PTH (Parathyroid Hormone): Normal Range, Results & What They
Everything you need to know about PTH (Parathyroid Hormone): Normal Range, Results & What They test results, including normal ranges and what abnormal levels might mean.
Reference Range
Unit: pg/mLReference Range
Reference ranges vary by laboratory. Always consult your healthcare provider for interpretation of your specific results.
What is PTH?
Parathyroid hormone (PTH) is like the master thermostat for your calcium balance. Produced by four tiny parathyroid glands in your neck (behind the thyroid), PTH continuously monitors calcium levels in your blood. When calcium drops, PTH rises to pull calcium from bones, increase kidney calcium reabsorption, and activate vitamin D to enhance intestinal calcium absorption.
Think of PTH as your body's calcium emergency response system. Every cell in your body depends on calcium for proper function—your heart won't beat correctly, muscles won't contract, nerves won't fire without it. PTH exists to prevent calcium from falling too low, which would be catastrophic. It's willing to sacrifice bone calcium to keep blood levels in the safe range.
The parathyroid glands are remarkably sensitive to calcium. Even a 1% drop in blood calcium triggers PTH release. This tight regulation is why PTH and calcium must always be interpreted together—they exist in a push-pull relationship that reveals the underlying physiology.
The PTH-Calcium Dance
PTH and calcium have an inverse relationship: as one goes up, the other goes down. This pattern recognition is key to diagnosis. High PTH + high calcium = parathyroid tumor (overproduction). High PTH + low calcium = vitamin D deficiency or kidney failure (appropriate compensation). Low PTH + low calcium = damaged parathyroids (underproduction). Low PTH + high calcium = non-parathyroid cause (cancer, vitamin D excess).
Understanding Your Results
PTH is measured in picograms per milliliter (pg/mL). The interpretation depends entirely on calcium levels:
Understanding Your Results (pg/mL)
Perfect parathyroid function—normal calcium regulation
Standard reference range—usually appropriate
Elevated—interpret with calcium level
Markedly elevated—investigation needed
Severely elevated—often indicates parathyroid tumor
Suppressed—interpret with calcium level
Why PTH Levels Change
Abnormal PTH reflects problems with calcium sensing, regulation, or parathyroid function:
Causes of Abnormal PTH
| Factor | Effect | What to Do |
|---|---|---|
| Primary hyperparathyroidism (parathyroid adenoma) | Increases | Benign tumor of parathyroid gland produces PTH autonomously, regardless of calcium levels. Causes high calcium with high or inappropriately normal PTH. Symptoms: kidney stones, osteoporosis, fatigue, depression, abdominal pain. Diagnosis: high calcium with high PTH. Treatment: parathyroid surgery (mini-parathyroidectomy) is often curative. Preoperative localization (sestamibi scan, ultrasound) guides surgery. |
| Vitamin D deficiency | Increases | Low vitamin D causes intestinal calcium absorption to drop, blood calcium falls slightly, PTH rises to compensate (secondary hyperparathyroidism). PTH pulls calcium from bones, maintaining blood calcium at expense of bone density. Long-term consequence: osteoporosis. Treatment: vitamin D supplementation (cholecalciferol D3) with adequate calcium intake. PTH normalizes as vitamin D repletes. |
| Kidney failure (chronic kidney disease) | Increases | Kidneys activate vitamin D and excrete phosphate. CKD causes low active vitamin D, phosphate retention, and low calcium. These all trigger PTH elevation (secondary hyperparathyroidism). Long-term consequence: renal osteodystrophy (bone disease from CKD). Treatment: active vitamin D (calcitriol), phosphate binders, calcium supplements, eventually dialysis. Nephrology management essential. |
| Hypoparathyroidism (parathyroid damage) | Decreases | Parathyroid glands damaged or removed, causing insufficient PTH production. Most common cause: neck surgery (thyroidectomy, parathyroidectomy). Also autoimmune, genetic. Result: low calcium, high phosphorus. Symptoms: tingling, muscle cramps, seizures. Treatment: calcium supplements and active vitamin D (calcitriol). Lifelong treatment usually required. |
| Vitamin D excess or intoxication | Decreases | Excessive vitamin D increases calcium absorption, raising blood calcium and suppressing PTH. Causes: overly aggressive supplementation, granulomatous diseases (sarcoidosis, TB) which activate vitamin D. Symptoms: high calcium symptoms (nausea, confusion, kidney stones). Treatment: stop vitamin D, possibly steroids, hydration. PTH recovers as calcium normalizes. |
Always tell your doctor about medications, supplements, and recent health events before testing.
