3.00 Percentage 40.0% 1. An 80-year-old nursing home resident is brought to you because of poor oral intake. Her serum BUN is 40 mg/dL. sodium 140 meq/L, potassium 3.6 meq/L, chloride 100 meq/L and bicarbonate 24 meq/L. Which of the following is the best parameters to prove her elevated BUN is due to prerenal insult? A) Presence or absence of orthostatic blood pressure and pulse changes B) BUN/creatinine ratio C) Urine osmolality of 400 mOsm/kg H2O D) Fractional excretion of urine sodium < 1 % E) Urine sodium < 20 meq/L Feedback: In addition to anatomical evaluation, study of blood or urine biochemistry may be helpful to distinguish prerenal failure from intrinsic renal diseases. The fractional excretion rate of sodium is most useful for such evaluation. Other parameters are also useful but only with limited value. Orthostatic changes are present in no more than 50 % of patient with hypovolemic prerenal failure ( may be due to activation of renin angiotensin system). Read Page 1758, Harrison's 17th edition.failure ( may be due to activation of renin angiotensin system)....
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This note was uploaded on 10/13/2010 for the course USMLE na taught by Professor Na during the Spring '10 term at St. Matthew's University.
- Spring '10