Calcitonin, Fine-Needle Aspiration Biopsy Needle Wash, Lymph Node
Use
This test is used as an adjunct to cytologic examination of fine-needle aspiration specimens in athyrotic individuals who have been treated for medullary thyroid carcinoma, to confirm or exclude metastases in enlarged or ultrasonographically suspicious lymph nodes. Measurement of calcitonin in the needle wash specimens can improve the evaluation of suspicious lymph nodes when the cytology results are nondiagnostic or indeterminate. A calcitonin level of 5.0 pg/mL or higher suggests the presence of metastatic medullary thyroid carcinoma in the biopsied lymph node.
Special Instructions
The biopsy site of each specimen is required and must be clearly identified in the LIS and/or batch sheet. Saline should be prepared before starting the procedure, as it is the only acceptable solution for needle washings. The material in the needle is expelled onto a slide for cytologic analysis before collecting the wash specimen by filling the needle with saline and expelling it into a separate tube. Each tube should contain washings from a single biopsy site, and the supernatant of centrifuged specimens should be used for analysis.
Limitations
Improper specimen collection and handling, and interfering substances may lead to inaccurate results. Biotin, HAMA, and heterophile antibodies can interfere with immunoassays. Samples contaminated with blood will have falsely elevated results; only results significantly higher than serum results should be considered true positive. High doses of biotin (>5 mg/day) can interfere with the assay. Samples with unusually high analyte concentrations could be subject to a high-dose hook effect, leading to false or incongruent results. The results depend on accurate sampling and a maximum needle wash volume of 1.5 mL.
New York Approved
Methodology
Immunoassay (ECLIA)
Biomarkers
LOINC Codes
- 75709-6
- 75709-6
- 39111-0
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Other
Volume
1 to 1.5 mL
Minimum Volume
0.5 mL
Container
Plain, plastic, screw-top tube
Collection Instructions
Needle wash specimens should be collected with cytology specimens. Ensure saline is available before starting. Expel FNAB material onto a cytology slide, then attach the needle to an empty syringe and withdraw 0.10 to 0.25 mL of saline through the needle. Expel into a separate tube; repeat for more washings from the same site. Centrifuge bloody specimens and transfer supernatant to a new tube.
Patient Preparation
Do not take multivitamins or dietary supplements containing biotin for 12 hours before the procedure.
Storage Instructions
Send specimen frozen.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 4 hours |
| Frozen | 7 days |