Reference Range for Serum Parathyroid Hormone

doi:10.4158/EP.12.2.137

Endocrine Practice

Volume 12, Issue 2, March–April 2006, Pages 137-144

https://doi.org/10.4158/EP.12.2.137 Get rights and content

ABSTRACT

Objective

To determine whether the reference range for parathyroid hormone (PTH) should be lowered (from 65 pg/mL to a proposed value of 46 pg/mL) with use of the Allegro radioimmunometric assay.

Methods

We examined the reference range for PTH, adjusted for serum 25-hydroxyvitamin D (25-OHD), in 503 healthy African American and white women, who were 20 to 80 years old. We also analyzed other factors that are thought to influence PTH levels.

Results

Univariate predictors of PTH were identified, and a multivariate model was developed with use of the variables and PTH. Serum PTH was significantly higher in black study subjects than in white study subjects (P < 0.02). Increasing PTH was also significantly correlated with increasing body mass index, age, and serum creatinine and with decreasing dietary calcium intake and serum 25-OHD levels. A stepwise multiple linear regression analysis yielded the following predictors of PTH: body mass index (R² = 9.4%), age (R² = 1.0%), and serum 25-OHD (R² = 0.8%). In our study population, many PTH values were above the proposed new upper limit of 46 pg/mL.

Conclusion

The upper limit of the reference range for serum PTH should not be changed. Factors to be considered in analysis of serum PTH values in the upper reference range in patients with normocalcemia include obesity, race, 25-OHD levels, advanced age, serum creatinine, and dietary calcium intake. (Endocr Pract. 2006; 12:137-144)

Section snippets

INTRODUCTION AND BACKGROUND

The earliest radioimmunoassay for parathyroid hormone (PTH) used polyclonal antisera directed against intact PTH(1-84) (1). Most early assays were directed against the middle or C-terminus of the PTH peptide (2). Investigators soon found that several fragments of PTH in serum were derived from the parathyroid glands and from peripheral metabolism of PTH(1-84) (3., 4., 5., 6., 7., 8., 9., 10., 11.). The later development of a 2-site radioimmunometric assay allowed measurement of primarily intact

Study Participants

Participants were recruited from advertising in the local media and through a direct mail campaign. Exclusion characteristics consisted of any chronic illness, including hypertension, diabetes, or morbid obesity, any past history of illness or use of medication known to affect bone metabolism, any use of oral contraceptives or hormone replacement therapy, or a history of hysterectomy. After telephone screening, women were further excluded from the study because of abnormal results of blood

Predictors of PTH—Univariate and Multivariate Analysis

In Table 1, we provide descriptive statistics of all continuous variables and the univariate correlations with PTH. Mean PTH was significantly higher in black study subjects (38.9 ± 14.0 pg/mL) than in white study subjects (35.8 ± 12.6 pg/mL) (P < 0.02). Increasing PTH was also significantly correlated with increasing BMI (Fig. 1), increasing age (Fig. 2), decreasing dietary calcium, increasing serum creatinine, and decreasing 25-OHD (Fig. 3). The largest correlation was between PTH and BMI (r =

DISCUSSION

The current study confirms the manufacturer’s reference range for serum PTH with use of the Allegro radioimmunometric assay and establishes that its upper limit should not be lowered from 65 pg/mL. Our study participants were healthy volunteers recruited through a direct mail campaign. Volunteers with chronic illness, morbid obesity, hypertension, diabetes, thyroid disease, or osteoporosis were excluded from the study. They were further found to be healthy by a thorough history and physical

CONCLUSION

The data in this healthy female population suggest that the upper limit of the reference range for PTH with use of the intact Allegro radioimmunometric assay should not be lowered. Instead, in patients with normal serum calcium levels and PTH in the upper reference range, clinicians should consider whether they have higher PTH values because of increased body weight, advanced age, reduced renal function, low dietary calcium intake, or low serum 25-OHD levels. When these variables are not

ACKNOWLEDGMENT

This research was funded by the National Institute of Aging (RO1 AG15325), National Institutes of Health. We thank Sharon Sprintz, RT, and Jane Moore, RN, for their expertise and Audrey Gallo-Neglia for preparation of the manuscript.

