Collagen Cross-Linked N-Telopeptide

Collagen Cross-Linked N-Telopeptide

Synonym/acronym: NTx.

Common use

To evaluate the effectiveness of treatment for osteoporosis.


Urine (2 mL) from a random specimen collected in a clean plastic container.

Normal findings

(Method: Immunoassay)
Adult male 18–29 yrLess than 100 mmol bone collagen equivalents (BCE)/mmol creatinine
Adult male 30–59 yrLess than 65 mmol BCE/mmol creatinine
Adult female (premenopausal)Less than 65 mmol BCE/mmol creatinine
Tanner StageMaleFemale
I55–508 (mmol BCE/mmol creatinine)6–662 (mmol BCE/mmol creatinine)
II21–423 (mmol BCE/mmol creatinine)193–514 (mmol BCE/mmol creatinine)
III27–462 (mmol BCE/mmol creatinine)13–632 (mmol BCE/mmol creatinine)
IVLess than 609 (mmol BCE/mmol creatinine)Less than 389 (mmol BCE/mmol creatinine)
VLess than 240 (mmol BCE/mmol creatinine)Less than 132 (mmol BCE/mmol creatinine)
Values are higher in children.


Osteoporosis is the most common bone disease in the West. It is often called the “silent disease” because bone loss occurs without symptoms. The formation and maintenance of bone mass is dependent on a combination of factors that include genetics, nutrition, exercise, and hormone function. Normally, the rate of bone formation is equal to the rate of bone resorption. After midlife, the rate of bone loss begins to increase. Osteoporosis is more commonly identified in women than in men. Other risk factors include thin, small-framed body structure; family history of osteoporosis; diet low in calcium; white or Asian race; excessive use of alcohol; cigarette smoking; sedentary lifestyle; long-term use of corticosteroids, thyroid replacement medications, or antiepileptics; history of bulimia, anorexia nervosa, chronic liver disease, or malabsorption disorders; and postmenopausal state. Osteoporosis is a major consequence of menopause in women owing to the decline of estrogen production. Osteoporosis is rare in premenopausal women. Estrogen replacement therapy (after menopause) is one strategy that has been commonly employed to prevent osteoporosis, although its exact protective mechanism is unknown. Results of some recently published studies indicate that there may be significant adverse side effects to estrogen replacement therapy; more research is needed to understand the long-term effects (positive and negative) of this therapy. Other treatments include raloxifene (selectively modulates estrogen receptors), calcitonin (interacts directly with osteoclasts), and bisphosphates (inhibit osteoclast-mediated bone resorption).

A noninvasive test to detect the presence of collagen cross-linked N-telopeptide (NTx) is used to follow the progress of patients who have begun treatment for osteoporosis. NTx is formed when collagenase acts on bone. Small NTx fragments are excreted in the urine after bone resorption. A desirable response, 2 to 3 mo after therapy is initiated, is a 30% reduction in NTx and a reduction of 50% below baseline by 12 mo.

This procedure is contraindicated for



  • Assist in the evaluation of osteoporosis
  • Assist in the management and treatment of osteoporosis
  • Monitor effects of estrogen replacement therapy

Potential diagnosis

Increased in

  • Conditions that reflect increased bone resorption are associated with increased levels of N-telopeptide in the urine

  • Alcoholism (related to inadequate nutrition)
  • Chronic immobilization
  • Chronic treatment with anticonvulsants, corticosteroids, gonadotropin releasing hormone agonists, heparin, or thyroid hormone
  • Conditions that include hypercortisolism, hyperparathyroidism, hyperthyroidism, and hypogonadism
  • Gastrointestinal disease (related to inadequate dietary intake or absorption of minerals required for bone formation and maintenance)
  • Growth disorders (acromegaly, growth hormone deficiency, osteogenesis imperfecta)
  • Hyperparathyroidism (related to imbalance in calcium and phosphorus that affects the rate of bone resorption)
  • Multiple myeloma and metastatic tumors
  • Osteomalacia (related to defective bone mineralization)
  • Osteoporosis
  • Paget’s disease
  • Postmenopausal women (related to estrogen deficiency)
  • Recent fracture
  • Renal insufficiency (related to excessive loss through renal dysfunction)
  • Rheumatoid arthritis and other connective tissue diseases (related to inadequate diet due to loss of appetite)

Decreased in

    Effective therapy for osteoporosis

Critical findings


Interfering factors

  • NTx levels are affected by urinary excretion, and values may be influenced by the presence of renal impairment or disease.

