Math-in-CTE Lesson Plan Template
Lesson Title: What’s a 24-hour urine and what’s the deal with
creatinine clearance
Author(s):
Phone Number(s):
Valerie Leek
856-451-9000 x259
Ted Archer
856-451-9000 x261
Lesson # 19
E-mail Address(es):
vleek@cumberland.tec.nj.us
tarcher@cumberland.tec.nj.us
Occupational Area: Allied Health
CTE Concept(s): Collection of a 24-hour urine for creatinine clearance to diagnose renal disease. Correlate glomerular filtration
with elimation of nitrogenous wastes (learned previously; review). Correct collection method including collection from voids and
foley catheter. Importance of collecting all urine produced by the kidneys in a 24 hour period. Correct storage of urine (on ice)
during the collection time. What is creatinine, a nitrogenous waste. What elevated levels mean when found in the blood. Normal
creatinine clearance rate. Correctly reading (at eye level) and recording urine output during collection. Placing signage in the client
room to promote continuation of care. Compare serum levels of creatinine to that cleared in urine.
Math Concepts: Standard solid (pounds to kilograms; grams per liter to milligrams per deciliter ) and liquid metric conversions,
(ounces to milliliters), percentages, interpreting a nomogram and utilizing technology to calculate body surface area in m2.
Calculating formulas which include multiplication and division. Determining rate by forming a ratio for the clearance assessment
Expressed in mL/min.
Lesson Objective:
Supplies Needed:
Collection of a 24-hour urine for creatinine clearance. Identification of the calculation behind the theory of
collecting all urine voided. Introduction to the concept of body surface area that will be covered in other areas of st
of study like burns and body mass index.
Foley catheter, bedpan, graduate, basin, ice, tinted urine holder, signage, intake and output sheet, nomograms and
links to online nomograms and online calculation of body surface area (BSA), calculator, formula, gloves,
simulated urine, PowerPoint describing 24-hour urine collection and creatinine clearance
to determine ability of kidneys to eliminate nitrogenous wastes. Simulator dummies, beds, linens and bedside
furniture.
THE "7 ELEMENTS"
TEACHER NOTES
(and answer key)
1. Introduce the CTE lesson.
As nursing assistants, we may need to collect many different Introduction of skill
types of urine samples. One of the most complicated for many to
learn and understand is the 24-hour urine. We will go to the
nursing lab and practice collecting urine.
Did you know that we can tell how the kidneys are working by The blood is a serum study that will show all products of metabolism
in the sample. We would expect that wastes that are supposed to be
comparing what is in the blood with what is in the urine?
eliminated in the urine will be in the urine.
A normal glomerular filtration rate is 125 mL/min (the kidneys filter
Do you recall the normal glomerular filtration rate and what that
180 L/day, but due to hormonal influences the urine amount is only
would mean for clearance of any waste from the blood (azotemia)
approximately 1.5 L-2 L/day.
Do you know what a nitrogenous waste is and where it comes
from?
Nitrogenous wastes include creatinine, uric acid, ammonia and urea
and come from protein (the only nutrient that contains nitrogen).
Did you know that one of the tests, the creatinine clearance test, Most of the nitrogenous wastes are eliminated by healthy kidneys.
depends on the exact and complete collection of urine by the
nurse. If one drop is lost, the test must be started over again and
The creatinine clearance test is a calculation that compares the
the client may have to stay in the hospital another day.
serum creatinine level with that found in the urine. It can also be a
“corrected” creatinine level when the body surface area (BSA) is
We will collect urine, measure it accurately, and store it in ice to taken into consideration
preserve the components. I will show you the exact steps to take
Once the skill is mastered, we will calculate a simulated creatinine
Urine must be kept on ice to preserve solutes
clearance rate using a multiplication/division/body surface area
formula. We will determine if the client is clearing nitrogenous
wastes properly from his body.
A body surface area determination can be made from using a
nomogram or by going to a BSA calculation site will allow a
corrected creatinine clearance rate by utilizing the formula that
includes the BSA
2. Assess students’ math awareness as it relates to the CTE
lesson.
Have you ever measured urine?
What supplies would you need to measure urine? A cup, a box, a
A graduate container that measures in milliters (mL)
scale….what would you use?
The urine would remain in the foley bag, placed in an ice bath and
What collection method would we use if the client has a catheter?
emptied at the end of the shift, using a graduate container (mL)
Can you convert pounds to kilograms?
Can you convert inches to centimeters?
1 kg=2.2 lbs. Multiply kg by 2.2 to get lbs.
Take the number of inches and multiply it by 2.54. So for
example, 8 inches would be 20.3 cm (8 x 2.54 = 20.3).
Can you read a graph for intersecting lines?
Show the nomogram on screen, and demonstrate how kilogram
weight and height in centimeters intersect.
Can you use a formula to calculate and compare normal and abnormal
Show the formula: Calculation is mL of plasma cleared by glomerular
values?
filtration per minute per standard surface area
UV X 1.73
P
A
Where:
U= concentration of creatinine in urine in mg/dl. Before calculation,
multiply total creatinine excreted (reported as g/L). Multiply g/L by
100 to obtain mg/dl
P=concentration of creatinine in plasma in mg/dl
V=volume of urine in mL divided by the time of collection in minutes
A=body surface area in square meters. Calculate body surface area
of patient from standard nomogram or nomogram calculation
website.
