Pathology Handbook

Parathyroid Hormone

Synonyms

PTH

Clinical Indications

Differential diagnosis of hypercalcaemia.
Assessment of parathyroid activity in patients with chronic renal failure.
Investigation and monitoring of patients with hyperparathyroidism secondary to vitamin D deficiency or malabsorption.
Investigation of hypocalcaemia.

Request Form

Request on ICE

Availability

On request, if specific criteria met.

Specific Criteria

Investigation of abnormal calcium status or monitoring renal bone disease.

Patient Preparation

Samples must only be collected at Southend Hospital

Calcium levels should be requested at same time.

Turnaround Time

Weekly

Specimen

EDTA plasma (Biochemistry EDTA) and a serum SST sample

Volume

2 ml

Container

Vacutainer lemon top

Vacutainer gold top

Collection

Samples should be transported to the laboratory as soon as possible after collection. 

Lab Handling

Sample must be separated and frozen as soon as possible after receipt

Causes for Rejection

Unlabelled sample.

Delay in sample reaching laboratory. Unnecessary repeat requesting.

Reference Range

1.05 - 6.83 pmol/L for normocalcaemic patients.

However, most patients are being investigated for abnormal calcium levels and in non-parathyroid disease PTH levels should reflect calcium status (i.e. high calcium, low PTH).
In the presence of hypercalcaemia, a clearly elevated PTH of >7.0 pmol/L is diagnostic of primary hyperparathyroidism, while an appropriately suppressed result of <2.6 pmol/L virtually excludes primary hyperparathyroidism but could be due to FBH.

Where the PTH is between 2.6 and 7.0 pmol/L, either primary hyperparathyroidism or FBH is possible.