Test Details
Methodology
Electrochemiluminescence immunoassay (ECLIA)
Result Turnaround Time
Within 1 day
Use
Diagnosis of parathyroid disease and other diseases of calcium homeostasis; monitoring patients undergoing renal dialysis
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Specimen Requirements
References
Custom Additional Information
PTH is an 84-amino-acid peptide hormone which is responsible for the regulation of serum calcium levels within a narrow range. PTH is secreted in response to decrease in serum calcium levels by increasing the renal reabsorption of calcium and lowering reabsorption of phosphorus. The measurement of PTH is a very useful tool in the differential diagnosis and management of hypercalcemia. PTH assays can be of help in the diagnosis of tumors and hyperplasia of the parathyroid gland, as well as in localizing hyperfunctioning parathyroid tissue by assay of samples obtained via venous catheterization. The native or intact (1-84) PTH has a short half-life, measured in minutes, whereas the carboxy and midmolecule fragments, which are biologically inactive, have half-lives 10- to 20-fold higher. The high concentrations of biologically inactive fragments have interfered with use of C-terminal or midmolecule assays for evaluation of parathyroid function in patients with impaired renal function. Intact PTH assays provide a more accurate assessment of parathyroid patients including those with various renal diseases.
Specimen
Plasma (preferred)
Volume
1.5 mL
Minimum Volume
0.7 mL (Note: This volume does not allow for repeat testing.)
Container
Lavender-top (EDTA) tube (preferable)
Storage Instructions
Refrigerate (preferable)
Causes for Rejection
Whole blood; plasma other than EDTA; hemolysis; room temperature or refrigerated serum
Collection Instructions
Transfer separated plasma into a plastic transport tube clearly labeled as "EDTA Plasma" and maintain at refrigerated temperature.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 2 days (stability determined by manufacturer or literature reference) |
Refrigerated | 3 days (stability determined by manufacturer or literature reference) |
Frozen | 6 months (stability determined by manufacturer or literature reference) |
Freeze/thaw cycles | Stable x1 (stability determined by manufacturer or literature reference) |
Reference Range
See table.1
Intact PTH (pg/mL) | Calcium (mg/dL) | Interpretation |
|---|---|---|
15−65 | 8.6−10.2 | Normal |
>65 | >10.2 | Primary hyperparathyroidism |
>65 | <10.2 | Secondary hyperparathyroidism |
<65 | >10.2 | Nonparathyroid hypercalcemia |
<15 | <8.6 | Hypoparathyroidism |
15−65 | <8.6 | Nonparathyroid hypocalcemia |
Footnotes
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 015610 | PTH, Intact | 2731-8 | 015610 | PTH, Intact | pg/mL | 2731-8 |
| Order Code | 015610 | |||||
| Order Code Name | PTH, Intact | |||||
| Order Loinc | 2731-8 | |||||
| Result Code | 015610 | |||||
| Result Code Name | PTH, Intact | |||||
| UofM | pg/mL | |||||
| Result LOINC | 2731-8 |