Parathyroid hormone (PTH)
MedlinePlus gives 10 to 65 pg/mL for PTH. Studies that left out people with low vitamin D found upper limits near 46. PTH runs higher with low vitamin D and reduced kidney function, and assays differ widely. Higher PTH went with more cardiovascular events in cohorts. A trial of cinacalcet in dialysis did not significantly reduce deaths or cardiovascular events.
- Status
- A blood test ordered by a clinician and also sold direct to consumers by some US laboratories. FDA classifies parathyroid hormone test systems as class II devices [1]. A working group of the International Federation of Clinical Chemistry and Laboratory Medicine reports method-related differences of up to 5-fold between PTH assays [2].
- Measures
- The amount of parathyroid hormone in blood, a hormone released by the parathyroid glands that controls calcium, phosphorus and vitamin D levels [3].
- Also called
- PTH, parathyroid hormone, intact PTH, iPTH, PTH intact, parathormone, PTH blood test, serum PTH, parathyroid hormone intact molecule
- Tested for
- high calcium, low calcium, parathyroid problems, kidney disease, bone loss, osteoporosis, vitamin D deficiency, kidney stones
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Linked in research3
- ModerateLinked to higher PTH at lower vitamin D: 40% of people with 25-hydroxyvitamin D under 20 ng/mL had PTH above 65 pg/mL in 312,962 paired results.
- ModerateLinked to more cardiovascular events at higher PTH: 45% more in people with the highest levels than in those with the lowest across 10 cohorts.
- LimitedOne study found PTH differed across tenths of kidney function in 1,814 patients, and 12% of those with an eGFR above 80 already had high PTH.
Reported risks0
No risks sourced yet.
Reference ranges
Each range is the one its source published, in pg/mL. Also reported in pmol/L. Where sources differ, each is shown.
US National Library of Medicine, MedlinePlus
Adults, as a general range · [3], [4]
| Range | What the source calls it |
|---|---|
| below 10 pg/mL | No name given |
| 10 to 65 pg/mL | "normal" |
| above 65 pg/mL | No name given |
MedlinePlus states that ranges may vary slightly among laboratories, names no assay, and suggests using the same laboratory each time so results can be compared. It states that a value in the normal range can still be inappropriate when blood calcium is high, and that calcium is measured at the same time [3]. For the other unit, a Stockholm study converted results at 1 pg/mL to 0.106 pmol/L [4].
Souberbielle and colleagues, 2001, Allegro intact PTH assay, adults aged 60 to 79 with higher vitamin D
Adults aged 60 to 79 with 25-hydroxyvitamin D above 30 nmol/L, about 12 ng/mL · [5], [6]
| Range | What the source calls it |
|---|---|
| below 10 pg/mL | No name given |
| 10 to 46 pg/mL | "reference range" |
| above 46 pg/mL | No name given |
Printed as 10 to 46 ng/L, which is the same number in pg/mL, and described as a 95% interval. From 280 adults the study classed as healthy, 140 men and 140 women, sampled fasting in the morning from April through June. Of them, 59.6% had 25-hydroxyvitamin D of 30 nmol/L or below. Measured against this range, about 25% of the people with low vitamin D had a high PTH. The authors conclude that vitamin D status is to be taken into account when a PTH reference range is set in older people [5]. A later study of African American and white women with the same assay concluded the opposite, that the upper limit stays at 65 pg/mL (see that block) [6].
Souberbielle and colleagues, 2001, Allegro intact PTH assay, adults aged 60 to 79, whole group
Adults aged 60 to 79, whatever their vitamin D level · [5]
| Range | What the source calls it |
|---|---|
| below 13 pg/mL | No name given |
| 13 to 64 pg/mL | No name given |
| above 64 pg/mL | No name given |
Printed as 13 to 64 ng/L, the 95% interval in all 280 adults, most of whom had low vitamin D. The authors present it as the interval a laboratory gets when vitamin D is ignored, and argue for the narrower range above [5].
