renal function Flashcards
The degree to which the kidney concentrates the glomerular filtrate can be determined by:
urine to serum osmolality ratio (U/P)
The creatinine clearance (ml/min) is equal to:
[urinary creatinine (mg/L) x volume (ml/min)/plasma creatinine (mg/L)]
Creatinine clearance is used to estimate the:
glomerular filtration rate (GFR)
The principal excretory form of nitrogen is:
urea
Uric acid is the excretory form of nitrogen derived from
purines
Urease hydrolyzes urea to form
ammonia
Uric acid measurement in 24-hour urine samples requires a specific sample collection procedure, part of which is the refrigeration of the sample. This will
prevent bacterial growth which may result in uricase production and breakdown of uric acid in the sample
The normal ratio of urea nitrogen to creatinine in the blood is 10:1 to 20:1. Which of the following indicates prerenal azotemia or uremia?
An increased ratio with normal creatinine
an increased ratio with increased BUN
Which of the following indicates postrenal azotemia (postrenal obstruction)?
increase in BUN to creatinine ratio with increased creatinine level
A common method for the measurement of uric acid is based on the principle of
the reduction of phosphotungstic acid in an alkaline condition to form a blue-colored complex (tungsten blue).
The orange-colored complex developed in the creatinine measurement method called the Jaffe reaction is caused by the complexing of creatinine with:
alkaline picrate
In the Berthelot reaction, the end-product which is measured is:
Indophenol which gives a blue color in proportion to the amount of BUN.
If the generation of ammonium ion s coupled to the enzymatic conversion of NADH to NAD+ in the measurement of BUN, what is actually measured?
A decrease in absorbance as NADH is converted to NAD+
Creatinine, a waste product excreted in the urine, is the anhydride of:
Creatine
Osmolar gap is:
The difference between the calculated and measured osmolality values
A small paper disk is saturated with patient sample (urine or plasma) and heated in a hermetically sealed chamber to a state where the chamber atmosphere is saturated with water. The chamber is then cooled to determine the temperature at which the water vapor condenses. This describes the principle of:
Vapor pressure point depression osmometry
The formulas for calculating serum osmolality of plasma is/are (Select those that apply):
1.86[Na+] + [Glucose]/18 + [BUN]/2.8 + 9
2[Na+] + [Glucose]/20 + [BUN]/3
Which of the following describes the principle of measurement of freezing point osmometry?
The temperature at which the sample freezes is a function of the number of particles in solution.
The solute that contributes the most to the total serum osmolality is:
sodium
