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HelpOrder Code LABPTHFN Parathyroid Hormone, Fine-Needle Aspiration Biopsy (FNAB)-Needle Wash
Additional Codes
Mayo Test Code: PTHFN
EPIC Test Code: LABPTHFN
Reporting Name
PTH, FNAB, Needle WashUseful For
Discriminating thyroid tissue from enlarged parathyroid glands
Facilitating parathyroid localization prior to surgery
An adjunct to cytology examination of fine-needle aspiration specimens to confirm or exclude presence of parathyroid tissue in the biopsied area.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Fine Needle WashSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Fine Needle Wash | Frozen (preferred) | 30 days | |
| Refrigerated | 4 hours |
Reference Values
An interpretive report will be provided.
Day(s) Performed
Monday through Saturday
CPT Code Information
83970
Method Description
The saline needle-wash specimen is analyzed with the Elecsys PTH reagent. The Roche cobas assay for determining intact parathyroid hormone (PTH) employs a sandwich test principle in which a biotinylated monoclonal antibody reacts with the N-terminal fragment (1-37) and a monoclonal antibody labeled with a ruthenium complex reacts with the C-terminal fragment (38-84). Application of a voltage to the electrode then induces chemiluminescent emission, which is measured by a photomultiplier. The antibodies used in this assay are reactive with epitopes in the amino acid regions 26-32 and 37-42.(Package insert: Elecsys PTH, Roche Diagnostics; 05/2023)
For all samples with high concentrations of PTH, a dilution series is performed. A linear dilution excludes hooking and most major interferences. Samples that contain low PTH concentrations are spiked with exogenous PTH to identify possible interferences that may cause a false-low result.
Reject Due To
| Gross hemolysis | Reject |
| Gross icterus | OK |
Shipping Instructions
Send specimen frozen.
Necessary Information
The biopsied site of each specimen must be clearly identified in the Laboratory Information System and/or batch sheet.
Specimen Required
Patient Preparation: For 12 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
Collection Container/Tube: Plain, plastic, screw-top tube
Specimen Volume: 1 to 1.5 mL
Collection Instructions:
1. Needle wash specimens for analysis should be collected in conjunction with cytology specimens.
2. Have saline available prior to start of procedure. Saline is the only acceptable solution for needle washings.
3. After each fine-needle aspiration biopsy (FNAB) has been collected and the material in the needle has been expelled onto a slide for cytologic analysis, attach the used FNAB needle to an empty syringe.
4. Draw between 0.10 mL and 0.25 mL of saline up through the needle until the saline starts to fill the hub of the needle or end of the syringe.
5. Expel this fluid back through the needle into a separate plastic aliquot tube. This is the needle washing used for analysis.
6. Repeat steps 2 through 4 for each needle pass of the same biopsied site and empty into the same tube, accumulating a total of 0.5 mL to 1.5 mL of fluid to send to the laboratory. (If more than 1 site is biopsied, see Additional Information)
7. Inspect specimen for visible blood or tissue contamination:
 a. If bloody, centrifuge specimen and transfer supernatant to a new plastic aliquot tube (5-mL standard tube) to send to laboratory. The supernatant, not the cellular material, is used for analysis.
 b. If specimen is clear, centrifugation is not necessary.
8. Freeze within 2 to 4 hours of collection.
Additional Information:
1. If more than 1 site is biopsied, each washing material should be submitted on a separate tube and under a different order number.
2. A minimum of 0.5 mL is required for testing; however, the total collection volume should not exceed 1.5 mL. Sample volumes outside these parameters may be rejected.
3. Do not send saline control. This test has been validated to rule-out saline matrix effect.
Method Name
Electrochemiluminescence Immunoassay