Why are PTH and calcium tested together?

PTH is the hormone that controls blood calcium, so neither result makes full sense alone. A high PTH means one thing when calcium is high (often primary hyperparathyroidism) and another when calcium is low or normal (often secondary hyperparathyroidism from low vitamin D or kidney disease).

My calcium was high on a metabolic panel. Is this the next test?

It is a common next step, and Quest recommends intact PTH as the first test for working out calcium-related abnormalities. Your clinician will decide what follow-up you need based on the result.

Quest does not require fasting for this test, but some clinicians prefer a fasting sample. Water is fine either way.

Can supplements affect the result?

Calcium and vitamin D affect the very system this test measures, and high-dose biotin can interfere with some laboratory immunoassays. Tell your clinician what you take, and do not stop a prescribed medication without talking to your prescriber.

Does a high PTH mean I need surgery?

Not necessarily. High PTH has several causes, including low vitamin D and kidney disease, that are managed very differently. A clinician interprets the result with your calcium and other tests and decides on any next steps.

Why do I need two tubes?

PTH is measured in EDTA plasma (a lavender-top tube) and calcium in serum, so the phlebotomist collects both in the same visit. You only need one needle stick.

How fast will I get results?

Quest typically reports this test within 1-2 days after your samples reach the lab. Results appear in your private JustLabs dashboard.

Can I use my FSA or HSA, and does insurance cover it?

JustLabs is a cash-pay service: the test is $62, plus one flat $18 Lab & Physician Order Fee per order, and no insurance claim is filed. Lab tests are generally eligible for FSA and HSA funds, and JustLabs provides an itemized receipt you can submit, but check with your plan administrator to confirm.

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✨ General Health

Parathyroid Hormone (PTH, Intact) and Calcium Test

PTH + Calcium

Measures intact parathyroid hormone (PTH) and calcium from the same visit. Because PTH is supposed to rise when calcium falls and fall when calcium rises, reading the two together shows whether your parathyroid glands are responding the way they should.

Your four parathyroid glands, small glands in the neck behind the thyroid, make parathyroid hormone (PTH) to keep blood calcium in a narrow range. When calcium drops, PTH rises and pulls calcium from bone, increases absorption from food and tells the kidneys to hold on to calcium. When calcium is high, PTH should fall.

That is why the two are measured together. A PTH value on its own can be hard to read; what matters is whether it fits the calcium level. High calcium with a high or high-normal PTH points toward primary hyperparathyroidism. High PTH with normal or low calcium suggests secondary hyperparathyroidism, where the glands are reacting to something else, such as low vitamin D or kidney disease. Low PTH with low calcium suggests hypoparathyroidism, and high calcium with a low PTH suggests a cause outside the parathyroid glands.

Quest notes that intact PTH is the recommended first assay for sorting out calcium-related abnormalities. A common reason to order this test is a high calcium result on a routine metabolic panel.

Calcium is also included in the comprehensive and basic metabolic panels and the renal function panel on JustLabs; this test adds the PTH measurement that explains a calcium result.

Price

$62

All-in

$80

incl. $18 lab & physician fee

Results

1-2 business days

Fasting

Not Required

What's Measured

Parathyroid Hormone (PTH), Intact

Calcium

What This Test Measures

Intact parathyroid hormone (the full, active PTH molecule) in EDTA plasma by immunoassay, and total calcium in serum by spectrophotometry, both from the same blood draw.

Who Should Consider This Test

People with a high or low calcium result on a previous test, people with symptoms that can come with abnormal calcium (such as kidney stones, bone thinning, fatigue, frequent thirst or urination, or muscle cramps and tingling), people with low vitamin D or chronic kidney disease whose clinician monitors PTH, and people who have had neck or thyroid surgery and are being checked for parathyroid function.

Health Insights

Conditions Screened

Primary hyperparathyroidismSecondary hyperparathyroidismHypoparathyroidismHigh blood calcium (hypercalcemia)Low blood calcium (hypocalcemia)PTH monitoring in chronic kidney disease

Related Symptoms

Kidney stonesBone thinning or fracturesFatigueIncreased thirst and urinationConstipation or nauseaMuscle cramps or tinglingBone, joint or muscle aches

When to Get Tested

When a routine panel shows abnormal calcium, when symptoms suggest a calcium problem, or on the schedule your clinician sets for monitoring, for example in chronic kidney disease. Quest does not list fasting or a timed draw for this test, but your clinician may ask for one so that repeat results are comparable.

No fasting needed. How to prepare for your blood test →

Understanding Your Results

Your report shows intact PTH (pg/mL) and calcium (mg/dL), each with an age-based reference range; for adults 19 and older, Quest's PTH range for this test is 14-64 pg/mL. Quest's interpretive guide reads the pair together: normal PTH with normal calcium is normal parathyroid function; high calcium with normal-to-high PTH fits primary hyperparathyroidism; high PTH with normal-to-low calcium fits secondary hyperparathyroidism (often from low vitamin D or kidney disease); high PTH with high calcium can be tertiary hyperparathyroidism; low or low-normal PTH with low calcium fits hypoparathyroidism; and low or low-normal PTH with high calcium points to a cause outside the parathyroid glands. These are patterns, not diagnoses. Review your results with a clinician, who may repeat the test or add vitamin D, phosphorus, magnesium or kidney function tests.

What to Expect

After placing your order, we send it straight to Quest Diagnostics — there is no consent form to sign and no partner email to wait for. Your requisition is usually ready to download from your dashboard within about an hour, and you can book your blood draw at any Quest Diagnostics location.

The blood draw typically takes just a few minutes. Results are usually available within 1-2 business days and will appear in your secure JustLabs dashboard.

Our results include reference ranges and easy-to-understand indicators showing whether your values are within normal limits.

How much does the PTH + Calcium test cost?

The PTH + Calcium test costs $62 at JustLabs — $80 all-in, since the $18 lab & physician order fee is charged once per order, however many tests you add. The price is fixed before your blood draw; no insurance or doctor visit needed.