PTH (Parathyroid Hormone)
A hormone that regulates calcium and phosphorus levels. Essential for diagnosing parathyroid disorders and bone metabolism issues.
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What is PTH?
PTH (parathyroid hormone) is produced by four small glands behind your thyroid. It's the master regulator of calcium levels in your blood.
When calcium drops, PTH rises to:
- Release calcium from bones
- Increase calcium absorption in kidneys
- Activate vitamin D to boost intestinal calcium absorption
When calcium is adequate, PTH decreases.
Normal Ranges
| PTH Level | Interpretation |
|---|---|
| 15–65 pg/mL | Normal (varies by lab) |
PTH must be interpreted alongside calcium levels — the combination reveals the diagnosis.
Why It Matters
Parathyroid Disorders
- High PTH + High Calcium = Primary hyperparathyroidism (parathyroid tumor or hyperplasia)
- High PTH + Low Calcium = Secondary hyperparathyroidism (response to vitamin D deficiency or kidney disease)
- Low PTH + Low Calcium = Hypoparathyroidism
Bone Health
Chronic PTH elevation pulls calcium from bones, increasing osteoporosis risk.
Kidney Stone Risk
Hyperparathyroidism increases calcium excretion in urine, raising kidney stone risk.
What Affects PTH
- Vitamin D deficiency raises PTH
- Kidney disease raises PTH
- Magnesium deficiency can suppress PTH