PTH blood test
Parathyroid hormone
In short
A typical adult PTH result is 10 to 65 pg/mL. A high PTH has to be read with calcium from the same draw. If calcium is in range or low, low vitamin D and kidney disease are the most common reasons. Always read your result against the range printed on your own report.
The hormone that tells the body to raise blood calcium.
PTH is made by four small glands in the neck, the parathyroid glands. When calcium drifts low, PTH rises to release calcium from bone and hold on to it in the kidneys. It is always read next to a calcium result from the same blood draw.
Is my PTH high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Adults | 10–65 | pg/mL |
| Adults | 1.1–6.9 | pmol/L |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your PTH is high
A high PTH has to be read with calcium from the same draw. If calcium is in range or low, low vitamin D and kidney disease are the most common reasons.
Common reasons
- Low vitamin D, which makes the glands work harder
- Not enough calcium from food, or poor calcium absorption
- Long-term kidney disease
- Some medicines, including some mood-stabilizing and bone-strengthening medicines
- An overactive parathyroid gland, usually a small non-cancerous growth, when calcium is also high
- Less often: a gut condition that blocks absorption, such as celiac disease
If your PTH is low
A low PTH is often the glands resting because calcium is already high for another reason. Less often, the glands themselves are not making enough.
Common reasons
- Large amounts of calcium or vitamin D from supplements
- Past surgery on the thyroid or parathyroid glands
- Very low magnesium, which stops the glands releasing the hormone
- Conditions such as sarcoidosis (an inflammatory disease) that raise calcium
- Less often: a cancer that raises calcium, which switches PTH off
What can throw it off
High-dose biotin supplements can make some PTH tests read falsely low.
Questions to take to your appointment
- 1Was my calcium checked from the same blood draw?
- 2Should my vitamin D and kidney function be checked too?
- 3Do my PTH and calcium results fit together?
Read together with
Doctors rarely read PTH alone. These usually sit next to it.
- CalciumA mineral that builds bones and keeps nerves and muscles working.
- Ionized calciumThe free, active part of the calcium in blood.
- Vitamin DThe main blood test of the body's vitamin D supply.
- PhosphorusA mineral that works with calcium to build bones and teeth.
- CreatinineA waste product from muscles that the kidneys clear.
Quick answers
What is the PTH blood test?
PTH (Parathyroid hormone): The hormone that tells the body to raise blood calcium. PTH is made by four small glands in the neck, the parathyroid glands. When calcium drifts low, PTH rises to release calcium from bone and hold on to it in the kidneys. It is always read next to a calcium result from the same blood draw.
What is a normal PTH level?
For most adults, PTH is typically 10 to 65 pg/mL. Some countries print it in pmol/L, so check the unit first. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high PTH mean?
A high PTH has to be read with calcium from the same draw. If calcium is in range or low, low vitamin D and kidney disease are the most common reasons. Common reasons include low vitamin D, which makes the glands work harder; not enough calcium from food, or poor calcium absorption; long-term kidney disease; and some medicines, including some mood-stabilizing and bone-strengthening medicines. A doctor reads it together with your other results and how you feel.
What does a low PTH mean?
A low PTH is often the glands resting because calcium is already high for another reason. Less often, the glands themselves are not making enough. Common reasons include large amounts of calcium or vitamin D from supplements; past surgery on the thyroid or parathyroid glands; very low magnesium, which stops the glands releasing the hormone; and conditions such as sarcoidosis (an inflammatory disease) that raise calcium.
What can affect my PTH result?
High-dose biotin supplements can make some PTH tests read falsely low.
What should I ask my doctor about my PTH?
Questions worth taking to the appointment: Was my calcium checked from the same blood draw? Should my vitamin D and kidney function be checked too? Do my PTH and calcium results fit together?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
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