Test ID: PTHFN
Parathyroid Hormone, Fine-Needle Aspiration Biopsy (FNAB)-Needle Wash
NY State Approved 
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
An adjunct to cytology examination of fine-needle aspiration specimens to confirm or exclude presence of parathyroid tissue in the biopsied area
Method Name A short description of the method used to perform the test
Electrochemiluminescence Immunoassay
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Collection Container/Tube: Sterile vial
Submission Container/Tube: Plastic vial
Specimen Volume: 1-1.5 mL
Collection Instructions: After collection of the cytology specimens and expulsion of the material for smear or CytoTrap process as follows:
1. Wash/rinse each FNA needle from a single biopsied area with 0.1 to 0.5 mL of normal saline.
2. Pool each wash from a single biopsied area into 1 vial.
3. If more than 1 area is biopsied, each biopsy area should be submitted as a separate specimen under a separate order. Clearly identify each specimen.
4. Inspect the specimen as follows:
a. If the specimen shows visible blood or tissue contamination, centrifuge the specimen. Transfer the supernatant to a new plastic vial. Freeze specimen.
b. If specimen is clear, freeze specimen in plastic vial.
c. Specimen should be frozen within 4 hours of collection.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild reject; Gross reject |
| Lipemia | NA |
| Icterus | Mild OK; Gross reject |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Fine Needle Wash | Frozen (preferred) | 30 days |
| Refrigerated | 4 hours |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
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 biopsies (FNAB) has gained popularity to discriminate thyroid tissues from enlarged parathyroid glands and also to facilitate parathyroid localization prior to surgery. Various groups have reported on the utility of this technique with specificity of 91% to100% and sensitivity of 91% to 100%. Measuring PTH in the rinse material proved 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 positives.
Cytologic examination and measurement of PTH can be performed on the same specimen. To measure PTH, the fine-needle aspirate (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 1-1.5 mL). PTH levels are measured in the saline wash.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretive report will be provided.
Interpretation Provides information to assist in interpretation of the test results
Parathyroid hormone (PTH) values <100 pg/mL suggest the biopsied site does not contain PTH-secreting tissue.
PTH values > or =100 pg/mL are suggestive of the presence PTH-secreting tissue at the site biopsied or along the needle track.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test cannot distinguish between benign and malignant parathyroid tissue.
Immunometric assays can, in rare occasions, be subject to interferences such as "hooking" at very high analyte concentrations (false-low results) and heterophilic antibody interference (false-high results). If the clinical picture does not fit the laboratory result, these possibilities should be considered.
Results are dependent on accurate sampling and a maximum needle wash volume of < or =1.5 mL.
While the needle washes from several distinct needle passes or aspirations from a single area should be pooled, biopsies from different areas should be submitted as separate specimens.
Supportive Data
A retrospective review of Mayo Clinic parathyroid hormone analysis in fine-needle aspiration biopsy washings ordered clinically between June 2008 and May 2011 identified 42 specimens with confirmed parathyroid tissue (n=19) and nonparathyroid tissue (n=23). The assay showed 100% specificity and 74% sensitivity for the detection of parathyroid tissue using a value > or =100 pg/mL as positive.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Erbil Y, Salmaslioglu A, Kabul E, et al: Use of preoperative parathyroid fine-needle asipiration and parathyroid hormone assay in primary hyperparathyroidism with concomitant thyroid nodules. Am J Surg 2007;193:665-671
2. Owens CL, Rekhtman N, Sokoll L, Ali SZ: Parathyroid hormone assay in fine-needle aspirate is useful in differentiating inadvertently sampled parathyroid tissue from thyroid lesions. Diagn Cytopathol 2008 Apr;36(4):227-331
3. Giusti M, Dolcino M, Vera L, et al: Institutional experience of PTH evaluation on fine-needle washing after aspiration biopsy to locate hyperfunctioning parathyroid tissue. J Zhejiang Univ Sci B 2009 May;10(5):323-330
4. Kiblut N, Cussac J, Soudan B, et al: Fine needle aspiration and intraparathyroid intact parathyroid hormone measurement for reoperative parathyroid surgery. World J Surg 2004 Nov;28(11):1143-1147
Method Description Describes how the test is performed and provides a method-specific reference
The saline needle-wash specimen is analyzed with the Roche Diagnostics PTH reagent assay performed on the Roche Cobas 6000. 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(a) 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: Roche PTH reagent, Roche Diagnostics Corp, Indianapolis, IN July 2010)
For all samples with PTH concentrations >40 pg/mL, a dilution series is performed. A linear dilution excludes hooking and most major interferences. Samples that contain PTH concentrations <40 pg/mL are spiked with exogenous PTH to identify possible interferences that may cause a false-low result.
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 5 a.m.-12 a.m., Saturday; 6 a.m.-6 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
83970
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| PTHF | PTH, FNAB, Needle Wash | N/A |
| SITEA | Site | N/A |
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