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EOSINOPHILS, RANDOM URINE
MessageORDER AS A MISCELLANEOUS TEST
DO NOT SEND URINE TO PERFORMING LAB, GIVE URINE TO CORE LAB TO MAKE THE SLIDE.
DO NOT SEND URINE TO PERFORMING LAB, GIVE URINE TO CORE LAB TO MAKE THE SLIDE.
Test Code
EOSU1
CPT Codes
85999
Preferred Specimen
1 Unstained cytospin slide
Minimum Volume
1 SLIDE
Instructions
1. Collect a random urine specimen.
2. Centrifuge 10 mL of a random urine collection.
3. Pour off supernatant. Assess urine sediment for presence of white blood cells (WBC). If no WBC are seen, the eosinophil test cannot be performed. If WBC are present, prepare slides using the centrifuged sediment.
4. The unstained slide should be prepared within 2 hours of collection. Only an unstained slide will be accepted. Any other specimen, including the raw urine specimen, will be rejected.
5. Centrifuge urine in cytospin centrifuge at speed of 750 rpm for 5 minutes.
6. Slides need to be labeled with patient name and date of birth
7. Guidelines for slide preparation. Use the sediment to prepare slides as follows:
a. 150 mcL of sample for 1 to 3 WBC/high power field (hpf)
b. 100 mcL of sample for moderate to normal sediment (<50 cell/hpf)
c. 50 mcL of sample for heavier sediment (>50 cells/hpf)
d. 25 mcL for packed fields of sediment
2. Centrifuge 10 mL of a random urine collection.
3. Pour off supernatant. Assess urine sediment for presence of white blood cells (WBC). If no WBC are seen, the eosinophil test cannot be performed. If WBC are present, prepare slides using the centrifuged sediment.
4. The unstained slide should be prepared within 2 hours of collection. Only an unstained slide will be accepted. Any other specimen, including the raw urine specimen, will be rejected.
5. Centrifuge urine in cytospin centrifuge at speed of 750 rpm for 5 minutes.
6. Slides need to be labeled with patient name and date of birth
7. Guidelines for slide preparation. Use the sediment to prepare slides as follows:
a. 150 mcL of sample for 1 to 3 WBC/high power field (hpf)
b. 100 mcL of sample for moderate to normal sediment (<50 cell/hpf)
c. 50 mcL of sample for heavier sediment (>50 cells/hpf)
d. 25 mcL for packed fields of sediment
Transport Temperature
Ambient (preferred) 14 days
Specimen Stability
Ambient (preferred) 14 days
Refrigerated 14 days
​Frozen 14 days
Refrigerated 14 days
​Frozen 14 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Stained slides
Urine aliquot
Urine aliquot
Methodology
Hansel Stain
Setup Schedule
Monday through Sunday
Report Available
1 day
Reference Range
0%
Results of greater than 5% eosinophils are indicative of acute interstitial nephritis; results between 1% and 5% eosinophils are indeterminant.
Results of greater than 5% eosinophils are indicative of acute interstitial nephritis; results between 1% and 5% eosinophils are indeterminant.
Clinical Significance
Eosinophils are white blood cells that normally do not appear in urine. The presence of eosinophils in the urine is seen in acute interstitial nephritis, which is caused by an allergic reaction, typically to drugs.
Performing Laboratory
Mayo Clinic Laboratories
Last Updated: July 8, 2025
