Guides
High Parathyroid Hormone (PTH): Causes and Bone Health
A high PTH is read together with calcium. If calcium is high, primary hyperparathyroidism is considered; if normal or low, vitamin D deficiency or kidney disease.
Translated from the Turkish original by DoktorClub. The Turkish version is the reference text; this English translation has not been separately reviewed by a physician. Read the Turkish original.
Key takeaway
The meaning of a high PTH depends on the calcium measured at the same time. According to the TEMD 2025 Osteoporosis and Metabolic Bone Diseases guideline, a high or unsuppressed PTH when calcium is high most often suggests primary hyperparathyroidism. When calcium is normal or low, a high PTH is mostly due to vitamin D deficiency or kidney disease. Both conditions can speed up bone loss. Evaluate your result against the reference range on your report.
Short Answer
The meaning of a high PTH depends on the calcium measured at the same time. According to the TEMD 2025 Osteoporosis and Metabolic Bone Diseases guideline, a high or unsuppressed PTH when calcium is high most often suggests primary hyperparathyroidism. When calcium is normal or low, a high PTH is mostly due to vitamin D deficiency or kidney disease. Both conditions can speed up bone loss. Evaluate your result against the reference range on your report.
How does it appear on your report?
On reports, this test is written as "Parathormone (PTH)", "intact PTH" or "iPTH". In the Turkish Ministry of Health's Test Measurement Units list, the unit for PTH is ng/L. Many reports use pg/mL; the two are numerically the same.
Do not read PTH on its own. Also look at these values on the same report:
- Calcium: Total calcium is given in mg/dL, ionized calcium in mmol/L.
- Albumin: If albumin is low, total calcium may be misleading.
- 25-hydroxy vitamin D: Listed in µg/L in the national list; this is numerically the same as ng/mL.
- Phosphorus and creatinine (eGFR): Help distinguish kidney-related causes.
According to TEMD 2025, if albumin is low, corrected calcium is calculated. Formula: measured calcium + 0.8 × (4 − albumin). Your physician does this calculation.
The "Tahlillerim" (My Tests) screen in e-Nabız (Türkiye's national health record app) shows results with their reference values and marks out-of-range values in color. You can follow the trend of PTH and calcium with the chart icon.
Critical value: According to the Ministry of Health procedure, a total calcium of 6.5 mg/dL or below, or 13.0 mg/dL or above, is a critical value. In this case, the laboratory must report the result to the relevant physician in a timely manner.
Normal value and reference range
| Test | Example value | Source |
|---|---|---|
| Intact PTH | 10–65 pg/mL (ng/L) | TEMD 2025 |
| Total calcium (healthy adult) | 8.6–10.4 mg/dL (2.15–2.60 mmol/L) | TEMD 2025 |
| 25(OH) vitamin D | Below 20 ng/mL insufficiency; 20–50 ng/mL sufficient and safe | TEMD 2025 |
| 25(OH)D, for interpreting PTH | Preferably above 30 ng/mL | TEMD 2025 |
| iPTH in dialysis patients | About 2–9 times the upper limit of the test | KDIGO 2017 |
The PTH range varies by measurement method; the range on your report applies. The reference range covers 95% of healthy people; about 1 in 20 healthy people may fall slightly outside the range.
There are two different views on vitamin D. The Endocrine Society 2024 guideline does not recommend routine 25(OH)D testing in the healthy general population and does not define a target level. TEMD 2025, on the other hand, uses the thresholds above. When investigating a high PTH, measuring vitamin D is part of the evaluation according to TEMD.
What does it mean if it is high?
The causes are listed from common to rare.
1. Vitamin D deficiency (secondary hyperparathyroidism). The body raises PTH to preserve calcium. According to TEMD 2025, PTH was found to be high in 40% of people with a 25(OH)D level of 20 ng/mL or below, and in 51% of those below 10 ng/mL. In these people, bone loss accelerates and osteoporosis can develop.
2. Kidney disease. As kidney function declines, phosphorus builds up, vitamin D cannot be activated, and PTH rises. The KDIGO 2017 guideline recommends this monitoring from stage G3a of chronic kidney disease onward. According to KDIGO 2024, the abnormality must last longer than 3 months for a diagnosis of chronic kidney disease.
3. Medications. According to TEMD 2025, lithium can mimic the picture by affecting the calcium-sensing receptor. Tell your physician about the medications and supplements you use.
4. Familial hypocalciuric hypercalcemia. An inherited, usually harmless condition. Calcium is mildly high, and PTH is normal or mildly high. According to TEMD 2025, urine calcium is below 100 mg per day. Surgery is not needed in most cases in these people.
5. Normocalcemic primary hyperparathyroidism. According to TEMD 2025, PTH must be high at least 2 times, 3–6 months apart. Total and ionized calcium are normal. Secondary causes such as vitamin D deficiency and kidney disease must first be ruled out.