Touvier and colleagues, 2014, electrochemiluminescence immunoassay, adults with 25-hydroxyvitamin D of 20 ng/mL or above
Middle-aged adults with 25-hydroxyvitamin D of 20 ng/mL or above · [7]
| Range | What the source calls it |
|---|---|
| 45.5 or below pg/mL | "reference value" |
| above 45.5 pg/mL | "high" |
Printed as 45.5 ng/L, the 97.5th percentile. The abstract gives no lower limit. From 1,824 middle-aged Caucasian adults in a French cohort, with blood drawn in 1994. Among these vitamin D-replete adults the 97.5th percentile was 51.9 ng/L in those who were overweight or obese and 43.5 in those of normal weight. The authors note that the assay maker's upper limit was 65 ng/L [7].
Aloia and colleagues, 2006, Allegro intact PTH assay, women aged 20 to 80
Women aged 20 to 80 · [6]
| Range | What the source calls it |
|---|---|
| 65 or below pg/mL | "reference range" |
| above 65 pg/mL | No name given |
The study asked whether the upper limit for this assay ought to be lowered from 65 pg/mL to a proposed 46, and concluded that it stays at 65, because many values in its 503 African American and white women lay above 46. The abstract prints no lower limit. PTH was higher in Black than in white women, and rose with body mass index, age and serum creatinine and with lower calcium intake and lower 25-hydroxyvitamin D [6].
What has been shown to move it
Shown to lower it4
Phosphate and parathyroid hormone
Shown to lower blood phosphate, urea and parathyroid hormone in adults with chronic kidney disease on a protein-restricted diet.
In 17 RCTs, they lowered serum phosphate and parathyroid hormone.
The numbers and sources
- Effect
- Ketoanalogues added to a protein-restricted diet lowered blood urea nitrogen and phosphorus and raised calcium against a low-protein diet alone [1]. In 17 RCTs, they lowered serum phosphate and parathyroid hormone [2].
- Population
- Adults with CKD not on dialysis [1][2].
- Sources
- [1], [2]
- Caveats
- These are blood markers, not fractures or heart events.
Vitamin D levels
Shown to raise blood vitamin D in trials of UV and sunlight exposure. Advised sunlight raised it less than vitamin D supplements in one trial.
Compared with before the exposures, in the same people [1]; different UVB doses and skin areas [2]; vitamin D3 800 IU daily or 100,000 IU every 3 months [3]; care homes with no added sunlight [4]
Parathyroid hormone fell in all groups after 3 months, less with sunlight.
The numbers and sources
- Effect
- After simulated summer sunlight three times a week for 6 weeks in winter, 90% of adults reached a 25-hydroxyvitamin D level of 20 ng/mL and 26.2% reached 32 ng/mL [1]. The rise in 25-hydroxyvitamin D grew with UVB dose and, at small doses, with the area of skin exposed, and was smaller when the starting level was higher [2]. In vitamin D-deficient immigrants, advice to get sunlight raised 25-hydroxyvitamin D from 22.5 to 29.1 nmol/L over 6 months, against 53 nmol/L with 800 IU a day. Parathyroid hormone fell in all groups after 3 months, less with sunlight [3]. In frail older people, extra morning sunlight raised 25-hydroxyvitamin D only slightly, with a median adherence of 26% [4].
- Population
- 120 white adults aged 20 to 60 in Manchester, UK [1]. 92 participants [2]. 211 non-western immigrants aged 18 to 65 with a level under 25 nmol/L in the Netherlands [3]. 602 care home residents aged 70 and older, mean 86.4, in Sydney [4].
- Sources
- [1], [2], [3], [4]
- Caveats
- Two trials used UV lamps, not the sun [1][2]. Advice to go outdoors depends on whether people follow it [3][4]. Skin color, latitude, season and clothing change how much vitamin D the same time in the sun makes.
Long-term use
One small study: over 36 months on calcium AKG, blood calcium rose and parathyroid hormone fell in 14 dialysis patients. No long-term study in healthy people was located.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- In 14 hemodialysis patients given calcium AKG, a mean 4.5 g a day for 36 months, serum phosphate fell from 2.6 to 1.9 mmol/l, serum calcium rose from 2.2 to 2.47 mmol/l, and intact parathyroid hormone fell from 29 to 8 pmol/l [12]. The abstract does not report adverse events [12].
