N-Telopeptide Cross-Links (NTx), Urine
| N-Telopeptide Cross-Links (NTx), Urine | | | |
| Number | | 141093 |
| CPT | | 82523; 82570 |
| Related Information | | N-Telopeptide Cross-Links (NTx), Serum |
| Synonyms | | Collagen Cross-Linked N-Telopeptide ; N-Telopeptide ; NTx Test ; Osteomark® |
| Special Instructions | | Values obtained with different assay methods should not be used interchangeably in serial testing. It is recommended that only one assay method be used consistently to monitor each patient's course of therapy. This procedure does not provide serial monitoring; it is intended for one-time use only. If serial monitoring is required, please use the serial monitoring number 511097 (see test below) to order. |
| Specimen | | Urine |
| Volume | | 20 mL |
| Minimum Volume | | 1 mL |
| Container | | Transport tube, no preservative |
| Collection | | Collect a second void of the morning or an aliquot of a 24-hour urine (no preservative). When monitoring therapy, baseline samples should be collected prior to initiation of therapy. Subsequent specimens should be collected at the same time of day as baseline specimens. |
| Storage Instructions | | Refrigerate |
| Causes for Rejection | | Quantity not sufficient for analysis; whole blood contamination; hemolysis |
| Reference Interval | | - Pediatrics: see table.1
- Adults: male: 3-51 mM BCE/mmol creatinine, female: 5-65 mM BCE/mmol creatinine
| Tanner Stage | Male
(mM BCE/mmol creatinine) | Female
(mM BCE/mmol creatinine) | | I | 55-508 | 6-662 | | II | 21-423 | 193-514 | | III | 27-462 | 13-632 | | IV | <609 | <389 | | V | <240 | <132 |
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| Use | | Evaluation of osteoporosis and assessment of antiresorptive therapy |
| Methodology | | Enzyme immunoassay (EIA) |
| Additional Information | | Approximately 90% of the organic matrix of mammalian bone consists of type I collagen that is cross-linked at the N-terminal and C-terminal ends.2 This highly cross-linked structure provides for the basic fabric and tensile strength of bone tissue. The collagen infrastructure of bone undergoes a continuous process of remodeling that involves osteoclast-mediated bone resorption and osteoblast-mediated bone formation. Bone resorption by osteoclasts results in the production of cross-linked N-telopeptides of type I collagen (NTx). NTx is specific to bone and is found in urine as a stable end product of bone degradation. The NTx test measures the concentration of cross-linked N-telopeptides of type I collagen.2 Levels of NTx correlate with the rate of bone resorption. Bone resorption rates exceeding bone formation results in a net loss of bone and ultimately osteopenia or osteoporosis.3,4 Osteoporotic fractures are a major source of morbidity and mortality in older women.5 The NTx test is intended for use in predicting skeletal response to hormonal antiresorptive therapy in postmenopausal women. The NTx test can also be used to monitor the efficacy of antiresorptive therapy6 in postmenopausal women, women with osteoporosis, and individuals with Paget disease. The NTx test can also be used in monitoring the effect of estrogen-suppressing therapies on the rate of bone resorption. A recent study7 supported the use of NTx to identify the probability for a decrease in bone mineral density after 1 year in postmenopausal women receiving calcium supplement relative to those treated with hormonal antiresorptive therapy. |
| Footnotes | | - Mora S, Prinster C, Proverbio MC, et al, “Urinary Markers of Bone Turnover in Healthy Children and Adolescents: Age-Related Changes and Effect of Puberty,” Calcif Tissue Int, 1998, 63(5):369-74.
- Endres DB and Rude RK, “Mineral and Bone Metabolism,” Tietz Textbook of Clinical Chemistry, 3rd ed, Burtis CA and Ashwood ER, eds, Philadelphia, PA: WB Saunders Co, 1999, 1349-457.
- Garnero P, Shi WJ, Gineyts E, et al, “Comparison of New Biochemical Markers of Bone Turnover in Late Postmenopausal Osteoporotic Women in Response to Alendronate Treatment,” J Clin Endocrinol Metab, 1994, 79(6):1693-700.
- Garnero P, Sornay-Rendu E, Chapuy MC, et al, “Increased Bone Turnover in Late Postmenopausal Women Is a Major Determinant of Osteoporosis,” J Bone Miner Res, 1996, 11(3):337-49.
- Prestwood KM, Pilbeam CC, Burleson JA, et al, “The Short-Term Effects of Conjugated Estrogen on Bone Turnover in Older Women,” J Clin Endocrinol Metab, 1994, 79(2):366-71.
- Liberman UA, Weiss SR, Broll J, et al, “Effect of Oral Alendronate on Bone Mineral Density and the Incidence of Fractures in Postmenopausal Osteoporosis. The Alendronate Phase III Osteoporosis Treatment Study Group,” N Engl J Med, 1995, 333(22):1437-43.
- Chesnut CH III, Bell NH, Clark GS, et al, “Hormone Replacement Therapy in Postmenopausal Women: Urinary N-telopeptide of Type I Collagen Monitors Therapeutic Effect and Predicts Response of Bone Mineral Density,” Am J Med, 1997, 102(1):29-37
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| References | | Delmas PD, “Biochemical Markers for the Assessment of Bone Turnover,” Osteoporosis: Etiology, Diagnosis, and Management, 2nd ed, Riggs BL and Melton LJ III, eds, Philadelphia, PA: Lippincott-Raven, 1995, 319-33. National Osteoporosis Foundation, Fast Facts on Osteoporosis, Washington, DC: National Osteoporosis Foundation, 1994. National Osteoporosis Foundation, The Older Person's Guide to Osteoporosis, Washington, DC: National Osteoporosis Foundation, 1993. Robins SP, Woitge H, Hesley R, et al, “Direct, Enzyme-Linked Immunoassay for Urinary Deoxypyridinoline As a Specific Marker for Measuring Bone Resorption,” J Bone Mineral Res, 1994, 9(10)1643-9. Rosen HN, Dresner-Pollak R, Moses AC, et al, “Specificity of Urinary Excretion of Cross-Linked N-Telopeptides of Type I Collagen As a Marker of Bone Turnover,” Calcif Tissue Int, 1994, 54(1):26-9. Slovick DM, “A Special Report: Osteoporosis,” Harvard Health Letter, Boston, MA: Harvard Medical School, Health Publications Group, 1993. |
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