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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):  Lt. Green/Lithium Heparin, Gold SST, Red, Dark Green/Sodium Heparin

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: 2 - 8 C

Storage location: Core 5 Chemistry Refrigerator  

Off-site collection: Spin blood within 2 hour of collection. Transfer serum/plasma to plastic aliquot container. Refrigerate if sent same-day by courier. 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

 

Performing Laboratory

Seattle Children's Laboratory    

 

Department

Department:  Core Chemistry

Phone Number: (206) 987-2617 (Client Services)

 

 

 

Synonyms

PTH

Availability

STAT Performed TAT
Y 24/7 1 h

 

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

9-88 pg/mL

CPT Codes

83970