Renal Function Tests

Question 0

Waste product of creatine and phosphocreatine

Answer 0

Creatinine

Question 1

Absorbs creatinine

Answer 1

Glomerulus

Question 2

Removes creatinine

Answer 2

Kidneys

Question 3

To which the amount of creatinine that is measured in blood is proportional

Answer 3

Patient’s lean muscle mass

Question 4

Renal physiology

Answer 4

(Review)

Question 5

Best substance to use for glomerular clearance

Answer 5

A chemical that is filtered completely through the glomerulus and not reabsorbed through the nephron tubule

Question 6

Creatinine closely meets the criteria for a substance to be used flor glomerular clearance. Why?

Answer 6

1 Endogenous substance
2 Only around 10% pass through the tubules
3 Creatinine production is constant over time

Question 7

Exogenous substance that must be introduced into the body that can be used for the evaluation of glomerular clearance

Answer 7

Inulin

Question 8

Specimens used for Jaffe reaction

Answer 8

1 Serum
2 Plasma
3 Urine

Question 9

Creatinine reference range: Male (Jaffe)

Answer 9

0.9-1.3 mg/dL

Question 10

Creatinine reference range: Female (Jaffe)

Answer 10

0.6-1.1 mg/dL

Question 11

Creatinine reference range: Children (Jaffe)

Answer 11

0.3-0.7 mg/dL

Question 12

Jaffe reaction

Answer 12

Creatinine reacts with picric acid in an alkaline environment to generate an orange-red product

Question 13

Generate orange-red color in Jaffe reaction

Answer 13

1 Protein
2 Glucose
3 Ascorbic acid
4 Acetone
5 Acetoacetate
6 Cephalosporins

Question 14

Used to produce a measurable product that reflects creatinine concentration

Answer 14

1 Creatininase
2 Creatinase
3 Creatinine deaminase (used more frequently)

Question 15

Factors that may affect creatinine clearance

Answer 15

1 Increased tubular reabsorption of creatinine
2 Reduced creatinine generation from muscle tissue
3 Dietary changes in nitrogenous compounds

Question 16

Formula used for pediatric patients

Answer 16

Schwarz

Question 17

Schwarz formula

Answer 17

Estimates creatinine clearance from serum creatinine

Question 18

Creatinine reference range: Male (Schwarz)

Answer 18

95-130 mL/min

Question 19

Creatinine clearance reference range: Female (Schwarz)

Answer 19

80-120 mL/min

Question 20

Schwarz equation

Answer 20

Creatinine clearance = (k x Ht)Creat

Where 
k=0.45 if 1 year old
k=0.55 if 1-12 years old
Ht=height in cm
Creat=serum creatinine

Question 21

Cockcroft-Gault Equation

Answer 21

Creatinine clearance (mL/min)
= [(140-age) x wt(kg)]/[Serum creatinine (mg/dL) x 72]x0.85 for females

Question 22

Urinary protein methods

Answer 22

1 Turbidometric

2 Dye-binding

Question 23

Turbidometric method for urinary protein

Answer 23

Protein may be precipitated with sulfosalicylic afid, trichloroacetic acid or benzethonium chloride. The turbidity of the precipitate is measured photometrically.

Question 24

Dye-binding method for urinary protein

Answer 24

Dye binds to amino groups and the resulting color change is measured colorimetrically

Question 25

Urinary protein concentration

Answer 25

Urinary protein = [(urine protein concentration, mg/dL) x urine volume, dL]/day

Question 26

Urinary protein test

Answer 26

1 A 12- or 24-hour (preferred, variations) collection may be used 2 Urine should be collected as describe for creatinine clearance 3 Urine should be kept cool

Question 27

Acute glomerular nephritis

Answer 27

1 Sudden onset of hematuria and proteinuria 2 Decrease in glomerular filtration rate 3 Rise in plasma creatinine 4 Fall in creatinine clearance

Question 28

Waste product of the degradation of amino acids into CO2 and ammonia

Answer 28

Urea

Question 29

Azotemia

Answer 29

Excess of urea

Question 30

Physiology of urea

Answer 30

1 Urea is synthesized in the liver 2 It is transported through blood to the kidney, where it is filtered through the glomerulus 3 Almost half of the urea is reabsorbed back into the blood by passive transport in the nephron tubule

Question 31

Factors increasing BUN:Creatinine ratio

Answer 31

1 Prerenal 2 Renal 3 Postrenal

Question 32

Reference range for BUN:Creatinine ratio

Answer 32

10:1 to 20:1

Question 33

Methods for measuring the concentration of urea

Answer 33

1 Urease method | 2 Colorimetric method

Question 34

Specimen for urea

Answer 34

1 Serum 2 Plasma Anticoagulants containing fluoride or citrate should not be used

Question 35

Reference range of urea

Answer 35

Serum or plasma 6-20 mg/dL

Question 36

Reaction principle for urease method

Answer 36

Urea + H2O -- (urease) > 2NH4+ +HCO3-

Question 37

Measurement of ammonia liberated (urease methods)

Answer 37

1 The reaction may be coupled with a reaction that drives NADH to NAD+ 2 The conductivity of the ammonium ion may be measured 3 The Berthelot reaction may be used NH4+ + NaOCl + phenol -- (nitroprusside) > indophenol 4 An indicator dye may be used 5 The reaction may be coupled with another that produces H2O2

Question 38

Principle of colorimetric method for urea

Answer 38

The diacetyl monoxime reaction is used to produce a color change Diacetyl monoxime + urea -- (acid) > diazine (yellow compound)

Question 39

Specimen for urinary microalbumin test

Answer 39

1 A 12- or 24-hour (preferred, variations) collection may be used 2 Urine should be collected as described for creatinine clearance 3 Urine should be kept cool

Question 40

Indicative of microalbuminuria

Answer 40

Excretion of 30 to 300 mg of albumin per 24-hour period on two of three collections

Question 41

Urinary microalbumin test equation

Answer 41

(Urine albumin concentration, mg/dL x urine volume, dL)/day

Question 42

Reaction principle of microalbumin test

Answer 42

Dye binds to albumin and causes a shift in the maximum absorption.

Question 43

Dyes used in urinary microalbumin test

Answer 43

1 Methyl orange 2 Bromcresol green 3 Bromcresol purple

Question 44

Notes on urinary microalbumin test

Answer 44

1 Tests for microalbuminuria must be sensitive to low concentrations of albumin. 2 Urinalysis dipsticks measure protein through the effects of protein on pH; these techniques are not sensitive to low concentrations of albumin in the urine. 3 Semiquantitative immunologic methods screen for low concentrations of albumin. 4 Positive semiquantitative results must be confirmed by a qualitative method.