Test Code LAB108 Parathyroid Hormone, Intact
Clinical System Name
Parathyroid hormone (PTH)
Synonyms
PTH
Sample Requirements
Specimen: Whole blood
Container(s): Gold SST, Red, Dark Green/Sodium Heparin, Lt. Green/Lithium Heparin Microtainer, Lavender/EDTA
Preferred Vol: 2.0 mL
Minimum Vol: 1.0 mL
Note: Microtainers used for capillary collections are unacceptable. If a series of PTH are being drawn, use the same tube type for all collections.
Processing Instructions
Reject due to: capillary collections
Spin: Y
Aliquot: Y
Temp: - 20 C
Storage location: Spin blood within 2 hrs of collection; transfer a minimum of 0.5 mL serum/plasma to aliquot container. Freeze in CPA Freezer, Fz5 rack. If a calcium is ordered, it will print a separate calcium label. If sample is received frozen, do not thaw to assay calcium; it will be run when the PTH is assayed. Serum/plasma is stable for 48 hrs at 2 - 8 C on or off gel separator, and must be frozen for long term storage.
Off-site collection: Spin blood within 2 hour of collection. Transfer serum/plasma to plastic aliquot container. Serum or plasma is stable at 2 -8 C for 2 d on or off gel separator, but must be frozen for long term storage.
Stability
Specimen Type | Temperature | Time |
---|---|---|
serum/plasma | Room temp | 2 h |
Refrigerated | 2 d | |
Frozen | 6 m |
Availability
STAT | Performed | TAT |
---|---|---|
N | M - Sa | 1 - 3 d |
Contact the Chemistry Lab for requests outside of stated availability (206)987-2565.
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Chemistry
Location: Chem West
Phone Number: (206) 987-2617
CPT Codes
83970
Methodology
Method: "intact PTH" Chemiluminescent microparticle immunoassay (CMIA) by Abbott Alinity i
Analytical Volume: 0.3 mL serum/plasma
Limitations:
PTH exists as a single chain 84 amino acid polypeptide, numbered from the amino terminal. After secretion, PTH undergoes extensive fragmentation. Only the fragments that carry the amino terminus are biologically active. The half life of active PTH is approximately 5 minutes. Inactive PTH (large C-terminal; PTH 7-84) has a longer half-life; approximately 10 minutes, and smaller C-terminal fragments have even longer half lives. The Vitros 3600 assay uses a sandwich antibody technique; one antibody detecting PTH1-34, and a second antibody detecting PTH 39-84 with electro-chemiluminescent detection. This test and other immunoassays detect the intact PTH molecule (PTH 1-84), along with the large PTH fragment (PTH 7-84) that builds up in renal failure. Smaller PTH fragments and PTHrP do not cross react.
Reference Range
PTH transitioned platforms from Ortho Vitros 3600 to Abbott Alinity i on August 8, 2022.
There is a 30% positive bias with the new method.
9-88 pg/mL