A 72-year-old man is brought to the emergency department due to diarrhea and vomiting for the last 24 hours. The patient's daughter states that he has been unable to take in much fluid during this time. He has hypertension treated with hydrochlorothiazide, which he has not taken since the onset of symptoms. Blood pressure is 90/60 mm Hg and pulse is 105/min. Examination shows dry mucous membranes. Urinalysis reveals concentrated urine with a specific gravity of 1.030. Which of the following changes in renal plasma flow (RPF), glomerular filtration rate (GFR), and filtration fraction (FF) are most likely to be present in this patient as compared with the normal state?

Question

A 72-year-old man is brought to the emergency department due to diarrhea and vomiting for the last 24 hours.  The patient's daughter states that he has been unable to take in much fluid during this time.  He has hypertension treated with hydrochlorothiazide, which he has not taken since the onset of symptoms.  Blood pressure is 90/60 mm Hg and pulse is 105/min.  Examination shows dry mucous membranes.  Urinalysis reveals concentrated urine with a specific gravity of 1.030.  Which of the following changes in renal plasma flow (RPF), glomerular filtration rate (GFR), and filtration fraction (FF) are most likely to be present in this patient as compared with the normal state?

Quizplus · Accepted Answer

Eductional Objective: Hypovolemia results in a reduced renal plasma flow (RPF) and glomerular filtration rate (GFR).  This leads to compensatory efferent arteriolar vasoconstriction, which raises the filtration fraction and maintains GFR at near-normal levels.  As RPF continues to decline, increasing glomerular oncotic pressure will eventually overwhelm the compensatory increase in hydrostatic pressure, leading to a precipitous drop in GFR and renal failure.

A 72-Year-Old Man Is Brought to the Emergency Department Due