Case Study: Plotting and interpreting BMI-for-age using the English system

A Case Study of ‘Charlene’

Step 1. Obtain accurate weights and stature measurements

Charlene, a girl, comes in for a visit.

Here is Charlene’s basic information:

Date of Birth (DOB): 10/30/96
Date of Visit (DOV): 11/5/00
Weight = 40 pounds 4 ounces
Height = 40 3/4 inches

Step 2. Select the appropriate growth chart

Based upon the above information, select a growth chart:


That’s incorrect. Please try again.

That’s correct!

Because Charlene is a normal 4-year old, a standing height was obtained. The appropriate chart to use is the ‘Girls 2 to 20 BMI-for-age’ chart.

Step 3. Record the data

The data entry table on the clinical growth chart can be completed with information relevant to the growth chart. Enter the missing data on the Data Entry Table and then click the ‘Submit’ button.

Charlene
Date of visit: 11/05/00
Child’s age: 4
Weight: 40 lbs 4 oz
Height: 40 3/4 inches

 

Step 4. Calculate BMI

Now calculate BMI at the time of Charlene’s clinic visit.

Date of visit: 11/05/00
Child’s age: 4
Weight: 40 lbs 4 oz
Height: 40 3/4 inches

Convert ounces and fractions to decimals:
Weight of 40 lbs and 4 oz = 40.25 lbs
(16 ounces = 1 pound, so 4 oz / 16 oz = 0.25)

Height = 40.75 inches

BMI = (weight / height / height) x 703

BMI = (40.25 lbs/40.75 in/40.75 in) x 703 = 17.0

Note: There is a difference of 0.1 between the BMI calculations when using the metric system (17.1) versus the English system (17.0). This is due to the conversion factor of 703.

Enter the BMI on the Data Entry Table and click ‘Submit’:

 Date of visit Age Weight Height BMI
11/05/00 4 lbs oz 40 3/4

That’s incorrect. Please try again.

BMI is incorrect. Please try again.

That’s right.

Step 5. Plot measurements

Charlene
Date of visit Age Weight Height BMI
11/05/00 4 40.25 40.75 17

All of the necessary information is recorded and Charlene’s BMI can be plotted. On the BMI-for-age chart, find Charlene’s age on the horizontal axis and visually draw a vertical line up from that point. Then find her BMI on the vertical axis and visually draw a horizontal line across from that point. The point where the two intersect represents Charlene’s BMI-for-age.

Click on the correctly plotted BMI-for-age chart from the three options below:

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Chart 1 showing BMI plotted just above 18 on the y axis and 4 on the x axis. Chart 1

Chart 2 showing BMI plotted at approximately 17 on the y axis and 3 on the x axis.Chart 2

Chart 3 showing BMI plotted at apporoximately 17 on the y axis and 4 on the x axis. Chart 3

That’s the correct chart!

When plotted on the growth chart, Charlene’s BMI-for-age falls between the 85th and 90th percentile curves.
Correct Chart!

Step 6. Interpret the plotted measurements

Since Charlene’s BMI-for-age falls between the 85th and 90th percentile curves, this means that of 100 children with the same gender and age as Charlene, 85 to 90 children will have a BMI-for-age lower than Charlene’s and 10 to 15 children will have a BMI-for-age greater than hers. Because Charlene’s BMI-for-age is above the 85th percentile, and lower than the 95th percentile, she is…


That’s incorrect. Please try again.

That’s correct!

Since Charlene’s BMI-for-age falls between the 85th and 90th percentile curves, she is overweight.

Congratulations! You have successfully calculated, plotted and interpreted Charlene’s BMI-for-age.

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