- Population
- 14 adults on hemodialysis [12].
- Sources
- [12]
- Caveats
- One uncontrolled study in kidney failure, where the falls in phosphate and parathyroid hormone were the aim of treatment [12]. It does not show what years of use do in healthy people.
Bone density and growth in children
One small trial in children found lower bone density gains on topiramate, with 21% losing a clinically important amount against none on the comparison drug, and slower weight gain.
Serum parathyroid hormone and 25-hydroxyvitamin D fell, and urinary calcium rose.
The numbers and sources
- How common
- Very common: more than 1 in 10 people.
- Effect
- In a one-year active-controlled trial, topiramate lowered lumbar spine and whole-body bone mineral density, and 21% had a clinically important fall (Z score change of -0.5 or more) against 0 in the control group. Serum parathyroid hormone and 25-hydroxyvitamin D fell, and urinary calcium rose. Mean annual weight gain was lower than on the comparison drug, with a similar trend for height [3].
- Population
- 63 children with epilepsy, as reported in the label [3].
- Sources
- [3]
- Caveats
- Too small and short to judge fracture risk [3].
Tested, and not shown to change it1
Bone
Limited evidence: alkaline potassium salts lowered a bone breakdown marker, with bone density unchanged in a review and up 1.7% in one trial. No fracture data.
CTX, P1NP, urinary calcium and parathyroid hormone did not differ from placebo.
The numbers and sources
- Effect
- Sources disagree. A meta-analysis of 14 studies found potassium bicarbonate and citrate lowered urinary calcium and the bone breakdown marker NTX, with no effect on bone density [11]. In one 2-year trial, 60 mEq of potassium citrate a day raised lumbar spine density 1.7% over placebo (95% CI 1.0 to 2.3) [12]. In 5 RCTs of postmenopausal women, potassium citrate lowered urinary NTX at 1 month (MD -4.05 nmol BCE/mmol creatinine, 95% CI -8.05 to -0.05). CTX, P1NP, urinary calcium and parathyroid hormone did not differ from placebo [13].
- Population
- 14 studies of alkaline potassium salts [11]; 201 healthy adults over 65 without osteoporosis, all given calcium and vitamin D [12]; 401 postmenopausal women [13].
- Sources
- [11], [12], [13]
- Caveats
- No fracture outcomes. Potassium chloride, the form in salt substitutes, lowered urinary calcium less than the alkaline salts [11].
How it compares with the reference method
Mixed results1
Week to week within a person
Small studies found PTH varied by 13% to 21% from week to week within a person, and one put the change needed between two results at 59.4%.
The numbers and sources
- Compared with
- The same person's weekly samples
- Effect
- In 20 adults sampled weekly for ten weeks, intact PTH had a within-person variation of 21.1%, a between-person variation of 24.9% and an assay variation of 3.8%, giving a reference change value of 59.4% [17]. In 91 adults in a European study that measured biointact PTH (PTH 1-84), within-person variation was 13.0% in men and 15.2% in women [16].
- Population
- 20 adults [17]. 91 adults aged 21 to 69 from five European countries [16].
- Sources
- [17], [16]
- Caveats
- Both studies enrolled people classed as healthy. The larger one measured biointact PTH, a different measurement from intact PTH [16].
Did not match the reference method2
Between assays
Not shown to match between assays: 15 immunoassays read from 45% lower to 123% higher than a reference intact PTH assay on the same samples.
The numbers and sources
- Compared with
- The Allegro intact PTH assay
- Effect
- In serum pools from dialysis patients measured with 15 commercial immunoassays, the median bias against the Allegro assay ran from -44.9% to 123.0%. When the Allegro result was 150 pg/mL the other assays read 83 to 323, and when it was 300 they read 160 to 638. The assays also differed in how much they picked up a PTH fragment [11]. A working group of the International Federation of Clinical Chemistry and Laboratory Medicine reports method-related variation of up to 5-fold, which it says makes it difficult to develop common reference intervals [2].