Nursing Implications and Procedure

Potential nursing problems

ProblemSigns & SymptomsInterventions
Health maintenance (Related to failure to regulate diet; lack of exercise; alcohol use; smoking)Inability or failure to recognize or process information toward improving health and preventing illness with associated mental and physical effectsEncourage regular participation in weight-bearing exercise; assess diet, smoking, and alcohol use; teach the importance of adequate calcium intake with diet and supplements; refer to smoking cessation and alcohol treatment programs; collaborate with physician for bone density evaluation
Socialization (Related to altered body image and associated change in physical appearance)Expresses concern about changes in appearance related to kyphosis or lordosis; isolates self at home and refuses to participate in usual social or familial activities; expresses discomfort with social situations; fear of fallingEncourage continuation of activates inclusive of those with whom there is an established friend or family relationship; encourage participation in a community support group; encourage realistic view of physical appearance; acknowledge patient’s perception of changed image and the impact on his or her life
Self-care (Related to loss of bone mass and physical deformity; pain; and limited range of motion)Difficulty fastening clothing; difficulty performing personal hygiene; inability to maintain appropriate appearance; difficulty with independent mobilityReinforce self-care techniques as taught by occupational therapy; ensure the patient has adequate time to perform self-care; encourage use of assistive devices to maintain independence; ask if there is any interference with lifestyle activities
Fall risk (Related to altered mobility associated with loss of bone mass)Postural instability; jerky movement; uncoordinated movement; slow, unsteady movementTeach about fall precautions; assess home environment for fall risk; evaluate medications for contributory cause related to recent falls; encourage physical therapy to facilitate moderate exercise; teach that low, comfortable walking shoes can promote safe ambulation and decrease fall risk


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in diagnosing osteoporosis and evaluating the effectiveness of therapy.
  • Obtain a history of the patient’s complaints, including a list of known allergens.
  • Obtain a history of the patient’s musculoskeletal system and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there should be no discomfort during the procedure.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.


  • Potential complications: N/A
  • Instruct the patient to cooperate fully and to follow directions.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection.
  • Instruct the patient to collect a second-void morning specimen as follows: (1) void and then drink a glass of water; (2) wait 30 min, and then try to void again.
  • Promptly transport the specimen to the laboratory for processing and analysis.


  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Nutritional Considerations: Increased NTx levels may be associated with osteoporosis. Nutritional therapy may be indicated for patients identified as being at high risk for developing osteoporosis. Educate the patient about the National Osteoporosis Foundation’s guidelines regarding a regular regimen of weight-bearing exercises, limited alcohol intake, avoidance of tobacco products, and adequate dietary intake of vitamin D and calcium. Dietary calcium can be obtained in animal or plant sources. Milk and milk products, sardines, clams, oysters, salmon, rhubarb, spinach, beet greens, broccoli, kale, tofu, legumes, and fortified orange juice are high in calcium. Milk and milk products also contain vitamin D and lactose to assist in absorption. Cooked vegetables yield more absorbable calcium than raw vegetables. Patients should also be informed of the substances that can inhibit calcium absorption by irreversibly binding to some of the calcium and making it unavailable for absorption, such as oxalates, which naturally occur in some vegetables (e.g., beet greens, collards, leeks, okra, parsley, quinoa, spinach, Swiss chard) and are found in tea; phytic acid, found in some cereals (e.g., wheat bran, wheat germ); phosphoric acid, found in dark cola; and excessive intake of insoluble dietary fiber (in excessive amounts). Excessive protein intake also can affect calcium absorption negatively, especially if it is combined with foods high in phosphorus. Vitamin D is synthesized by the skin and is available in fortified dairy foods and cod liver oil.
  • Recognize anxiety related to test results, and be supportive of impaired activity related to lack of muscular control, perceived loss of independence, and fear of shortened life expectancy.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
  • Patient Education

    • Instruct the patient to resume usual diet, fluids, medications, and activity, as directed by the HCP.
    • Discuss the implications of abnormal test results on the patient’s lifestyle.
    • Provide teaching and information regarding the clinical implications of the test results, as appropriate.
    • Educate the patient regarding access to counseling services. Provide contact information, if desired, for the American College of Rheumatology (, the Institute of Medicine of the National Academies (, or the National Osteoporosis Foundation (
    • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
    • Answer any questions or address any concerns voiced by the patient or family.
    • Discuss with the patient the effect of alcohol consumption on nutritional status and calcium intake.
  • Expected Patient Outcomes

    • Knowledge
    • Identifies the importance of adhering to the recommended therapeutic regime to maintain health
    • Describes the importance of early intervention on preserving bone density and reducing future risk of falls and fractures
    • Skills
    • Proficiently demonstrates the proper use of assistive devices to support mobility and increase activity
    • Independently demonstrates weight-bearing exercises designed to promote bone growth
    • Attitude
    • Discusses perceived change in physical appearance with a positive attitude
    • Selects positive changes in lifestyle that can preserve bone health

Related Monographs

  • Related tests include ALP, BMD, calcitonin, calcium, creatinine, creatinine clearance, osteocalcin, PTH, phosphorus, radiography bone, and vitamin D.
  • Refer to the Musculoskeletal System table at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners
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References in periodicals archive ?
Urinary excretion of type I collagen cross-linked N-telopeptide in children: biological variability and reference limits.
A specific immunoassay for monitoring human bone resorption: quantification of type 1 collagen cross-linked N-telopeptides in urine.
A specific immunoassay for monitoring human bone resorption: quantitation of type I collagen cross-linked N-telopeptides in urine.
Thus far, urinary pyridinoline and deoxypyridinoline, serum osteocalcin, bone specific alkaline phosphatase, serum type I collagen cross-linked N-telopeptides (NTx), the C-terminal pyridinoline cross-linked telopeptide of type I collagen, and urinary excretion of NTx were reported to undergo circadian periodicities with high values at night (1-5).