Laboratory: Clinical Biochemistry  (AUTOMATED)
Test Name:
PARATHYROID HORMONE (PTH) - (P)
Test Code: PTHY
Clinical Information:
Test Indications: Parathyroid hormone (PTH) is formed in the parathyroid glands located at the posterior aspect of the thyroid gland and is secreted into the blood stream. PTH, together with vitamin D and calcitonin, mobilizes calcium and phosphate from the skeletal system and increases calcium uptake in the intestine and excretion of phosphate by the kidney. The interraction of PTH and calcitonin ensures blood calcium homeostasis. Parathyroid gland disorders lead to hypercalcemia or hypocalcemia due to a change in PTH secretion. The test is therefore useful in the differential diagnosis of hypercalcemia disorders, hypoparathyoidism and primary, secondary and tertiary hyperparathyroidism.
Recommendations: Simultaneous calcium measurement is required for appropriate interpretation.
Patient Preparation Instructions: Multivitamins (45–125 µg biotin) or biotin-only supplements up to 1 mg per day do not interfere with this test.

High dose biotin therapy (>5 mg/day) must be discontinued at least 8 hours prior to testing.
 
 

Collection Devices:
Specimen Required:


Plasma: 2.0 mL
Pediatric Plasma: 0.2 mL

Specimen Stability:

Ambient: 2 days

Refrigerated: 3 days

Frozen: 6 months at -20oC (freeze only once)

Referral:
Plasma: 2.0 mL

Plasma must be transferred to an aliquot tube and stored/shipped

·        Refrigerated if off-site testing to be performed within 48 hours of collection

·        Frozen if testing to be performed after 48 hours

·        DO NOT ship whole blood

See #110-10-05 Serum / Plasma Separation Procedure & Transport

Requisition:
Reference Values:
Age

Male

Female

Units
0 – <1 m

0.7 – 6.3 

pmol/L
1 – <12 m

0.9 - 6.5

pmol/L
1 – 10 y

1.2 - 6.3

pmol/L
11 – 18 y

1.6 - 7.2

pmol/L
≥ 19 y

1.6 - 6.9

pmol/L

 

Effective March 11, 2024

Comment in LIS: Reference values are based on healthy, normocalcemic, vitamin D-replete individuals with normal renal function.

Conversion factors:

1 ng/L = 0.106 pmol/L

1 pmol/L = 9.43 ng/L

Method of Analysis: Roche Electrochemiluminescence
 

Availability:
Daily
See Also:
More Information:
Interpretation & Assay Interferences: This assay has 99% cross-reactivity to the biologically inactive carboxy-terminal PTH fragment 7-84. PTH fragments are primarily cleared by the kidney and accumulate in renal failure. Therefore, healthy population reference ranges do not apply in renal failure.