Parathyroid Hormone (PTH) Test: Normal Range Explained

What Is Parathyroid Hormone?

PTH is produced by four small parathyroid glands in your neck. It regulates calcium, phosphorus and vitamin D levels in your blood and bones.

Normal PTH Range

What High PTH Means

What Low PTH Means

Hypoparathyroidism can result from gland damage during neck surgery, autoimmune disease or genetic conditions, leading to low calcium and symptoms like muscle cramps and tingling.

Symptoms of Abnormal PTH

• Bone pain or fractures
• Kidney stones
• Fatigue and weakness
• Muscle cramps or tingling (low calcium)
• Excessive thirst and urination (high calcium)

PTH vs calcium vs vitamin D vs phosphate: how they compare

PTH is never interpreted alone — it is read as a quartet with calcium, vitamin D and phosphate. Each answers a different question:

The classic patterns: high PTH with high calcium suggests primary hyperparathyroidism; high PTH with low calcium suggests secondary causes — vitamin D deficiency or kidney disease.

Reading your report: what your doctor actually looks at

When a doctor opens a PTH result, the calcium line is read first. Here is the checklist they run through — and the same checklist helps you read your own report calmly:

1. What is the calcium doing? PTH without calcium is uninterpretable — high PTH with high calcium and high PTH with low calcium are different diseases with different treatments.
2. What is vitamin D? Low vitamin D is the commonest reason for a raised PTH — secondary hyperparathyroidism that resolves with repletion. Check D before chasing glands.
3. Can PTH be high with normal calcium? Yes — normocalcaemic primary hyperparathyroidism exists, and early secondary causes show it too. Normal calcium modifies the interpretation; it doesn't end it.
4. What are the kidneys doing? Chronic kidney disease drives secondary (and eventually tertiary) hyperparathyroidism — kidney function is part of every PTH workup.
5. Is it actually parathyroid, not thyroid? Despite the name, PTH has nothing to do with thyroid hormone — the parathyroid glands are separate structures. Don't mix up the tests. Discuss the full picture with your doctor.

PTH is a pattern test: hormone plus calcium plus vitamin D plus kidneys. A single high value with low vitamin D is usually the deficiency, not the gland. Discuss the full picture with your doctor.

PTH test price in India: typical bands across major lab chains

Intact PTH is a specialised immunoassay, so it costs more than routine chemistry — and smaller centres may send the sample out. Typical list-price bands:

These are approximate bands, not quotes: prices change often and vary by city, and home collection can add a small fee. Where possible, choose a NABL-accredited lab, and remember the reference range printed on your own report is the one that counts.

Frequently Asked Questions

Pharmacist's practical notes

Several common medicines move calcium and therefore PTH — thiazide diuretics raise calcium, loop diuretics lower it, lithium raises PTH itself. A new abnormal PTH with a recent prescription change deserves a medication review before the parathyroid glands are blamed.

Vitamin D repletion is the commonest “treatment” for high PTH — but it should follow testing, not precede it, since supplementing before the blood draw obscures the baseline pattern. Test first, then correct, then recheck.

In India

Indian labs report PTH in pg/mL. The test typically costs &rupee;1,000–&rupee;2,000, though prices vary by city and lab — intact PTH is a specialised immunoassay, so smaller centres may refer the sample onward.

Where possible, choose a NABL-accredited lab. Vitamin D deficiency is widespread, making secondary high PTH the commonest pattern seen.

Interpreting PTH alongside calcium

PTH is almost never interpreted alone: it only becomes meaningful when read together with the calcium level taken at the same time. Four broad patterns are recognised, and each points in a different direction.

High calcium with high or inappropriately normal PTH indicates primary hyperparathyroidism, usually from a benign parathyroid adenoma. High calcium with suppressed PTH suggests a non-parathyroid cause such as malignancy. Low calcium with high PTH is the expected compensatory picture in vitamin D deficiency or chronic kidney disease. Low calcium with low PTH points to hypoparathyroidism, often following thyroid or parathyroid surgery.

References

Sources cited on this page. PubMed links open the original abstract.

1. Bilezikian JP, Brandi ML, Eastell R, et al. Guidelines for the management of asymptomatic primary hyperparathyroidism: fourth international workshop. J Clin Endocrinol Metab. 2014;99(10):3561–3569. PMID 25162665 · doi:10.1210/jc.2014-1413
2. Cusano NE, Cetani F. Normocalcemic primary hyperparathyroidism. Arch Endocrinol Metab. 2022;66(5):666–677. PMID 36382756 · doi:10.20945/2359-3997000000556
3. Muñoz-Torres M, Varsavsky M, Avillez T, et al. Primary hyperparathyroidism. Med Clin (Barc). 2017;149(12):530–536. PMID 28992983 · doi:10.1016/j.medcli.2017.07.020

The PTH-calcium relationship, the central regulating axis

Parathyroid hormone (PTH) and calcium are linked by a direct feedback loop: when blood calcium falls, parathyroid glands secrete PTH within seconds; when calcium rises, PTH is suppressed. This relationship is the key to interpreting any PTH result, the calcium level must be interpreted simultaneously:

• High PTH + high calcium = primary hyperparathyroidism (usually a single benign parathyroid adenoma secreting PTH autonomously, ignoring the normal feedback signal). This is the most common cause of hypercalcaemia in outpatients, asymptomatic hypercalcaemia found incidentally on routine blood tests is primary HPT until proven otherwise.
• High PTH + low or normal calcium = secondary hyperparathyroidism (the gland is working normally but being overstimulated by a chronically low calcium, most commonly in vitamin D deficiency, chronic kidney disease, or malabsorption). The parathyroids are responding appropriately to a deficiency, not behaving autonomously.
• High PTH + low calcium (after years of secondary HPT) = tertiary hyperparathyroidism (the glands have become autonomously hyperactive after years of stimulation, seen in long-standing CKD, particularly post-kidney transplant).
• Low PTH + high calcium = PTH-independent hypercalcaemia, the hypercalcaemia is coming from elsewhere: malignancy (PTHrP, PTH-related protein, from squamous cell lung cancer, renal cell cancer), vitamin D toxicity, sarcoidosis, or immobilisation. The suppressed PTH is appropriate, the parathyroids are working correctly but the high calcium is arising from a non-PTH source.

Primary hyperparathyroidism, management decisions

The majority of people with primary hyperparathyroidism found incidentally have only mildly elevated calcium and are asymptomatic.² The decision to operate (parathyroidectomy, curative surgery) versus observe depends on whether any of the following criteria are met (per international consensus guidelines):

• Corrected calcium more than 0.25 mmol/L above the upper limit of normal
• eGFR below 60 mL/min/1.73m²
• DXA T-score below −2.5 at any site, or vertebral fracture on imaging
• Age below 50
• 24-hour urine calcium above 10 mmol/day (increasing stone risk)

Parathyroidectomy is recommended in symptomatic patients regardless of calcium level. Preoperative imaging (sestamibi parathyroid scan, 4DCT, or ultrasound) localises the adenoma to guide minimally invasive surgery, which is now the standard approach with 95% cure rates and very low complication rates.