Clinics and Departments

Laboratory Services

Lab Dept:


Test Name:


General Information

Lab Order Codes:



Fatty Acid, Stool; Fecal Fat Stain; Neutral Fat, Stool; Sudan Stain, Stool

CPT Codes:

82705 – Fat or lipids, feces; qualitative

Test Includes:

Microscopic examination using Sudan IV stain for screening for steatorrhea.


Lab Testing Sections:


Phone Numbers:

MIN Lab: 612-813-5866

STP Lab: 651-220-6555

Test Availability:

Daily, 24 hours

Turnaround Time:

Within 24 hours, test performed 0700-1530

Special Instructions:

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.


Specimen Type:

Fresh random stool


Plastic leakproof container


1 gram or 1 mL stool


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.


Refrigerate specimen if there is a delay greater than 2 hours. Do not send specimen through the pneumatic tube system.

Patient Preparation:

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.

Sample Rejection:

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.


Reference Range:

Neutral fat (before the addition of acid): <60 droplets/high power field (hpf)

Fatty acid (after addition of acid and heating): <100 droplets/hpf


Small amount of stool sample is diluted with 95% ethanol to elute fat. Sudan IV stain is added. Microscopic exam showing increased red-orange refractile fat globules identifies neutral fats. Fatty acids and fat soaps are detected after hydrolysis b y mixing the Sudan stained eluted stool sample with glacial acetic acid, followed by heating before microscopic examination. Microscopic exam of the acidified sample showing increased red-orange refractile fat globules identifies fatty acids.


Administration of barium, bismuth, Metamucil®, castor oil, or mineral oil within 1 week prior to collection of the specimen.


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

Miller, J Michael (1999) A Guide To Specimen Management in Clinical Microbiology, American Society for Microbiology, Washington DC

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


1/6/2014: Updated Methodology information.

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