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Test Name:
Parathyroid Hormone, Intact, with Calcium, Blood
- SBMF No:
30076 - Performance Lab Name:
Automated Lab - Test Mnemonic:
PTH INTACT - ABN:
May be required – Medical Necessity - CPT Code:
82310; 83970 - Test Includes:
Intact PTH
Calcium, Total - Also Known As:
Intact PTH
PTH, Intact - Spec Type:
Plasma (EDTA) for PTH –Plus– serum for calcium - Spec Container:
2 tubes: Lavender top (EDTA) for PTH –Plus– Gold top (SST) or Red top (serum) tube for calcium - Alt Spec Type:
Whole blood (EDTA) for PTH –plus– serum for calcium, OR
Serum for PTH and calcium - Alt Spec Container:
Lavender top (EDTA) for PTH –plus– gold top (SST) tube or red top (serum) tube for calcium, OR
Red top (serum) tube for PTH and calcium - Pref Vol:
1.0 mL EDTA plasma –plus– 1.0 mL serum, OR
4.0 mL EDTA whole blood –plus– 1.0 mL serum, OR
2.0 mL serum divided into two 1.0 mL aliquots - Min Vol:
0.5 mL EDTA plasma –plus– 0.2 mL serum, OR
2.0 mL EDTA whole blood –plus– 0.2 mL serum, OR
0.7 mL serum divided into two aliquots: 0.5 mL frozen and 0.2 mL refrigerated - Fasting:
Yes - Spec Collect:
Routine venipuncture - Spec Process:
- Centrifuge EDTA whole blood for PTH 15 minutes
- – Transfer EDTA plasma to separate tube
– Mark tube as "PTH - Plasma"
– Refrigerate (up to 72 hours) or freeze - If PTH submitted as EDTA whole blood, refrigerate (up to 48 hours)
- If PTH sample and calcium are both collected in red top serum tube:
- – Clot 30 minutes
– Centrifuge 15 minutes
– Within 2 hours of collection, transfer serum to 2 separate tubes
– Label one tube as "PTH - Serum" and freeze
– Label second tube as "Calcium - Serum" and refrigerate
- Spec Store Transport:
Refrigerated (up to 72 hours) EDTA plasma PTH
Refrigerated (up to 48 hours) EDTA whole blood PTH
Frozen for serum PTH (or EDTA plasma PTH greater than 72 hours) - Spec Stability:
48 hours refrigerated (2-8°C) for EDTA whole blood or plasma
6 months frozen (-20°C) for EDTA plasma or serum - Spec Reject:
Whole blood PTH not received within 48 hours of collection
Plasma PTH refrigerated, but not frozen within 72 hours of collection
Serum PTH not removed from cells and frozen within 2 hours of collection - Spec Remarks:
When preferred EDTA sample is collected for PTH, also collect serum for calcium (calcium portion of test cannot be performed on EDTA sample)
Mark sample in transfer tubes appropriately as "Plasma" or "Serum" - Methodology:
Chemiluminescent Immunoassay (CLIA) - Use:
An important aid in the diagnosis of calcium metabolism disorders - Clinical Significance:
Parathyroid hormone (PTH) is formed in the parathyroid glands and secreted into the blood stream. Intact PTH consists of a single polypeptide chain containing 84 amino acids and has a molecular weight of approximately 9500 daltons.
The biologically active N-terminal fragment has a half-life of only a few minutes. Selective measurement of the (mainly) intact parathyroid hormone permits direct ascertainment of the secretory activity of the parathyroid glands.
PTH, together with vitamin D and calcitonin, brings about mobilization of calcium and phosphate from the skeletal system and increases the uptake of calcium in the intestine and the excretion of phosphate via the kidneys. The constancy of the blood calcium level is ensured by the interaction of PTH and calcitonin. The secretion of PTH is inhibited by high calcium concentrations and promoted by low calcium concentrations.
Parathyroid gland disorders lead to elevated or depressed blood calcium levels (hypercalcemia or hypocalcemia) brought about by a change in the secretion of PTH.
Detection of subfunctioning parathyroid glands (hypoparathyroidism) requires the use of a highly sensitive test in order to be able to measure PTH levels well below normal.
Hyperfunctioning of the parathyroid glands results in an increased secretion of PTH (hyperparathyroidism). Primary causes are adenomas of the parathyroid glands. In secondary hyperparathyroidism the blood calcium level is low as a result of other pathological states (e.g. vitamin D deficiency).
Today, great significance is attached to the determination of the PTH and calcium concentrations when assessing hyperparathyroidism.
The determination of PTH intraoperatively during adenoma resection in the parathyroid glands has also been reported. The interoperative determination of PTH enables the surgeon to assess the completeness of resection on the basis of the rapid fall in PTH.
- Reference Range:
- Parathyroid Hormone, Intact, with Calcium, Blood
- Normal range: 15-72 pg/mL with calcium values ranging from 8.2-10.4 mg/dL.
Patients with hypercalcemia of malignancy: from undetectable to 22 pg/mL with calcium values ranging from 10.5-17.6 mg/dL
Patients with hypoparathyroidism: from undetectable to 21 pg/mL with calcium values ranging from 6.3-8.5 mg/dL
Patients with primary hyperthyroidism: greater than 60 pg/mL with calcium values ranging from 10.4-17.6 mg/dL
Patients with renal failure: greater than 72 pg/mL with calcium values ranging from 6-12 mg/dL
Note: Because of the interplay between calcium and PTH levels in various parathyroid/calcium metabolism disorders, interpretation of PTH results should take the serum calcium concentrations into account.
- Day Run:
Sun-Sat (daily) - Time Run:
As received - Time Reported:
4 hours - Test Type:
HORMONE
