Fine and Ogunji developed a quantitative method for microscopically measuring fat in a feces. This generated a fecal fat droplet total size-number product, which shows a statistically linear correlation with chemically measured fecal fat output. The authors are from Baylor University in Dallas, Texas.
Method:
(1) Stool from a quantitative collection is homogenized.
(2) A 5 mm diameter sample is taken and mixed with 2 drops of 36% acetic acid and 2 drops of 1% Sudan III stain.
(3) The slide is placed over a hot plate until bubbles appear, and then it is removed. This is repeated for a total of 3 times.
(4) The slide is immediately examined at a magnification of 400x using an optical micrometer.
(5) Fields selected for counts show fat droplets but little if any opaque fecal debris.
(6) 5 fields are examined, counting the number of fat droplets fall into the following size ranges (see Table).
|
Size Range in microns
|
Average Size in Range
|
|
0 – 5
|
2.5
|
|
6 – 10
|
8
|
|
11 – 20
|
15.5
|
|
21 – 40
|
30.5
|
|
41 - 80
|
60.5
|
Fat particles > 80 microns are rare. For these:
(1) measure all of these globules in 5 microscopic fields
(2) calculate the average size
average number of fat particle in size range =
= (average count in 5 high dry microscopic fields)
weighted size-number product =
= (average size for range in microns) * (average number of fat particles in size range)
fecal fat droplet total size-number product =
= SUM(weighted size-number products for all size ranges)
Interpretation:
• minimum score: 0
• maximum score: > 4,000
|
Score
|
Significance
|
|
<= 200
|
normal range
|
|
201 - 475
|
mild steatorrhea
|
|
476 - 1,400
|
mild to moderate steatorrhea
|
|
1,401 - 2,400
|
moderate to severe steatorrhea
|
|
> 2,400
|
severe steatorrhea
|
from Figure 1 page 530
estimated fecal fat output in g per day (r = 0.89, P < 0.001) =
= (0.0303 * (product)) + 1.2
where:
• The slope of the line in Figure 1 is 0.303, but this gives too high a value when data is supplied.
Performance:
• The sensitivity is 94% and specificity of 95%.
Limitation:
• The measurement of the stool sample and the microscopic field selected for counting are sources of variability.
