Parathyroid Hormone (PTH): What Your Result Means

What is Parathyroid Hormone (PTH)?

Parathyroid hormone (PTH) raises blood calcium by pulling it from bone, keeping it in the kidneys, and activating vitamin D. Because its job is to defend calcium, PTH must always be read WITH the calcium level — the pair tells the real story. High calcium normally silences PTH; high PTH alongside high calcium is the signature of parathyroid overactivity.

Typical reference interval: Normal intact PTH is commonly roughly 10–65 pg/mL, but the range is assay- and calcium-dependent — the meaningful interpretation always comes from pairing PTH with the calcium value (ideally ionized or albumin-corrected).. Laboratories differ — the interval printed on YOUR report always governs.

If your Parathyroid Hormone (PTH) is high

Common reasons Parathyroid Hormone (PTH) runs above the reference interval:

• Overactive parathyroid gland (primary hyperparathyroidism) — high PTH PRODUCING high calcium — the classic parathyroid problem, often from a benign gland tumor
• Vitamin D deficiency — without vitamin D the body cannot use calcium well, so PTH climbs to compensate — high PTH with normal/low calcium
• Kidney disease — damaged kidneys hold onto less calcium and activate less vitamin D, driving PTH up
• Calcium loss from bowel or kidney — GI malabsorption or excessive urinary calcium loss lowers blood calcium, triggering PTH rise
• Medications — lithium and some other drugs can raise PTH

If your Parathyroid Hormone (PTH) is low

Common reasons Parathyroid Hormone (PTH) runs below the reference interval:

• High calcium from other causes — sarcoidosis, some cancers, or too much calcium supplement suppress PTH — the underactive-gland pattern
• Parathyroid gland damage — low PTH with low calcium after neck surgery or radiation
• Magnesium imbalance — high magnesium can suppress PTH

Symptoms worth knowing

PTH itself causes no symptoms — the calcium imbalance does. High calcium feels like stones, thirst, fatigue, and brain fog ('stones, bones, moans, groans'); low calcium feels like tingling, cramps, and sometimes seizures. The hormone is the cause; the symptoms live in calcium.

What usually happens next

1. Always interpret PTH with calcium (and vitamin D where available) — the pair is the interpretation
2. High PTH + high calcium → typically a parathyroid evaluation, often including imaging of the gland
3. High PTH + low or normal calcium → vitamin D and kidney status are the usual next checks

Frequently asked questions about Parathyroid Hormone (PTH) results