3. Work through the math example embedded in the CTE lesson.
WHO recommended that only urine samples with a creatinine
concentration of 0.3 – 3 g/L should be used for case-by-case
Let’s calculate a creatinine clearance for a male based on the following
Assessment
data:
This essentially reflects the creatinine excretion rate of the adult
working population and is suitable mainly as a criterion for assessing
UV X 1.73
occupational exposure.
P
A
Creatinine excretion is significantly lower particularly in children and
the elderly which makes
it likely that urine samples with creatinine concentrations below 0.3
U=concentration of creatinine is 3 g/L (remember to change this to g/L occur very frequently.
mg/dL by multiplying by 100) U= 3g/L X 100=300 mg/dL
For the adult male, the normal range is 0.6 to 1.2 mg/dl,
the adult female, with her generally lower muscle mass, the
P=creatinine concentration in plasma is 1.9 mg/dL
normal range is 0.5 to 1.1 mg/dL
V= 1400 mL collected in 24 hours (change the collection time to
minutes) (1400/1440 min= 0.972 mL/min)
A= Surface area where the height is 56 inches (change to centimeters)
and the weight is 189 lbs (change to kilograms) 56 inches X
2.54=142.24 cm.
189 lbs/2.2=85.9 kg
Plug the cm and kg into the online calculator to get 1.9
Let’s convert and calculate the creatinine clearance.
300 mg/dL X 0.972 mL/min X 1.73 = 139 mL/min creatinine clearance
1.9 mg/dL X 1.9
If normal values for a male is 97 to 137 mL/min, what can you
determine from the rate of clearance we calculated? Remember, a
lower than normal creatinine clearance indicates renal disease.
Clearance is often measured as milliliters/minute (ml/min). Normal
values are:


Male: 97 to 137 ml/min.
Female: 88 to 128 ml/min.
4. Work through related, contextual math-in-CTE examples.
UV
P
X 1.73
A
Clearance is often measured as milliliters/minute (ml/min). Normal
values are:


Male: 97 to 137 ml/min.
Female: 88 to 128 ml/min.
U=concentration of creatinine is 1 g/L (remember to change this to U=1 g/L X 100= 100mg/dL
mg/dL by multiplying by 100) U= 3g/L X 100=300 mg/dL
P=creatinine concentration in plasma is 0.5 mg/dL
V= 2000 mL collected in 24 hours (change the collection time to
minutes)
P= assigned as 0.5 mg/dL
V= 2000 mL/1440 min=1.39 mL/min
A= Surface area where the height is 48 inches (change to centimeters) A= 48 inches X 2.54=121.92 cm; 304/2.2= 138.2 kg
and the weight is 304 lbs (change to kilograms)
BSA=1.897 from online calculator
5. Work through traditional math examples.
Introduce the formula for miles per hour:
There are many different ‘rates’ that can be calculated:
MPH = D(distance) / T(time)
Miles per hour, production rates; delivery rates, how fast water flows.
Demonstrate examples, such as
Distance = 100 miles , Time = 4 hours
Distance = 12 miles, Time = 2 hours
Distribute worksheet ‘Element #5 – Rate practice sheet’ and
complete either as a large group, cooperative small groups, or
individually.
HW – Distribute the ‘Element #5 – Blank scenario sheet for students
to complete. Next lesson day, have students exchange papers and
complete each other’s scenario.
6. Students demonstrate their understanding.
Students will move to the Clinical Lab and discover that 4 of the
patients have ’24-hour urine samples’ that have been collected. Taped
to their foreheads are their weight and height. Beside each bed is a
worksheet for each patient to calculate creatinine clearance and the
possibility of renal failure. Correct AND incorrect urine sample
measurements could be used to demonstrate the effect on incorrect
reporting.
WHO recommended that only urine samples with a creatinine
concentration of 0.3 – 3 g/L should be used for case-by-case
Assessment
This essentially reflects the creatinine excretion rate of the adult
working population and is suitable mainly as a criterion for assessing
occupational exposure.
Creatinine excretion is significantly lower particularly in children and
the elderly which makes
it likely that urine samples with creatinine concentrations below 0.3
g/L occur very frequently.
Urine stimulant will be in tinted containers in ice. Students will take note
of amount in container and take that number and empty the last
specimen for calculation and take that number. Creatinine clearance For the adult male, the normal range is 0.6 to 1.2 mg/dl,
will be calculated with the correct and incorrect amount. Comparison of the adult female, with her generally lower muscle mass, the
normal range is 0.5 to 1.1 mg/dL
results to show the importance of accurate collection will be done.
(If a lab environment is not available, students could pair up with each Patient 1: U=1.5 g/L; V=2400 mL(correct) 1500 mL
having to weigh and measure the other, be given random urine sample (incorrect);P=1;BSA: 58 inches height, 175 lbs. Male client
amounts, then calculate the same creatinine clearance and the Patient 2: U=3.7 g/L; V=1200 mL (correct), 900 mL (incorrect); P= 3;
possibility of renal failure. Or, worksheets could be generated.)
BSA: 52 inches height, 160 lbs. Female client
Patient 3: U= 0.4 g/L; V= 3000 mL (correct), 2300 mL (incorrect),
P=1.8; BSA: 53 inches, 115 lbs. Female client
Patient 4: U=2.7 g/L; V= 1000 mL (correct), 800 mL (incorrect): P=5;
BSA: 69 inches, 190 lbs. Male client
7. Formal assessment.
Presentation of the above results to the class will be used for the formal
assessment.
NOTES