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This is consistent with the results of Christopher [18]. PTH concentrations have also been reported to increase with age, independent of those possible confounding factors, such as vitamin D deficiency and renal impairment [35–37]. The non-compliance of people over 70 years old may be related to the sample size.
Parathyroid hormone (PTH) and vitamin D plays a major role in calcium (Ca) homeostasis and bone turnover. The purpose of this study was to assess which factors (sex, age, time of blood sampling, season of the year, temperature and sunshine hours (SHH)) had the greatest impact on plasma PTH, 25-OH-VitD, and Ca levels, and then whether these effects were clinically acceptable in a large number of Southwestern Chinese subjects.
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The concentrations of serum PTH in females were significantly higher than those in males, while the 25-OH-VitD and Ca were opposite. The concentration of PTH in data collection decreased in summer and increased in spring. The concentration of 25-OH-VitD decreases in spring and increases in autumn. PTH concentrations were negatively correlated with last month temperature and SHH, while 25-OH-VitD were opposite. Linear regression showed that season may be the main factor affecting serum PTH and 25-OH-VitD levels, and these effects were not clinically acceptable.
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Original ArticleReference Range for Serum Parathyroid Hormone

ABSTRACT

Objective

Methods

Results

Conclusion

Section snippets

INTRODUCTION AND BACKGROUND

Study Participants

Predictors of PTH—Univariate and Multivariate Analysis

DISCUSSION

CONCLUSION

ACKNOWLEDGMENT

Metabolism.

Kidney Int.

Mayo Clin Proc.

Semin Nephrol.

Am J Med.

Metabolism.

Am J Clin Nutr.

Immunoassay of bovine and human parathyroid hormone

Proc Natl Acad Sci U S A.

Clinical utility of radioimmunoassays for parathyroid hormone

Miner Electrolyte Metab.

Direct release of parathyroid hormone fragments from functioning bovine parathyroid glands in vitro

J Clin Invest.

Effects of plasma calcium concentration on the relative proportion of hormone and carboxyl fragments in parathyroid venous blood

Endocrinology.

The secretion of parathormone fragments 34-84 and 37-84 by dispersed porcine parathyroid cells

Endocrinology.

The content of carboxyl-terminal fragments of parathormone in extracts of fresh bovine parathyroids

Endocrinology.

Metabolism of radioiodinated bovine parathyroid hormone in the rat

Endocrinology.

Metabolism of parathyroid hormone by Kupffer cells: analysis by reverse-phase high-performance liquid chromatography

Biochemistry.

The peripheral metabolism of parathyroid hormone

N Engl J Med.

Highly sensitive two-site immunoradiometric assay of parathyrin, and its clinical utility in evaluating patients with hypercalcemia

Clin Chem.

Circulating intact parathyroid hormone measured by a two-site immunochemiluminometric assay

J Clin Endocrinol Metab.

Evaluation of a new, rapid and automated immunochemiluminometric assay for the measurement of serum intact parathyroid hormone

Ann Clin Biochem.

Clinical and laboratory evaluation of a two-site immunoradiometric assay for intact parathyroid hormone

Ann Clin Biochem.

Performance and diagnostic application of a two-site immunoradiometric assay for parathyrin in serum

Clin Chem.

Immunochemiluminometric and immunoradiometric determinations of intact and total immunoreactive parathyrin: performance in the differential diagnosis of hypercalcemia and hypoparathyroidism

Clin Chem.

Two-site assay of intact parathyroid hormone in the investigation of primary hyperparathyroidism and other disorders of calcium metabolism compared with a midregion assay

J Clin Endocrinol Metab.

Original Article
Reference Range for Serum Parathyroid Hormone