Test Catalog

Test Id : NTXPR

NTX-Telopeptide, Urine

Useful For
Suggests clinical disorders or settings where the test may be helpful

As an adjunct in the diagnosis of medical conditions associated with increased bone turnover


Monitoring effectiveness of antiresorptive therapy in patients treated for osteopenia, osteoporosis, Paget disease, or other metabolic bone disorders

Profile Information
A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.

Test Id Reporting Name Available Separately Always Performed
NTXCT Creatinine, Random, U No Yes
NTXUR NTX-Telopeptide, U No Yes

Method Name
A short description of the method used to perform the test

NTXUR: Chemiluminescence Immunoassay

NTXCT: Enzymatic Colorimetric Assay

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

NTX-Telopeptide, U

Lists additional common names for a test, as an aid in searching

Crosslinked N-telopeptide of Type I Collagen (NTX), Urine

N-Telopeptide, Urine

NTX Creatinine


Collagen Crosslinks



Specimen Type
Describes the specimen type validated for testing


Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Patient Preparation: For 24 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.

Container/Tube: Plastic, 13-mL urine tube

Specimen Volume: 4 mL

Collection Instructions:

1. Collect second morning void.

2. No preservative.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Specimen with pH <5
Specimen containing preservatives

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Urine Frozen (preferred) 28 days
Refrigerated 14 days
Ambient 72 hours

Useful For
Suggests clinical disorders or settings where the test may be helpful

As an adjunct in the diagnosis of medical conditions associated with increased bone turnover


Monitoring effectiveness of antiresorptive therapy in patients treated for osteopenia, osteoporosis, Paget disease, or other metabolic bone disorders

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Human bone is continuously remodeled through a process of osteoclast-mediated bone formation and resorption. This process can be monitored by measuring serum and urine markers of bone formation and resorption. Approximately 90% of the organic matrix of bone is type I collagen, a helical protein that is cross-linked at the N- and C-terminal ends of the molecule. The amino acid sequences and orientation of the cross-linked alpha 2 N-telopeptide of type 1 collagen make it a specific marker of human bone resorption. N-terminal telopeptide (NTx) molecules are mobilized from bone by osteoclasts and subsequently excreted in the urine. Elevated levels of NTx indicate increased bone resorption.


Bone turnover markers are physiologically elevated during childhood, growth, and fracture healing. The elevations in bone resorption markers and bone formation markers are typically balanced in these circumstances and of no diagnostic value. By contrast, abnormalities in the process of bone remodeling can result in changes in skeletal mass and shape. Many diseases, in particular hyperthyroidism, all forms of hyperparathyroidism, most forms of osteomalacia and rickets (even if not associated with hyperparathyroidism), hypercalcemia of malignancy, Paget disease, multiple myeloma, and bony metastases, as well as various congenital diseases of bone formation and remodeling can result in accelerated and unbalanced bone turnover. Unbalanced bone turnover, usually without increase in bone formation, is also found in age-related and postmenopausal osteopenia and osteoporosis.


Disease-associated bone turnover abnormalities should normalize in response to effective therapeutic interventions, which can be monitored by measurement of serum and urine bone resorption and formation markers.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

All units are reported in nmol bone collagen equivalents (BCE)/mmol creatinine.



Tanner Stage I: 55-508 nmol BCE/mmol creatinine

Tanner Stage II: 21-423 nmol BCE/mmol creatinine

Tanner Stage III: 27-462 nmol BCE/mmol creatinine

Tanner Stage IV: <609 nmol BCE/mmol creatinine

Tanner Stage V: <240 nmol BCE/mmol creatinine



Tanner Stage I: 6-662 nmol BCE/mmol creatinine

Tanner Stage II: 193-514 nmol BCE/mmol creatinine

Tanner Stage III: 13-632 nmol BCE/mmol creatinine

Tanner Stage IV: <389 nmol BCE/mmol creatinine

Tanner Stage V: <132 nmol BCE/mmol creatinine


Adult (> or =18 years of age)


21-83 nmol BCE/mmol creatinine



Premenopausal: 17-94 nmol BCE/mmol creatinine

Postmenopausal: 26-124 nmol BCE/mmol creatinine

Provides information to assist in interpretation of the test results

Elevated levels of N-terminal telopeptide (NTx) indicate increased bone resorption.