- Population
- 47 serum pools from dialysis patients [11].
- Sources
- [11], [2]
- Caveats
- The comparison used samples from dialysis patients. The authors propose assay-specific decision limits for people with kidney disease [11].
Other PTH assays, a different measurement
Small studies found two other PTH assays read lower than an intact PTH assay or the maker's limit, with upper limits of 28.9 to 34 pg/mL at higher vitamin D.
The numbers and sources
- Compared with
- The Allegro intact PTH assay, or the assay maker's own upper limit
- Effect
- In the same 280 adults aged 60 to 79, a second assay, the CAP assay, gave a 95% interval of 10 to 44 pg/mL where the intact PTH assay gave 13 to 64, and 9 to 34 against 10 to 46 in those with higher vitamin D [5]. In 183 vitamin D-replete adults measured with an automated third-generation assay the interval was 9.4 to 28.9 pg/mL, against a maker's upper limit of 38.4. Using 28.9 as the upper limit raised the share of patients with surgically proven primary hyperparathyroidism who had a high result from 66.6% to 90.1%, and changed how 18.6% of dialysis patients were classified [9].
- Population
- 280 adults aged 60 to 79 [5]. 898 adults, 81 patients with primary hyperparathyroidism and 264 dialysis patients [9].
- Sources
- [5], [9], [16]
- Caveats
- These are different assays from the intact PTH assay the ranges on this page are for, so their intervals are described here and have no band. A result reported as biointact PTH or PTH 1-84, the measure used in one study of week to week variation, is likewise a different measurement [16].
What studies tie it to
Linked in research3
Vitamin D status
Linked to higher PTH at lower vitamin D: 40% of people with 25-hydroxyvitamin D under 20 ng/mL had PTH above 65 pg/mL in 312,962 paired results.
The numbers and sources
- Effect
- In paired PTH and 25-hydroxyvitamin D results from one reference laboratory, 40% of people with 25-hydroxyvitamin D below 20 ng/mL and 51% of those below 10 ng/mL had PTH above 65 pg/mL. Median PTH fell smoothly as vitamin D rose, with no level above which it stopped falling, and the relation depended strongly on age [8]. In adults aged 60 to 79, the upper limit of PTH was 64 pg/mL in the whole group and 46 in those with 25-hydroxyvitamin D above 30 nmol/L [5]. With a third-generation assay, taking the reference group only from people with 25-hydroxyvitamin D of 30 ng/mL or above lowered the upper limit by 22.4% [9].
- Population
- 312,962 paired results measured from July 2010 to June 2011 [8]. 280 adults aged 60 to 79 [5]. 898 adults aged 18 to 89 with normal body mass index and kidney function, 183 of them vitamin D replete [9].
- Sources
- [8], [5], [9], [7], [6]
- Caveats
- Cross-sectional. The large series is of people whose doctors ordered both tests, not a reference population. Sources disagree on whether the reference range is to be lowered to account for vitamin D: two studies set upper limits near 46 pg/mL [5][7], and a third concluded the limit stays at 65 [6].
Kidney function
One study found PTH differed across tenths of kidney function in 1,814 patients, and 12% of those with an eGFR above 80 already had high PTH.
The numbers and sources
- Effect
- In outpatients tested across 153 centers, mean and median PTH differed significantly across deciles of estimated glomerular filtration rate (P below 0.001). High PTH, defined as above 65, was present in 12% of patients with an eGFR above 80 mL/min, while calcium and phosphorus stayed normal until eGFR fell below 40 [10]. Kidney guidelines set separate PTH targets for people on dialysis: the National Kidney Foundation's KDOQI guidelines used 150 to 300 pg/mL for stage 5 chronic kidney disease [11], and the KDIGO guideline uses two to nine times the upper limit of the assay [9]. The 2017 KDIGO update bases treatment on trends in results and not on a single abnormal value [12].
- Population
- 1,814 patients with a mean age of 71.1, 48% with diabetes [10].