6. Primary hyperparathyroidism. One or more of the parathyroid glands produce too much hormone. The cause is one or more adenomas, gland enlargement or, very rarely, cancer. Diagnosis requires albumin-corrected calcium to be high twice, at least 15 days apart. According to TEMD 2025, its frequency in adults is 1–7 per 1,000, and most patients have no symptoms. Primary hyperparathyroidism and cancers account for 90% of cases of high calcium.
Does it cause osteoporosis? Yes, it can. According to TEMD 2025, in primary hyperparathyroidism bone loss is most marked in the forearm. That is why the forearm is also added to bone density measurement. In advanced cases, bone cysts and fractures can develop. After surgery, the drop in bone density improves. A high PTH due to vitamin D deficiency can also lead to osteoporosis. In kidney disease, both very high and very low PTH increase fracture risk.
When is surgery considered? TEMD 2025 uses the criteria of the 5th International Workshop in 2022. In asymptomatic primary hyperparathyroidism, surgery is considered if any of the following is present:
- Calcium exceeding the upper limit of normal by more than 1 mg/dL.
- A bone density T-score of −2.5 or below, or a vertebral fracture.
- eGFR below 60 mL/min, kidney stones or calcification in the kidney.
- Urinary calcium excretion above 250 mg per day in women or 300 mg in men.
- Being younger than 50 years.
When read together
- High PTH + high calcium: Primary hyperparathyroidism; 24-hour urine calcium distinguishes familial hypocalciuric hypercalcemia.
- High PTH + normal/low calcium + low vitamin D: Secondary hyperparathyroidism; PTH is repeated after vitamin D is corrected.
- High PTH + low eGFR + high phosphorus: Mineral and bone disorder due to kidney disease.
- High PTH + high ALP + very low vitamin D: Possibility of osteomalacia (softening of the bones).
- High PTH + mildly high calcium + low urine calcium: Familial hypocalciuric hypercalcemia.
- Low PTH + high calcium: The problem is not the parathyroid; causes such as cancer or vitamin D excess are investigated.
Preparing for the test
- Fasting and blood draw: According to TEMD 2025, calcium should be measured in the morning after an 8-hour fast. Blood should be drawn without applying a tourniquet to the arm.
- Repeat: High calcium is not accepted on a single measurement; it is confirmed by a repeat measurement.
- Biotin: According to TEMD 2025, biotin can make some PTH tests falsely low. A break of at least 48 hours before the PTH measurement is recommended; plan this with your physician.
- Tests to request together: To interpret PTH correctly, kidney function and the 25(OH)D level must also be known.
- Same method: According to KDIGO 2017, laboratories should report the measurement method and any change of method. If possible, have follow-up done at the same laboratory.
- Medications: Tell your physician about lithium, vitamin D and calcium supplements; do not stop them yourself.
Which doctor, which test?
- First step: Family physician or internal medicine; calcium, albumin, phosphorus, creatinine and 25(OH)D, with a repeat PTH.
- Endocrinology: If PTH is not suppressed while calcium is high, if PTH is persistently high, or if there is osteoporosis.
- Nephrology: If eGFR is low or chronic kidney disease is known.
- In primary hyperparathyroidism: 24-hour urine calcium, lumbar spine–hip–forearm bone density and kidney imaging.
- If surgery is planned: Ultrasound or scintigraphy to locate the gland; imaging is not recommended for diagnosis.
- Genetic counseling: Under age 30, with a family history of high calcium, or with involvement of more than one gland.
In Türkiye
- National guideline: The current edition of the TEMD Osteoporoz ve Metabolik Kemik Hastalıkları Tanı ve Tedavi Kılavuzu (Osteoporosis and Metabolic Bone Diseases Diagnosis and Treatment Guideline) is dated April 2025. It contains separate sections on primary hyperparathyroidism, vitamin D deficiency and bone disorders due to kidney disease.
- Vitamin D deficiency is common: According to TEMD 2025, the prevalence of vitamin D deficiency among adults in Türkiye is around 60%. In a meta-analysis including 40 studies conducted in Türkiye, this rate was found to be 63%. That is why a secondary cause frequently comes to mind with a high PTH.
- Critical values: The Ministry of Health's 2020 procedure considers total calcium of 6.5 mg/dL and below, and 13.0 mg/dL and above, as critical values.
- Units: In the national list, PTH is reported in ng/L, total calcium in mg/dL and ionized calcium in mmol/L.
- Difference from the foreign guideline: While the Endocrine Society 2024 does not recommend vitamin D screening in the general population, TEMD 2025 defines threshold values. Your physician determines which one applies to your situation.
When should you seek emergency care?
- If the laboratory has called you because of a critical calcium value, go to the emergency department the same day. According to TEMD 2025, people with calcium above 14 mg/dL should be treated urgently.
- If there is confusion, excessive sleepiness or irregular palpitations together with high calcium, call 112 (the emergency number in Türkiye).