The PTH-Calcium Patterns
PTH and calcium patterns reveal specific diagnoses:
When PTH Patterns Guide Diagnosis
Specific PTH patterns combined with calcium reveal different conditions:
PTH Patterns and Their Meaning
PTH must always be interpreted with calcium, vitamin D, phosphorus, and clinical context.
High calcium with high or inappropriately normal PTH
Primary hyperparathyroidism. Parathyroid gland (usually adenoma) produces PTH autonomously despite high calcium feedback. This is inappropriate—PTH should be suppressed with high calcium. Causes: single adenoma (85%), multi-gland hyperplasia (15%), rarely carcinoma. Parathyroid surgery often curative. Bone density and kidney function assessment needed.
Low or low-normal calcium with high PTH
Secondary hyperparathyroidism—appropriate PTH response to low calcium. Most common cause: vitamin D deficiency. Also kidney disease, malabsorption. PTH is trying to normalize calcium but can't completely compensate. Treatment: address underlying cause (vitamin D replacement, treat kidney disease). Don't remove parathyroids—they're responding appropriately.
Low calcium with low or inappropriately normal PTH
Hypoparathyroidism. Parathyroid glands aren't producing enough PTH. Usually from neck surgery complications, autoimmune, or genetic. PTH should be high with low calcium—inappropriately low/normal PTH indicates gland failure. Treatment: calcium and active vitamin D (calcitriol) replacement. Lifelong treatment usually required. Monitor for hypercalcemia from overtreatment.
High calcium with low PTH
Non-parathyroid hypercalcemia. High calcium from other causes suppresses PTH appropriately. Possibilities: malignancy (PTHrP production, bone metastases), vitamin D excess, granulomatous disease, medications (thiazides, lithium). PTH suppression confirms parathyroids aren't the cause. Treat underlying condition. PTH recovers when calcium normalizes.
Normal calcium, normal PTH, no symptoms
Normal parathyroid function. No specific action needed. Maintain adequate calcium intake (1000-1200 mg/day) and vitamin D sufficiency (30-60 ng/mL). If family history of parathyroid disease, periodic monitoring may be reasonable. Otherwise routine health maintenance.
Your Action Plan Based on Results
If your PTH is optimal (25-45 pg/mL) with normal calcium:
- Excellent parathyroid function
- Normal calcium regulation
- Maintain adequate calcium:
- Adults: 1000-1200 mg/day
- Food sources: dairy, leafy greens, sardines
- Maintain vitamin D sufficiency (30-60 ng/mL)
- No specific intervention needed
If PTH high with high calcium (Primary hyperparathyroidism):
- Medical evaluation recommended
- Possible parathyroid adenoma
- Comprehensive workup:
- Repeat calcium and PTH to confirm
- 24-hour urine calcium
- Bone density (DEXA scan)
- Kidney imaging (stones assessment)
- Parathyroid localization (sestamibi scan, ultrasound)
- Treatment options:
- Parathyroid surgery (curative in ＞95%)
- Monitoring if mild/asymptomatic
- Manage bone and kidney complications
- Surgical consultation typically recommended
If PTH high with low calcium (Secondary hyperparathyroidism):
- Appropriate PTH compensation
- Find and treat underlying cause:
- Check vitamin D level
- Assess kidney function
- Evaluate for malabsorption
- Treatment depends on cause:
- Vitamin D deficiency: repletion
- Kidney disease: calcitriol, phosphate binders
- Malabsorption: treat GI condition
- PTH normalizes when calcium normalizes
If PTH low with low calcium (Hypoparathyroidism):
- Parathyroid insufficiency
- Medical evaluation recommended
- Check:
- Magnesium level (low magnesium can cause transient hypoparathyroidism)
- Surgical history (neck surgery?)
- Autoimmune evaluation
- Treatment:
- Calcium supplements
- Active vitamin D (calcitriol)
- Possibly magnesium repletion
- Monitor:
- Calcium levels (avoid hypercalcemia)
- Kidney function
- Urine calcium
- Usually lifelong treatment required
If PTH low with high calcium:
- Non-parathyroid hypercalcemia
- Investigate underlying cause:
- Malignancy screening if indicated
- Review medications
- Check vitamin D level
- Consider granulomatous diseases
- Treat underlying condition
- PTH recovers when calcium normalizes
The Surgery Connection
Neck surgery (thyroidectomy, parathyroidectomy, neck dissection) can damage or remove parathyroid glands, causing hypoparathyroidism. Transient hypocalcemia is common post-thyroidectomy (10-30%), permanent in 1-3%. If you've had neck surgery and develop tingling, muscle cramps, or low calcium, check PTH. Post-surgical hypoparathyroidism requires calcium and calcitriol replacement, sometimes temporarily, sometimes permanently.
Common Questions
Track Your Parathyroid Hormone, Intact Results
Monitor your levels over time, identify trends, and share your history with your doctor.