Intact Parathyroid Hormone

Test Code
IPTH

Alias / See Also
Intact PTH

CPT Codes
83970

Specimen Container
Serum Seperator Tube (SST)

Preferred Specimen
Serum

Transport Temperature
Refrigerated

Specimen Stability

2 Days refrigerated
4 Weeks Frozen

Setup Days
Mon thru Friday

Methodology
Chemiluminescence

Reference Range
7.5-53.5 pg/mL

Clinical Use
Parathyroid hormone (PTH) is a single chain 84 amino acid polypeptide produced by the parathyroid gland. After PTH is secreted into the blood stream it undergoes extensive proteolysis to generate various fragments. In contrast to its degradation products, the concentration of Intact PTH is relatively independent of glomerular filtration rate and reflects the biologically active portion of the hormone.1 The primary role of PTH is to maintain calcium homeostasis via its interaction with calcitonin. PTH measurement is an important aid in the diagnosis of disorders of calcium metabolism. PTH synthesis and secretion are triggered rapidly by low concentrations of ionized calcium (Cai). The biological activities of PTH are to increase absorption of dietary calcium, decrease renal clearance and mobilize skeletal calcium stores. Abnormally high Cai concentrations suppress secretion of PTH.1 In conjunction with serum calcium levels, the PTH assay may be used as an aid in the differential diagnosis of hypercalcemia, hypocalcemia and parathyroid disorders. PTH determination is important in monitoring dialysis patients to manage renal osteodystrophy.
Guidelines from the National Academy of Clinical Biochemistry3 recommend the use of intraoperative parathyroid hormone testing for patients during surgery for hyperparathyroidism, especially in minimally invasive or directed procedures, as well as for patients undergoing reoperation. For patients undergoing parathyroidectomy it is recommended that preoperative and pre‑excision samples are taken. Samples should also be drawn at 5 and 10 minutes post resection and a >50% reduction in PTH levels from the highest baseline may be used as criteria for surgical success.