A parathyroid hormone (PTH) level above 65 pg/mL is generally considered high for most standard lab assays. The normal reference range falls between roughly 15 and 65 pg/mL, based on the 2.5th and 97.5th percentiles in healthy adults. But what counts as “high” shifts dramatically depending on your kidney function, calcium levels, and vitamin D status.
The Standard Reference Range
Most labs report normal intact PTH as approximately 15 to 65 pg/mL. That upper limit of 65 pg/mL has been validated across diverse populations, including both Black and white adults. A result above that range signals your parathyroid glands are producing more hormone than expected, but the number alone doesn’t tell the full story. Your doctor will almost always interpret your PTH alongside your blood calcium and vitamin D levels, because the combination of these results points to very different conditions.
It’s worth noting that different lab instruments can produce slightly different reference ranges. The two most common test types, intact PTH and bio-intact PTH, have nearly identical normal ranges in the general population. Still, always check the specific reference range printed on your lab report rather than comparing your number to ranges you find online.
High PTH With High Calcium
When PTH is elevated and blood calcium is also above normal (roughly 10.4 mg/dL or 2.6 mmol/L), the most likely explanation is primary hyperparathyroidism. This means one or more of your four parathyroid glands is overproducing hormone on its own, usually because of a benign growth called an adenoma. It’s one of the most common hormonal disorders, especially in postmenopausal women.
Diagnosis typically requires at least two separate blood draws showing the same pattern. If calcium is elevated but PTH is in the “normal” range rather than suppressed, that’s still suspicious. A healthy body should respond to high calcium by dialing PTH down to near zero. A PTH that stays in the normal or mildly elevated range when calcium is high is behaving inappropriately.
Surgery is recommended when calcium rises more than 1 mg/dL above the upper limit of normal, or when complications like kidney stones, bone thinning, or fractures develop. For patients with calcium levels at or above 11.4 mg/dL (2.85 mmol/L), referral to an experienced parathyroid surgeon is standard practice.
High PTH With Normal Calcium
Some people have persistently elevated PTH while their calcium stays completely normal. This is called normocalcemic hyperparathyroidism, and it often goes unrecognized. Diagnosis requires that both corrected calcium and ionized calcium measure within the normal range on at least two occasions spread over six months, while PTH remains above the upper limit.
Before this diagnosis can be made, your doctor needs to rule out the far more common reason PTH runs high with normal calcium: your body is compensating for something. Low vitamin D, poor calcium intake, certain medications, and kidney problems can all push PTH up without affecting calcium. These causes need to be excluded first, because the treatment is entirely different.
High PTH From Vitamin D Deficiency
This is probably the most common reason for a mildly elevated PTH result. When your vitamin D drops too low, your body can’t absorb enough calcium from food. Your parathyroid glands sense the dip and ramp up PTH production to pull calcium from your bones instead. This compensatory response is called secondary hyperparathyroidism.
Research shows that PTH levels reach their lowest point when vitamin D blood levels (measured as 25-hydroxyvitamin D) sit above 28 to 32 ng/mL (70 to 80 nmol/L). Below that threshold, PTH starts climbing. The fix is straightforward: correcting the vitamin D deficiency with supplementation usually brings PTH back down over weeks to months. If your PTH is mildly elevated and your vitamin D is low, that’s almost certainly where your doctor will start.
High PTH in Kidney Disease
Chronic kidney disease changes the rules entirely. Damaged kidneys can’t activate vitamin D properly, can’t clear phosphate efficiently, and can’t maintain normal calcium levels. The parathyroid glands compensate by producing dramatically more PTH, sometimes reaching levels in the hundreds or even thousands of pg/mL.
For people on dialysis (stage 5 kidney disease), clinical guidelines from KDIGO suggest maintaining PTH at roughly 2 to 9 times the upper limit of normal for the lab assay being used. With a standard upper limit of 65 pg/mL, that translates to a target range of approximately 130 to 585 pg/mL. Levels above 9 times the upper limit (above roughly 585 pg/mL) are associated with increased risk of death, as are levels that drop below 2 times normal. This is a very different benchmark than what applies to people with healthy kidneys.
After a kidney transplant, PTH often remains elevated. In one study of 849 transplant recipients, nearly 62% still had elevated PTH one year after transplant. About 1 in 5 developed tertiary hyperparathyroidism, where the parathyroid glands have been overworking for so long that they no longer respond normally even after kidney function improves. This was defined as PTH at or above 70 pg/mL combined with high calcium at the one-year mark.
What High PTH Does to Your Body
PTH’s main job is regulating calcium. It pulls calcium from bones, tells your kidneys to hold onto calcium, and activates vitamin D so you absorb more calcium from food. When PTH stays elevated for months or years, the constant calcium drain from bones is the biggest concern.
In mild cases, you may not feel anything at all. Many people with primary hyperparathyroidism are diagnosed through routine bloodwork and have no obvious symptoms. Others notice vague issues: fatigue, weakness, low mood, difficulty concentrating, constipation, or poor sleep. These symptoms overlap with many other conditions, which is one reason the diagnosis is frequently delayed.
In more severe or long-standing cases, the bone effects become measurable. Bone density scans in people with severe primary hyperparathyroidism have shown T-scores as low as -4.25 at the spine and -5.44 at the hip, well into the range of severe osteoporosis. Bone pain, fractures from minor injuries, and visible erosion of finger bones on X-rays can develop. Kidney stones are another classic complication, since all that extra calcium being filtered through the kidneys can crystallize.
Putting Your Number in Context
A PTH of 70 pg/mL means something very different in a 55-year-old woman with high calcium than it does in a 30-year-old with severe vitamin D deficiency or a dialysis patient. Here’s a rough framework:
- Mildly elevated (66 to 100 pg/mL): Often caused by low vitamin D, low calcium intake, or early parathyroid disease. Usually the first step is checking vitamin D and calcium levels.
- Moderately elevated (100 to 300 pg/mL): More likely to reflect primary hyperparathyroidism if calcium is also high, or significant vitamin D deficiency or kidney disease if calcium is normal or low.
- Severely elevated (above 300 pg/mL): Common in advanced kidney disease. In someone with normal kidney function, levels this high typically indicate significant parathyroid gland disease requiring treatment.
The single most important piece of information alongside your PTH result is your blood calcium level. Those two numbers together point toward a cause far more reliably than either one alone.