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Test ID: PTHFN Parathyroid Hormone, Fine-Needle Aspiration Biopsy (FNAB)-Needle Wash

Reporting Name

PTH, FNAB, Needle Wash

Useful 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.

Clinical Information

Parathyroid hormone (PTH) is produced and secreted by the parathyroid glands, which are located along the posterior aspect of the thyroid gland. PTH analysis in rinse material obtained from fine-needle aspiration (FNA) biopsies has gained popularity to discriminate thyroid tissues from enlarged parathyroid glands as well as facilitate parathyroid localization prior to surgery. Various groups have reported on the utility of this technique with specificity of 91% to100% and sensitivity of 82% to 100%. Measuring PTH in the rinse material proves to be very useful in cases of nondiagnostic cytology. Comparing the results of the PTH rinse material with serum PTH is highly recommended. An elevated PTH in the serum could falsely elevate PTH in the washings if the rinse is contaminated with blood. In these cases, only PTH values significantly higher than the serum should be considered as true positive results.


Cytologic examination and measurement of PTH can be performed on the same specimen. To measure PTH, the FNA needle is rinsed with a small volume of normal saline solution immediately after a specimen for cytological examination has been expelled from the needle for a smear or CytoTrap preparation. Specimen collection is critical for the performance of the assay, and the needle should be rinsed with a minimal volume. Each FNA needle from a single biopsied area is washed with 0.1 to 0.5 mL of normal saline. The washes from a single area are pooled (final volume 0.5-1.5 mL). PTH levels are measured in the saline wash.


Parathyroid hormone (PTH) values less than 100 pg/mL suggest the biopsied site does not contain PTH-secreting tissue.


PTH values greater than or equal to 100 pg/mL are suggestive of the presence PTH-secreting tissue at the site biopsied or along the needle track. This result is dependent on accurate sampling and a total needle wash volume between 0.5 and 1.5 mL.


This test should be interpreted in the context of the clinical presentation, imaging, and cytology findings.


If the results are discordant with the clinical presentation, a sampling error at the time of the biopsy should be considered.

Report Available

1 to 3 days

Day(s) Performed

Monday through Saturday

Clinical Reference

1. Bancos I, Grant CS, Nadeem S, et al. Risks and benefits of parathyroid fine-needle aspiration with parathyroid hormone washout. Endocr Pract. 2012;18(4):441-449

2. Ketha H, Lasho MA, Algeciras-Schimnich A. Analytical and clinical validation of parathyroid hormone (PTH) measurement in fine-needle aspiration biopsy (FNAB) washings. Clin Biochem. 2016;49(1-2):16-21

3. Trimboli P, D'Aurizio F, Tozzoli R, Giovanella L. Measurement of thyroglobulin, calcitonin, and PTH in FNA washout fluids. Clin Chem Lab Med. 2017;55(7):914-925

Method Name

Electrochemiluminescence Immunoassay

Specimen Type

Fine Needle Wash

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.

Specimen Minimum Volume

1 to 1.5 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.

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
PTHFN PTH, FNAB, Needle Wash 88106-0


Result ID Test Result Name Result LOINC Value
PTHF PTH, FNAB, Needle Wash 88106-0
SITEA Site 39111-0
Mayo Clinic Laboratories | Endocrinology Catalog Additional Information: