Parathyroid Hormone
Also known as: PTH, Intact PTH
What Does Parathyroid Hormone Measure?
Parathyroid Hormone (PTH) is a protein hormone produced by the four small parathyroid glands located behind the thyroid gland in the neck. A blood test measuring PTH evaluates how much of this hormone is circulating in your bloodstream. The 'intact PTH' test specifically measures the full, biologically active form of the hormone, making it the most clinically useful version of the test. PTH levels are typically measured alongside calcium and sometimes vitamin D to give a complete picture of mineral metabolism.
Why Does Parathyroid Hormone Matter?
PTH is the master regulator of calcium and phosphorus balance in the body, working in concert with vitamin D and calcitonin to maintain stable blood calcium levels — which are critical for nerve function, muscle contraction, and bone health. When calcium levels drop, the parathyroid glands release PTH, which signals the bones to release calcium, tells the kidneys to retain calcium and excrete phosphorus, and stimulates the kidneys to activate vitamin D. Abnormal PTH levels can indicate serious conditions such as hyperparathyroidism, hypoparathyroidism, chronic kidney disease, or vitamin D deficiency. Because PTH directly drives bone resorption, chronically elevated levels can lead to osteoporosis and fractures, making it an important marker for long-term bone health.
Normal Ranges
Males
10–65 pg/mL (intact PTH)
Females
10–65 pg/mL (intact PTH)
Children
Varies by age; typically 10–65 pg/mL, but reference ranges differ by laboratory and pubertal stage
Causes of High Levels
- Primary hyperparathyroidism — a benign tumor (adenoma) on one or more parathyroid glands causes excess PTH secretion independent of calcium levels
- Secondary hyperparathyroidism — chronic kidney disease impairs calcium absorption and vitamin D activation, chronically stimulating PTH release
- Vitamin D deficiency — low vitamin D reduces intestinal calcium absorption, triggering compensatory PTH elevation
- Severe calcium deficiency or malabsorption — conditions like celiac disease or bariatric surgery reduce calcium availability, stimulating PTH
- Tertiary hyperparathyroidism — prolonged secondary hyperparathyroidism (often from kidney disease) causes the glands to become autonomous
- Pseudohypoparathyroidism — tissues resist PTH action, causing compensatory overproduction of the hormone
Causes of Low Levels
- Hypoparathyroidism — the parathyroid glands are damaged or removed during thyroid or neck surgery, producing too little PTH
How to Improve Your Parathyroid Hormone
Diet
- Ensure adequate calcium intake (1,000–1,200 mg/day from dairy, fortified plant milks, leafy greens, and canned sardines with bones) to reduce compensatory PTH stimulation
- Consume vitamin D-rich foods such as fatty fish (salmon, mackerel, tuna), egg yolks, and fortified dairy or cereals to support calcium absorption
- Include magnesium-rich foods (pumpkin seeds, spinach, black beans, almonds) as magnesium is required for proper PTH secretion and function
- Limit high-phosphate processed foods and colas, which can disrupt the calcium-phosphorus balance and chronically stimulate PTH
- Moderate excess animal protein and sodium intake, both of which can increase urinary calcium loss and reflexively raise PTH
Supplements
- Vitamin D3 (cholecalciferol): 1,000–4,000 IU/day (under physician guidance based on blood levels) — correcting deficiency is one of the most effective ways to lower an elevated PTH
- Calcium citrate or carbonate: 500–600 mg elemental calcium per dose (not to exceed 1,200 mg/day total from all sources) — best taken with meals for absorption
- Magnesium glycinate or citrate: 200–400 mg/day — supports PTH regulation and reduces risk of hypomagnesemia-induced PTH dysfunction
Related Biomarkers
Frequently Asked Questions
What does it mean if my PTH is high but my calcium is also high?
When both PTH and calcium are elevated simultaneously, this pattern is classic for primary hyperparathyroidism — a condition usually caused by a benign tumor (adenoma) on one of the parathyroid glands. Normally, high calcium should suppress PTH, so the fact that PTH remains elevated despite high calcium indicates the glands are not responding to feedback correctly. This condition requires evaluation by an endocrinologist and may be treated with surgery (parathyroidectomy) to remove the overactive gland.
Can high PTH cause osteoporosis?
Yes, chronically elevated PTH significantly increases the risk of osteoporosis and fractures. PTH stimulates osteoclasts — cells that break down bone — to release calcium into the bloodstream. When this happens persistently over months or years (as in untreated hyperparathyroidism), bones gradually lose density and become fragile. Bone density testing (DEXA scan) is often recommended for individuals with elevated PTH to assess fracture risk and guide treatment decisions.
What is the difference between primary, secondary, and tertiary hyperparathyroidism?
Primary hyperparathyroidism occurs when the parathyroid glands themselves malfunction (usually due to a benign tumor) and produce too much PTH regardless of calcium levels. Secondary hyperparathyroidism is a compensatory response — the glands are working correctly but are being driven hard because of low calcium, vitamin D deficiency, or chronic kidney disease. Tertiary hyperparathyroidism develops when secondary hyperparathyroidism goes on so long that the glands become autonomous and keep producing excess PTH even after the original trigger (like kidney disease) is treated.