Fecal Fat Test (for detecting steatorrhea)

 



1. Objective

The objective of this test was to detect and measure the presence of excess fat in stool, aiding in the diagnosis of conditions causing steatorrhea (excess fat in feces), such as malabsorption syndromes, pancreatic insufficiency, or celiac disease.

2. Principle

Fat in stool was detected either qualitatively (e.g., by staining) or quantitatively. In the qualitative method, stool fat globules were stained using dyes like Sudan III or IV and observed microscopically. In the quantitative method, total fat excreted over a 72-hour period was measured gravimetrically after extraction and chemical treatment.

3. Materials

  • Fresh stool sample or 72-hour stool collection (for quantitative test)

  • Sudan III or IV stain (for qualitative test)

  • Microscopy slides and cover slips

  • Ethanol or acetic acid (for fat solubilization)

  • Glove, pipette, spatula

  • Analytical balance (for quantitative test)

  • Glassware and fat extraction solvents (for quantitative test)

4. Procedure

🧪 A. Qualitative (Sudan III Stain)

  1. A thin stool smear was prepared on a glass slide.

  2. A few drops of 95% ethanol were added to dissolve fat.

  3. Sudan III stain was applied, and the slide was covered and gently heated.

  4. The stained slide was examined under a microscope.

  5. Orange-red fat droplets indicated the presence of neutral fat.

🧪 B. Quantitative (72-hour Collection)

  1. The patient collected all stool for 72 hours on a controlled diet.

  2. Fat was extracted and quantified using chemical digestion and solvent extraction.

  3. The total grams of fat per day were calculated.

5. Result (Example)

Test TypeObservationInterpretation
Qualitative>60 fat globules per HPF (Sudan stain)Positive for steatorrhea
Quantitative12 grams/day (normal <7 g/day)Abnormal fat excretion

🧪 Example: Test was positive — Excessive fat present in stool, suggestive of steatorrhea.

6. Uses

  • Diagnosed conditions causing fat malabsorption:

    • Chronic pancreatitis

    • Celiac disease

    • Cystic fibrosis

    • Bile salt deficiency

  • Monitored response to pancreatic enzyme replacement therapy

7. Conclusion

The fecal fat test was a valuable diagnostic tool for detecting malabsorption syndromes, especially when steatorrhea was suspected clinically. Both qualitative and quantitative methods helped guide appropriate treatment decisions.

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