Parathyroid Hormone Blood Test (PTH)

Parathyroid hormone (PTH) is a key regulator of calcium and phosphate balance in the body. Produced by the four small parathyroid glands situated behind the thyroid, PTH acts on the kidneys, bones, and intestines to keep blood calcium within a tightly controlled range. This test measures the level of PTH in a simple blood sample and is typically requested when calcium levels are abnormal, when there is suspicion of parathyroid disease, or when investigating bone health, kidney function, or unexplained fatigue and neuromuscular symptoms.

It is suitable for patients with high or low calcium results, those being investigated for primary hyperparathyroidism or hypoparathyroidism, individuals with recurrent kidney stones or reduced bone density, and anyone under follow-up for chronic kidney disease or vitamin D disorders. Because PTH works in close partnership with calcium, phosphate, and vitamin D, it is often interpreted alongside these markers for a complete clinical picture.

Biomarkers included

• Parathyroid hormone (PTH)

Why it matters

PTH sits at the centre of calcium homeostasis. An abnormal PTH result can reveal an overactive or underactive parathyroid gland, explain recurrent kidney stones, low bone density, or persistent fatigue, and guide your doctor toward the right diagnosis and treatment. Measuring PTH gives a direct window into how your body is managing calcium, helping to distinguish between parathyroid disease and other causes of calcium imbalance.