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Lab Dept:
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Urine/Stool
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Test Name:
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FECAL FAT, QUALITATIVE
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General Information
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Lab Order Codes:
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FAT
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Synonyms:
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Fatty Acid, Stool; Fecal Fat Stain; Neutral Fat, Stool; Sudan Stain, Stool
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CPT Codes:
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82705 – Fat or lipids, feces; qualitative
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Test Includes:
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Microscopic examination using Sudan IV stain for screening for steatorrhea.
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Logistics
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Lab Testing Sections:
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Microbiology
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Phone Numbers:
Minneapolis:
Saint Paul:
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612-813-5866
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651-220-6555
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Test Availability:
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Daily, 24 hours
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Turnaround Time:
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Within 24 hours, test performed 0700-1530
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Special Instructions:
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Requisition must state date/time of collection. A 72 hour quantitative fecal fat should not be ordered unless the qualitative fecal fat analysis is abnormal.
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Specimen
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Specimen Type:
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Fresh random stool
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Container:
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Plastic leakproof container
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Volume:
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1 gram or 1 mL stool
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Collection:
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Collect stool in a clean, dry bedpan or on a newspaper over the toilet. Transfer specimen to a plastic, leakproof container. Do not overfill or contaminate the outside of the container.
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Transport/Storage:
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Refrigerate specimen if there is a delay greater than 2 hours. Do not send specimen through the pneumatic tube system.
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Patient Preparation:
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Patient should be on diet containing at least 60 g of fat. The patient should not use suppositories or mineral oil before the specimen is collected. Oily material (e.g., creams, lubricants, etc) should be avoided prior to collection of the specimen.
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Sample Rejection:
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No diapers accepted. Improperly labeled specimen; specimen contaminated with urine and/or water; ≤0.5 grams stool; leaking container; insufficient volume; specimen containing interfering substances such as castor oil, bismuth, Metamucil®, barium, Vaseline®, or other cream contaminants. If an unacceptable specimen is received, the physician or nursing station will be notified and another specimen will be requested before the specimen is discarded.
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Interpretive
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Reference Range:
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Neutral fat (before the addition of acid): <60 droplets/high power field (hpf)
Fatty acid (after addition of acid and heating): <100 droplets/hpf
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Methodology:
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Small amount of stool sample is mixed with two drops of water, two drops of 95% ethanol, and three to four drops of Sudan IV stain. Increased yellow-orange refractile fat globules (direct Sudan IV stain) identifies neutral fats. Fatty acids and fat soaps are detected after hydrolysis by mixing stool sample with two to three drops each of Sudan IV and glacial acetic acid, followed by heating before microscopic examination.
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Contraindications:
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Administration of barium, bismuth, Metamucil®, castor oil, or mineral oil within 1 week prior to collection of the specimen.
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References:
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Cook, JH, and M Pezzlo (1992). Specimen receipt and accessioning. Section 1. Aerobic bacteriology, 1.2.1-4. In HD Isenberg (ed) Clinical Microbiology Procedures Handbook. American Society for Microbiology, Washington DC
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Miller, J Michael (1999) A Guide To Specimen Management in Clinical Microbiology, American Society for Microbiology, Washington DC
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Miller, J Michael, and HT Holmes (1999) Specimen Collection, Transport, and Storage In PR Murray et al, (ed), Manual of Clinical Microbiology, 7th edition, American Society for Microbiology, Washington DC, pp 33-104
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