Most patients with osteopenia or osteoporosis have low but unbalanced bone turnover with bone resorption dominating over bone formation. While this may result in mild elevations in bone turnover markers in these patients, finding significantly elevated urine NTx levels is atypical. Therefore, if levels are substantially elevated above the young adult reference range (>1.5- to 2-fold), the likelihood of coexisting osteomalacia or an alternative diagnosis, as described in the Clinical Information section, should be considered.


When alternative causes for elevated NTx have been excluded in a patient with osteopenia/osteoporosis, the patient must be considered at increased risk for accelerated progression of osteopenia/osteoporosis.


A 30% or greater reduction in this resorption marker 3 to 6 months after initiation of therapy indicates a probably adequate therapeutic response.


The Negotiated Rulemaking Committee of Health Care Finance Administration also recommends:

"Because of significant specimen to specimen collagen crosslink physiologic variability (15%-20%), current recommendations for appropriate utilization include: 1 or 2 baseline assays from specified urine collections on separate days; followed by a repeat assay about 3 months after starting antiresorptive therapy; followed by a repeat assay in 12 months; thereafter not more than annually, if medically necessary."

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Very dilute specimens may not allow measurement of a urine creatinine level; therefore, reporting of N-terminal telopeptide (NTx) values normalized to creatinine becomes impossible.


Inadvertent collection of urine for NTx measurements in a collection bottle containing an acidic preservative leads to substantial artifactual elevations of apparent NTx concentrations; such specimens are unacceptable and will be rejected.


Hemolysis and turbidity in samples may affect test results.


While the VITROS NTx test is used as an indicator of bone resorption, use of this test has not been established to predict development of osteoporosis or future fracture risk. A single NTx value cannot provide the rate of bone resorption as reported results do not contain a measure of time.


Use of this test has not been established in primary hyperparathyroidism or hyperthyroidism.


Biotin levels in urine remain elevated for up to 24 hours after oral or intravenous biotin administration.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Baxter I, Rogers A, Eastell R, Peel N: Evaluation of urinary N-telopeptide of type I collagen measurements in the management of osteoporosis in clinical practice. Osteoporos Int. 2013 Mar;24(3):941-947

2. Miller PD, Baran DT, Bilezikian JP, et al: Practical clinical application of biochemical markers of bone turnover: Consensus of an expert panel. J Clin Densitom. 1999;2(3):323-342

3. Delmas PD, Eastell R, Garnero P, Seibel MJ, Stepan J, Committee of Scientific Advisors of the International Osteoporosis Foundation: The use of biochemical markers of bone turnover in osteoporosis. Committee of Scientific Advisors of the International Osteoporosis Foundation. Osteoporos Int. 2000;11 Suppl 6:S2-S17

4. 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 Nov;63(5):369-374

Method Description
Describes how the test is performed and provides a method-specific reference

The Vitros N-terminal telopeptide (NTx) assay is a competitive immunoassay that depends on competition between NTx in the sample with a synthetic NTx peptide coated on the wells for binding by a horseradish peroxidase (HRP)-labeled antibody conjugate (mouse monoclonal anti-NTx). The conjugate is captured by the peptide coated on the wells, and unbound materials are removed by washing.


A reagent containing luminogenic substrates (a luminol derivative and a peracid salt) and an electron transfer agent (a substituted acetanilide) are added to the wells. The HRP in the bound conjugate catalyzes the oxidation of the luminol derivative, producing light. The electron transfer agent increases the level of light produced and prolongs the duration of light produced. The light signals are read by the system. The amount of HRP conjugate bound is inversely proportional to the concentration of NTx in the sample. Assay values are corrected for urinary dilution by urinary creatinine analysis and expressed in nanomoles bone collagen equivalents per liter (nM BCE/L) per millimole creatinine per liter (mM creatinine/L).(Instruction manual: Vitros Instructions for Use, N-Telopeptide GEM1426. Ortho-Clinical Diagnostics, Inc; Version 7.1, 09/06/2019)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday, Thursday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

Same day/1 to 5 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

14 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.



LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
NTXPR NTX-Telopeptide, U 44712-8
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
NTXCT Creatinine, Random, U 2161-8
NTX NTX 27939-8
NTXCR NTX-Telopeptide, U 44712-8

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports