ARUP's Laboratory Test Directory

N-Telopeptide, Cross-Linked, Urine : 0070062

Mnemonic: NTX

Methodology: Quantitative Chemiluminescent Immunoassay
Performed: Tue-Sat
Reported: 1-4 days
Specimen Required: Patient Prep: For monitoring therapy, a baseline specimen should be collected prior to initiation of therapy. Subsequent specimens for comparison should be collected at the same time of day as the baseline specimen.

Collect: Second-morning void or 24-hour urine. Refrigerate during collection. Collect without preservative.

Specimen Preparation: Transfer a 1 mL aliquot of urine from a well-mixed, second-morning void or 24-hour collection to an ARUP Standard Transport Tube. (Min: 0.5 mL)

Storage/Transport Temperature: Frozen.

Unacceptable Conditions: Specimens contaminated with blood or extensive hemolysis.

Stability (collection to initiation of testing): Ambient: 24 hours; Refrigerated: 1 week; Frozen: 2 years
Reference Interval:
 
Age Male Female
7-9 years 167-578 nM BCE/mM creatinine 201-626 nM BCE/mM creatinine
10-12 years 152-505 nM BCE/mM creatinine 173-728 nM BCE/mM creatinine
13-15 years 103-776 nM BCE/mM creatinine 38-515 nM BCE/mM creatinine
16-17 years 34-313 nM BCE/mM creatinine 20-144 nM BCE/mM creatinine
18 years and older 21-83 nM BCE/mM creatinine  
Premenopausal  17-94 nM BCE/mM creatinine
Postmenopausal  26-124 nM BCE/mM creatinine

Interpretive Data: NTx Units = nM BCE/mM creatinine

A decrease of 30-40% from the NTx baseline after three months of therapy is a typical response to anti-resorptive therapy.

NTx = Cross-linked N-telopeptide of Type I Collagen
BCE = Bone Collagen Equivalent
CPT Code(s): 82523
Cross References: Cross-Linked N-Telopeptide (N-Telopeptide, Cross-Linked, Urine), NTx (N-Telopeptide, Cross-Linked, Urine)