- Sources
- [10], [11], [9], [12]
- Caveats
- Cross-sectional, in older patients, and the abstract misprints the unit of its PTH cut point. The dialysis targets are treatment targets for kidney failure and are not reference ranges. The KDIGO target is a multiple of each assay's upper limit, a different quantity from a result in pg/mL, so it has no band on this page.
Heart attack, stroke and cardiovascular death
Linked to more cardiovascular events at higher PTH: 45% more in people with the highest levels than in those with the lowest across 10 cohorts.
The numbers and sources
- Effect
- Comparing the highest with the lowest PTH concentrations, the pooled hazard ratio was 1.45 (95% CI 1.24 to 1.71) for all cardiovascular events, 1.50 (1.18 to 1.91) for fatal events and 1.48 (1.14 to 1.92) for non-fatal events [13].
- Population
- 12 prospective studies in the meta-analysis, 10 of them of total cardiovascular events, lasting 2 to 14 years, in mainly white populations with a mean age of 55 to 75 [13].
- Sources
- [13]
- Caveats
- Observational, with moderate differences between studies. The comparison is of each study's highest against its lowest PTH group, not of fixed levels. PTH also runs higher with low vitamin D and reduced kidney function (see the blocks above), so it may mark those and not cause events. In a trial that gave a drug for raised PTH, events did not fall significantly (see the next block).
Checked, no link found2
Death and cardiovascular events in a trial of cinacalcet in dialysis patients
One trial found cinacalcet, a drug for raised PTH, did not significantly reduce death or cardiovascular events in dialysis patients: 48.2% against 49.2% on placebo.
The numbers and sources
- Effect
- In patients on hemodialysis with moderate to severe secondary hyperparathyroidism, the composite of death, heart attack, hospitalization for unstable angina, heart failure or a peripheral vascular event occurred in 938 of 1,948 (48.2%) on cinacalcet and 952 of 1,935 (49.2%) on placebo, a relative hazard of 0.93 (95% CI 0.85 to 1.02, P = 0.11). Low blood calcium and gastrointestinal adverse events were significantly more frequent on cinacalcet [14].
- Population
- 3,883 patients with a median intact PTH of 693 pg/mL, followed for up to 64 months [14].
- Sources
- [14]
- Caveats
- A marker that tracks an outcome is not always one whose correction changes it. This is the unadjusted intention-to-treat result, and the trial was funded by the drug's maker. It studied people with kidney failure and very high PTH, so it says nothing about results near the reference range [14].
- Why limited
- This rests on one trial, of 3,883 people. Strength counts independent studies that agree, so one trial is limited at any size.
Death and illness in a trial of surgery for mild primary hyperparathyroidism
One trial found parathyroid surgery for mild primary hyperparathyroidism did not change deaths, fractures or cardiovascular events over 10 years compared with observation.
The numbers and sources
- Effect
- After 10 years, 8 patients had died in the surgery group and 7 in the observation group. Over the extended follow-up to 2018 there were 24 and 20 deaths. Cardiovascular events, strokes, cancer, peripheral fractures and kidney stones together numbered 52 in the surgery group and 49 in the observation group, and 7 patients in each group had vertebral fractures [15].
- Population
- 191 patients with mild primary hyperparathyroidism at eight Scandinavian centers, 95 assigned to surgery and 96 to observation [15].
- Sources
- [15]
- Caveats
- One trial of 191 people, 50 of whom withdrew. It studied mild disease with modest high calcium and no known complications, so it does not describe more severe disease [15].
