Parathyroid Hormone (PTH)
Test Overview
The Parathyroid Hormone (PTH) test measures the level of parathyroid hormone in the blood. PTH is produced by the parathyroid glands, located in the neck, and plays a crucial role in regulating calcium, phosphorus, and bone metabolism. PTH helps maintain proper calcium levels in the blood by controlling the release of calcium from bones, the absorption of calcium in the intestines, and the excretion of calcium by the kidneys. Abnormal levels of PTH can indicate issues with the parathyroid glands, kidneys, or bone metabolism.
Test Uses
- Evaluate calcium levels: The PTH test is often ordered alongside a calcium test to help identify the cause of abnormal calcium levels (either high or low).
- Assess parathyroid function: The PTH test helps assess the function of the parathyroid glands, which regulate calcium and phosphorus balance in the body.
- Diagnose parathyroid disorders: Abnormal PTH levels may indicate conditions such as hyperparathyroidism (overactive parathyroid) or hypoparathyroidism (underactive parathyroid).
- Monitor kidney disease: Chronic kidney disease can affect phosphorus and calcium levels and PTH regulation, leading to secondary hyperparathyroidism.
- Evaluate bone health: Since PTH regulates bone metabolism, abnormal PTH levels may be associated with bone diseases like osteoporosis or osteomalacia.
Parathyroid Hormone Test Results & Ranges
| Test Component: | Normal Range: | Abnormal (Possible Conditions): |
|---|---|---|
| Parathyroid Hormone (PTH) | Adults: 10–65 pg/mL | High PTH (Hyperparathyroidism): Can indicate primary hyperparathyroidism, chronic kidney disease, vitamin D deficiency, or malabsorption syndromes. Low PTH (Hypoparathyroidism): Can indicate hypoparathyroidism, calcium toxicity, or magnesium deficiency. |
Expected Turnaround Time
- Results Available: Typically within 1–2 business days.
Specimen Requirements
- Sample Type: Blood sample (venipuncture).
- Container: Serum separator tube (SST) or plain red-top tube for serum collection.
Collection Instructions
- Fasting: Fasting is generally not required for this test.
- Medications: Inform your healthcare provider about any medications or supplements you are taking, particularly calcium, vitamin D, or lithium, as these can affect PTH levels.
- Proper sample collection: To avoid false low PTH results, ensure that the blood sample is collected and handled properly, as prolonged tourniquet application or delayed processing can interfere with the results.
Test Details
Clinical Use: The PTH test is crucial for evaluating calcium and phosphorus metabolism in the body. Hyperparathyroidism (elevated PTH levels) can cause hypercalcemia (high calcium levels) and can lead to symptoms like bone pain, kidney stones, and weak muscles. Hypoparathyroidism (low PTH levels) can cause hypocalcemia (low calcium levels) and result in symptoms such as muscle cramps, tetany, or seizures. The test is often used to investigate abnormal calcium levels, bone diseases, and kidney function.
Limitations: PTH testing can be influenced by a variety of factors, including calcium levels, vitamin D status, kidney function, and medications. Abnormal PTH results should be interpreted alongside other tests, such as calcium, phosphorus, vitamin D, and creatinine levels, to get a complete picture of the patient’s health. Conditions such as chronic kidney disease can cause secondary hyperparathyroidism, where PTH is elevated as a compensatory response to low calcium levels.
The Parathyroid Hormone (PTH) test is essential for assessing parathyroid function, calcium metabolism, and bone health. Abnormal levels can indicate a variety of conditions related to parathyroid disorders, kidney disease, or bone metabolism. Further evaluation and appropriate management may be required based on the results.