- If there is excessive thirst, very frequent urination, vomiting and inability to take fluids, go to the emergency department the same day.
- If severe flank pain occurs together with fever or inability to urinate, go to the emergency department; it may be a kidney stone.
- If numbness around the hands, feet or mouth, muscle spasms or a seizure occur after parathyroid surgery, call 112.
Related lab tests
- Lab Test Guide: all tests
- What does low free T4 and T3 mean?
- High morning cortisol: stress or Cushing's?
- How to read a urine test
- How to interpret thyroid tests
What changed? (October 2026)
- The TEMD Osteoporosis and Metabolic Bone Diseases Guideline 2025 and the 2022 5th International Workshop surgery criteria were used as the basis.
- The Endocrine Society 2024 vitamin D guideline (no routine testing and no target level in the general population) was presented side by side with the TEMD 2025 thresholds.
- The KDIGO 2024 definition of chronic kidney disease and the KDIGO 2017 mineral–bone recommendations were added.
Sources
- Türkiye Endokrinoloji ve Metabolizma Derneği (TEMD). Osteoporoz ve Metabolik Kemik Hastalıkları Tanı ve Tedavi Kılavuzu. April 2025. https://file.temd.org.tr/Uploads/publications/guides/documents/OSTEPOROZ_nisan2025.pdf (accessed October 2, 2026)
- Turkish Ministry of Health, SHGM (T.C. Sağlık Bakanlığı SHGM). Karar Sınırı, Kritik Değer ve Ölçüm Birimlerinin Harmonizasyonu Prosedürü. 22.09.2020. https://dosyamerkez.saglik.gov.tr/Eklenti/15143/0/karar-siniri-esik-deger-kriek42009846pdf.pdf (accessed October 2, 2026)
- Turkish Ministry of Health, SHGM (T.C. Sağlık Bakanlığı SHGM). Test Ölçüm Birimleri, Versiyon 2. 15.09.2021. https://dosyamerkez.saglik.gov.tr/Eklenti/41467/0/test-olcum-birimleri-versiyon-2-pdfpdf.pdf (accessed October 2, 2026)
- Turkish Ministry of Health (T.C. Sağlık Bakanlığı). e-Nabız Kullanım Kılavuzu V2.1. 2025. https://enabiz.gov.tr/document/User_Manual.pdf (accessed October 2, 2026)
- Bilezikian JP et al. Evaluation and Management of Primary Hyperparathyroidism: Summary Statement and Guidelines from the Fifth International Workshop. J Bone Miner Res. 2022;37:2293-2314. https://doi.org/10.1002/jbmr.4677 (accessed October 2, 2026)
- KDIGO. 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of CKD-MBD. 2017. https://kdigo.org/guidelines/ckd-mbd/ (accessed October 2, 2026)
- KDIGO. 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. March 2024. https://kdigo.org/guidelines/ckd-evaluation-and-management/ (accessed October 2, 2026)
- Demay MB et al. Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2024;109:1907-1947. https://doi.org/10.1210/clinem/dgae290 (accessed October 2, 2026)
- Clinical and Laboratory Standards Institute (CLSI). EP28-A3c: Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory. 2010, reaffirmed in 2020. https://clsi.org/shop/standards/ep28/ (accessed October 2, 2026)
Frequently asked questions
Does high PTH cause osteoporosis?
Yes, it can. In primary hyperparathyroidism, bone loss is seen most in the forearm and can improve after surgery. A high PTH due to vitamin D deficiency also speeds up bone loss. That is why bone density measurement is requested when PTH stays high.
My PTH was high but calcium normal on e-Nabız; what does that mean?
The most common cause is vitamin D deficiency or reduced kidney function. First, 25(OH)D, creatinine and phosphorus are evaluated. If PTH remains high even though these causes have been corrected, normocalcemic primary hyperparathyroidism is investigated. According to TEMD 2025, this requires PTH to be high at least 2 times, 3–6 months apart.
My vitamin D is low and PTH high; will it improve if I take vitamin D?
In a high level with a secondary cause, PTH is expected to fall once vitamin D deficiency is corrected. To interpret PTH correctly, TEMD 2025 recommends raising the vitamin D level preferably above 30 ng/mL. PTH is then measured again. Only your physician determines the type and dose of supplement.
Does everyone need parathyroid surgery?
No. According to TEMD 2025, surgery is recommended in symptomatic primary hyperparathyroidism. In asymptomatic patients, calcium, bone, kidney and age criteria are considered. In the normocalcemic picture, no surgery recommendation is made because the data are insufficient.
I have kidney disease; why is my PTH high?
As kidney function declines, phosphorus builds up and vitamin D cannot be activated; this raises PTH. According to KDIGO 2017, the ideal PTH level in the pre-dialysis period is not known. With persistently rising PTH, correctable causes such as high phosphorus, low calcium and vitamin D deficiency are looked for.
