Parathyroid Hormone (PTH)
Measures parathyroid hormone levels to assess calcium regulation and diagnose parathyroid gland disorders.
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This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
What this test measures
Parathyroid hormone (PTH) is produced by four small glands situated behind the thyroid in the neck, and it serves as the body's primary regulator of blood calcium levels. The parathyroid glands continuously monitor calcium concentration and respond to drops by releasing PTH, which restores calcium through three simultaneous mechanisms: signaling bones to release stored calcium into the bloodstream, increasing calcium absorption from food in the intestines, and reducing calcium loss through the kidneys.
PTH also influences phosphorus and vitamin D metabolism, both of which are intertwined with calcium balance. When PTH is abnormally high, it can accelerate bone loss by continuously pulling calcium from the skeleton. When PTH is abnormally low, blood calcium can fall to levels that impair nerve, muscle, and heart function. This test measures PTH concentration in the blood and is ordered to investigate abnormal calcium levels, evaluate parathyroid gland function, assess bone health, and help diagnose conditions like hyperparathyroidism (overactive glands) or hypoparathyroidism (underactive glands).
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals with abnormal calcium levels discovered on routine blood tests may need PTH testing to determine if parathyroid glands are functioning properly.
- Those experiencing symptoms of high calcium levels, such as fatigue, nausea, abdominal pain, kidney stones, or bone pain, should consider this test to evaluate potential hyperparathyroidism.
- Patients with symptoms of low calcium levels, including muscle cramps, tingling in fingers and toes, or muscle spasms, may benefit from PTH testing to assess for hypoparathyroidism.
- People with chronic kidney disease often require regular PTH monitoring as kidney dysfunction can affect calcium and phosphorus balance, leading to secondary hyperparathyroidism.
- Individuals with osteoporosis or unexplained bone loss may need PTH testing to rule out parathyroid disorders as an underlying cause of their bone health issues.
- Those with a family history of parathyroid disorders or multiple endocrine neoplasia syndromes should consider testing if they develop relevant symptoms.
What to expect
Preparation
No fasting is required for this test. Morning collection is often preferred as PTH levels can fluctuate throughout the day. Patients should inform the lab of any medications they are taking, particularly calcium or vitamin D supplements, as these may affect results.
Sample Type
A simple blood draw from a vein in the arm, typically taking less than five minutes. The blood is collected in a special tube and must be handled carefully as PTH is unstable at room temperature.
Collection
The healthcare provider will clean the injection site, insert a small needle to draw blood, and collect the sample in appropriate tubes. Patients may feel a brief pinch when the needle is inserted.
Turnaround
Results are typically available within 1-3 business days after the sample reaches the laboratory.
Understanding your results
The normal range for PTH is approximately 15 to 65 picograms per milliliter (pg/mL), though reference ranges vary by laboratory. PTH results carry limited meaning without a simultaneous calcium level, because the two are physiologically linked: the clinical significance of a given PTH concentration depends entirely on whether calcium is high, low, or normal at the same time. Elevated PTH with elevated calcium suggests primary hyperparathyroidism, while elevated PTH with low calcium may indicate a secondary response to vitamin D deficiency or kidney disease. Healthcare providers always interpret PTH alongside calcium, phosphorus, vitamin D, and kidney function markers to identify the underlying condition.
| Population | Reference Range | Notes |
|---|---|---|
| Adults | 15-65 pg/mL | Most commonly reported range, though some labs use 10-65 pg/mL |
Reference ranges may vary by laboratory and individual factors. Results should be interpreted by a healthcare provider in the context of your overall health.
What does a “Low” result mean?
If PTH levels are lower than normal and blood calcium level is also low, it may mean parathyroid glands can't make enough PTH. This is called hypoparathyroidism. About 3 out of 4 cases (75%) are from accidental damage to parathyroid glands from neck or thyroid surgery. Low PTH levels can also occur with certain genetic conditions or autoimmune disorders affecting the parathyroid glands.
What does a “High” result mean?
If PTH level is higher than normal, it's called hyperparathyroidism. Primary hyperparathyroidism is high PTH levels with high blood calcium levels, often meaning that a problem with parathyroid glands is causing them to make too much PTH. The most common cause is a benign tumor (not cancer) in one of the parathyroid glands, called a parathyroid adenoma. Secondary hyperparathyroidism may occur when PTH levels are high but calcium levels are low, often due to vitamin D deficiency, kidney disease, or malabsorption disorders.
Privacy & confidentiality
All PTH test results are completely confidential and protected under HIPAA regulations. Results are not shared with insurance companies or added to your medical records without your consent, and no insurance billing occurs with direct-pay testing.
Frequently asked questions
Related tests
Calcium
Essential companion test to PTH as calcium and PTH levels must be interpreted together
View TestVitamin D
Vitamin D deficiency can cause secondary hyperparathyroidism and affects calcium absorption
View TestPhosphorus
PTH regulates phosphorus levels, and phosphorus testing helps complete the bone metabolism picture
View TestMagnesium
Magnesium deficiency can impair PTH function and affect calcium metabolism
View TestRelated conditions
Last reviewed: April 2026
CPT Code: 83970
This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
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