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Test Code LAB108 Parathyroid Hormone, Intact

Important Note

Microtainers used for capillary collections are unacceptable. 

Clinical System Name

Parathyroid hormone (PTH)



Sample Requirements

Specimen: Whole blood

Container(s): Gold SST, Red, Dark Green/Sodium Heparin, Lt. Green/Lithium Heparin Microtainer, EDTA/Lavendar

Preferred Vol: 2 mL

Minimum Vol: 1 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.


Specimen Type Temperature Time
serum/plasma Room temp 2 h
  Refrigerated 2 d
  Frozen  6 m



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:  Chemistry

Location: Chem West

Phone Number: (206) 987-2617




CPT Codes



Method: "intact PTH" Chemiluminescent microparticle immunoassay (CMIA) by Abbott Alinity i

Analytical Volume: 0.3 mL serum/plasma



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