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Endocrine

Parathyroid hormone (PTH)

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The hormone of the parathyroid glands that raises serum calcium by acting on bone and kidney and promoting activation of vitamin D. It is always interpreted together with calcium, phosphate, vitamin D and renal function.

Reference interval

Conventional (pg/mL)SI (ng/L)
Adults15–65 pg/mL15–65 ng/L

Specimen: Plasma (EDTA) or serum, intact PTH assay · Conventional × 1 = SI

Causes of high values

Primary hyperparathyroidism (high calcium with raised or inappropriately normal PTH), secondary hyperparathyroidism (chronic kidney disease, vitamin D deficiency, low calcium intake), tertiary hyperparathyroidism, pseudohypoparathyroidism, lithium and thiazide effects.

Causes of low values

Hypoparathyroidism (post-surgical, autoimmune, congenital), hypercalcaemia not mediated by PTH (malignancy, vitamin D toxicity, sarcoidosis), severe hypomagnesaemia, hungry-bone states after parathyroidectomy.

Pre-analytical and method notes

A typical interval for intact PTH is about 15 to 65 pg/mL (1.6 to 6.9 pmol/L) and the value varies between assays. PTH is unstable at room temperature (EDTA plasma on ice is preferred), has a circadian rhythm with a night peak, and target values in chronic kidney disease are higher and follow KDIGO guidance. Reference intervals vary by laboratory, method and population; use the interval printed on the report.

Related calculators

References

  1. Williams Textbook of Endocrinology. Elsevier, 14th edition (2019) — Tier 3 (textbook)
  2. KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Disease: Improving Global Outcomes (2013) — Tier 2 (guidelines / primary literature)
  3. Rifai N, Horvath AR, Wittwer CT. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Elsevier, 6th edition (2018) — Tier 3 (textbook)

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