Parathyroid Hormone (PTH)
Evaluation of bone mineral status will utilize an evaluation of vitamin D status based on two analytes: serum 25-hydroxyvitamin D and parathyroid hormone (PTH). Vitamin D is essential for active intestinal calcium absorption and plays a central role in maintaining calcium homeostasis and skeletal integrity. In addition, vitamin D has recently been linked to other non-skeletal conditions of public health significance, such as hypertension and cancer. Vitamin D is derived mainly from cutaneous synthesis in the presence of ultraviolet sunlight, whereas dietary intake constitutes a minor fraction. Serum 25(OH D) is the best indicator of vitamin D status. It is converted in the kidney, stimulated by PTH, to the hormonally active metabolite 1,25-dihydroxyvitamin D [1,25 (OH)2D]. Serum PTH concentration is a very sensitive indicator of calcium homeostasis and vitamin D deficiency. The inclusion of this measure to the NHANES laboratory protocol will increase the usefulness of the vitamin D measurement in evaluating vitamin D status, particularly as it relates to skeletal status. The inclusion of both of these markers in the NHANES survey will provide a more complete picture of vitamin D status.
Participants aged 6 years and older.
The Elecsys 1010 analyzer is a fully automatic run-oriented analyzer system for the determination of immunological tests using the ECL/Origen electrochemiluminescent process. All components and reagents for routine analysis are integrated in or on the analyzer. Parathyroid hormone is measured on the Elecsys 1010 using a sandwich principle.
Parathyroid hormone (PTH) is an 84 amino acid peptide produced by the parathyroid gland. Since the PTH molecule undergoes extensive proteolytic modifications, human serum contains both the intact molecule and several fragments. The biologically active N-terminal fragment has a half-life of only a few minutes. The secretory activity of the parathyroid gland can be determined by the selective measurement of the (mainly) intact parathyroid hormone. This Elecsys 1010 method is for the in vitro quantitative determination of intact parathyroid hormone in human serum and plasma. Together with vitamin D and calcitonin, PTH brings about the mobilization of calcium and phosphate from the skeletal system and increases the uptake of calcium in the intestine and the excretion of phosphate via the kidneys. Secretion of PTH is inhibited by high calcium concentrations and is promoted by low calcium concentrations. The ratios of intact hormone to peptide fragments may vary from individual to individual as well as between patients with hyperparathyroidism or chronic renal failure. The concentration of metabolically inactive PTH fragments increases in renal failure.
There were no changes to the equipment, lab method, or lab site from the previous 2 years.
A detailed description of the laboratory method used can be found on the NHANES website.
Blood specimens are processed, stored and shipped to University of Washington, Seattle, WA. Detailed specimen collection and processing instructions are discussed in the NHANES LPM. Read the LABDOC file for detailed data processing and editing protocols. The analytical methods are described in the Analytic methodology section.
There were no derived variables in this file.
Detailed instructions on specimen collection and processing can be found on the NHANES website.
The analysis of NHANES 2005–2006 laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES 2005–2006 Household Questionnaire Data Files contain demographic data, health indicators, and other related information collected during household interviews. They also contain sample weights for these age groups. The phlebotomy file includes auxiliary information such as the conditions precluding venipuncture. The household questionnaire and phlebotomy files may be linked to the laboratory data file using the unique survey participant identifier SEQN.
|Code or Value||Value Description||Count||Cumulative||Skip to Item|
|9 to 491||Range of Values||7331||7331|
|6.36||At or below detection limit fill value||15||7346|