Sources
- US Food and Drug Administration. 21 CFR 862.1545, Parathyroid hormone test system. Electronic Code of Federal Regulations. https://www.ecfr.gov/current/title-21/section-862.1545
- Sturgeon CM, Sprague S, Almond A, et al. Perspective and priorities for improvement of parathyroid hormone (PTH) measurement - A view from the IFCC Working Group for PTH. Clinica Chimica Acta. 2017. https://doi.org/10.1016/j.cca.2016.10.016
- US National Library of Medicine. Parathyroid hormone (PTH) blood test. MedlinePlus Medical Encyclopedia. Reviewed October 19, 2025. https://medlineplus.gov/ency/article/003690.htm
- Thorsteinsson D, Granath F, Bränström R, et al. Increasing incidence and prevalence of biochemically confirmed primary hyperparathyroidism in Stockholm, 2006-2020. The Journal of Clinical Endocrinology and Metabolism. 2026. https://doi.org/10.1210/clinem/dgag162
- Souberbielle JC, Cormier C, Kindermans C, et al. Vitamin D Status and Redefining Serum Parathyroid Hormone Reference Range in the Elderly. The Journal of Clinical Endocrinology and Metabolism. 2001. https://doi.org/10.1210/jcem.86.7.7689
- Aloia JF, Feuerman M, Yeh JK. Reference Range for Serum Parathyroid Hormone. Endocrine Practice. 2006. https://doi.org/10.4158/ep.12.2.137
- Touvier M, Deschasaux M, Montourcy M, et al. Interpretation of Plasma PTH Concentrations According to 25OHD Status, Gender, Age, Weight Status, and Calcium Intake: Importance of the Reference Values. The Journal of Clinical Endocrinology and Metabolism. 2014. https://doi.org/10.1210/jc.2013-3349
- Valcour A, Blocki F, Hawkins DM, Rao SD. Effects of Age and Serum 25-OH-Vitamin D on Serum Parathyroid Hormone Levels. The Journal of Clinical Endocrinology and Metabolism. 2012. https://doi.org/10.1210/jc.2012-2276
- Souberbielle JC, Massart C, Brailly-Tabard S, et al. Serum PTH reference values established by an automated third-generation assay in vitamin D-replete subjects with normal renal function: consequences of diagnosing primary hyperparathyroidism and the classification of dialysis patients. European Journal of Endocrinology. 2016. https://doi.org/10.1530/eje-15-0595
- Levin A, Bakris GL, Molitch M, et al. Prevalence of abnormal serum vitamin D, PTH, calcium, and phosphorus in patients with chronic kidney disease: Results of the study to evaluate early kidney disease. Kidney International. 2007. https://doi.org/10.1038/sj.ki.5002009
- Souberbielle JC, Boutten A, Carlier MC, et al. Inter-method variability in PTH measurement: Implication for the care of CKD patients. Kidney International. 2006. https://doi.org/10.1038/sj.ki.5001606
- Ketteler M, Block GA, Evenepoel P, et al. Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder: Synopsis of the Kidney Disease: Improving Global Outcomes 2017 Clinical Practice Guideline Update. Annals of Internal Medicine. 2018. https://doi.org/10.7326/m17-2640
- van Ballegooijen AJ, Reinders I, Visser M, Brouwer IA. Parathyroid hormone and cardiovascular disease events: A systematic review and meta-analysis of prospective studies. American Heart Journal. 2013. https://doi.org/10.1016/j.ahj.2013.02.014
- EVOLVE Trial Investigators, Chertow GM, Block GA, et al. Effect of Cinacalcet on Cardiovascular Disease in Patients Undergoing Dialysis. New England Journal of Medicine. 2012. https://doi.org/10.1056/nejmoa1205624
- Pretorius M, Lundstam K, Heck A, et al. Mortality and Morbidity in Mild Primary Hyperparathyroidism: Results From a 10-Year Prospective Randomized Controlled Trial of Parathyroidectomy Versus Observation. Annals of Internal Medicine. 2022. https://doi.org/10.7326/m21-4416
- Bottani M, Banfi G, Guerra E, et al. European Biological Variation Study (EuBIVAS): within- and between-subject biological variation estimates for serum biointact parathyroid hormone based on weekly samplings from 91 healthy participants. Annals of Translational Medicine. 2020. https://doi.org/10.21037/atm-19-4498
- Ercan M, Akbulut ED, Avcı E, et al. Determining biological variation of serum parathyroid hormone in healthy adults. Biochemia Medica. 2019. https://doi.org/10.11613/bm.2019.030702