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Test Code PTH Parathyroid Hormone, Intact

Important Note

Microtainers are unacceptable.  Requests for add-ons must meet the strict processing requirements listed below.

Clinical System Name

Parathyroid Hormone, Bio-intact with CA

Sample Requirements

Specimen: Whole blood

Container(s): Gold SST, Red, Dark Green/Sodium Heparin

Preferred Vol: 2 mL

Minimum Vol: 1 mL


Note:  Microtainers are unnacceptable. If a series of PTH are being drawn, use the same tube type for all collections. 

Collect INTRAOPERATIVE PTH specimens in a DARK GREEN/SODIUM HEPARIN TUBE for expedited processing

Processing Instructions

Reject due to: gross lipemia, gross hemolysis, samples stored in gel separator tube.

Spin: Y

Aliquot: Y

Temp: - 20 C

Storage location: Spin blood within one hour 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 8 hrs at 2 - 8 C, and must be frozen for long term storage.


Off-site collection: Spin blood within 1 hour of collection. Transfer serum/plasma to plastic aliquot container. Freeze serum immediately. Serum or plasma is stable at 2 -8 C for 8 hrs, but must be frozen for long term storage.


Specimen Type Temperature Time
whole blood Room temp 1 h
serum or plasma Room temp 1 h
  Refrigerated 8 h
  Frozen  4 w



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




Reference Range

14-75 pg/mL


Method: 2nd generation "intact PTH" chemiluminescent immunoassay by VItros 3600

Analytical Volume: 0.3 mL serum/plasma

Limitations: Hemolysis or turbidity may affect results.


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.

CPT Codes