N-telopeptide

A complete physical examination and laboratory analysis are needed to rule out secondary causes and to assess kyphosis and back pain. Laboratory testing may include complete blood count, liver function tests, creatinine, urea nitrogen, calcium, phosphorus, alkaline phosphatase, albumin, thyroid-stimulating hormone, free testosterone, 25-hydroxyvitamin D, and 24-hour urine concentrations of calcium and phosphorus. Urine or serum biomarkers (e.g., cross-linked N-telopeptides of type 1 collagen, osteocalcin) are sometimes used. 

Martini and Wood (2002) tested the bioavailability of 3 different sources of Ca in 12 healthy elderly subjects (9 women and 3 men of mean SEM age 70 3 and 76 6 years, respectively) in a 6-week crossover trial conducted in a Human Study Unit. Each Ca source supplied 1000 mg Ca/day and was ingested for 1 week with meals (as 500 mg Ca 2x/day), thus contributing to a high-Ca intake (1300 mg Ca/day). A low-Ca intake (300 mg Ca/day strictly from the basal diet) was adhered to for 1 week in-between each treatment. The Ca sources included skim milk, CCM-fortified OJ, and a dietary supplement of CaCOa. Assessment parameters were indirect measures predicted to reflect the relative bioavailability of Ca postprandially via an acute PTH suppression test (hourly for 4h). Longer-term responses to Ca supplementation were assessed via a number of urinary and serum hormone, mineral, and bone resorption biomarkers (i.e., vitamin D, Ca, phosphorus, and collagen t) e 1 N-telopeptide cross-links). 

Bone mass density (T-score, hip, spine), N-telopeptide serum calcium (adjusted forhypoalbuminemia), phosphorus, magnesium, renal function, liverfunction, serum electrolytes, signs and symptoms of toxicity (i.e., esophageal irritation)... 

Albumin-adjusted serum calcium N-telopeptide, alkaline phosphatase, phosphorus, osteocalcin, DEXA scan, bone and joint pain, fractures on x-ray (osteoporosis, Paget s disease)... 

McBride, D.J., Choe, V., Shapiro, J. R., and Brodsky, B. (1997). Altered collagen structure in mouse tail tendon lacking the alpha 2(1) chain./. Mol. Biol. 270, 275-284. Malone, J. P., George, A., and Veis, A. (2004). Type I collagen N-telopeptides adopt an ordered structure when docked to their helix receptor during fibrillogenesis. 

Scariano, J. K., Glew, R. H., Bou-Serhal, C. E., Clemens, J. D., Garry, P. J., and Baumgartner, R. N., Serum levels of cross-linked N-telopeptides and aminoterminal propeptides of type I collagen indicate low bone mineral density in elderly women. Bone 23, 471—477 (1998). 

Omote S, KidoT, Nishijo M, Nakagawa H, Suwazono E, Kobayashi E, Nogawa K. Urinarytype 1 collagen cross-linked N-telopeptIdes In Inhabitants 18 years after cessation of exposure to cadmium in Japan. Bull Environ Contam Toxicol 2006 76 187-194. 

Bone markers are used to assess bone turnover (resorption or formation) in patients with osteoporosis. This testing is useful for identifying osteoporotic individuals with elevated bone resorption and for predicting and assessing the response to therapy. Markers of bone resorption include collagen cross-finks (N telopeptide, deoxypyridinoline, or C-telopeptide). Because bone resorption and formation are coupled, markers of bone formation (BAP and serum osteo-... 

Laboratory and other findings include increased markers of bone turnover, and abnormal radiographs and bone scans. The most common finding leading to the diagnosis of Paget s disease is increased serum ALP (up to tenfold). Increases in markers of bone resorption (N-telopeptide, deoxypyridinohne, and C-telopeptide) reflect the osteoclas-... 

Figure 49-24 Pyridtnium cross-links and N-telopeptides of type I collagen. Cross-links occur at two intermolecular sites in the collagen fibril (i) two N-telopeptides are linked to a helical site at residue 930, and (2) two C-te opeptides are linked to helical residue 87.The location and amino acid sequence of the N-telopeptide (NTx) and the C-telopeptide (CTx) and the structures of the free pyridinium cross-links (pyridinoline and deoxypyridinoline) are shown.

Intermolecular cross-linking sites have been located that form the pyridinium cross-links in type I collagen (Figure 49-24). Two N-telopeptide sites are linked to the helical site at amino acid 930 (N-telopeptide) or two C-telopeptides are linked to the helical site amino acid 87 (C-telopeptide). 

In patients with PagePs disease treated with bisphospho-nates, N-telopeptide was suppressed more than total or free DPD or hydroxyproline and best predicted the outcome of therapy. ... 

Clemens JD, Herrick M, Singer F, Eyre DR. Evidence that serum NTx coUagen type 1 N-telopeptides) can act as an immunochemical markers of bone resorption. Clin Chem 1997 43 2058-63. 

EasteE R, MalMnak N, Weiss S, Ettinger M, Pettinger M, Cain D, et al. Biological variability of serum and urinary N-telopeptide of type I collagen in postmenopausal women. J Bone Miner Res 2000 15 594-8. 

Gertz BJ, Clemens JD, Holland SD, Yuan W> Greenspan S. Application of a new serum assay for type I collagen cross-hnked N-telopeptides assessment of clinical changes in bone turnover with and... 

Hanson DA, Weis MAE, Bollen A-M, Maslan SL, Singer FR, Eyre DR. A specific immunoassay for monitoring human bone resorption quantitation of type I collagen cross-linked N-telopeptides in urine. 

Rosen RH, Dresner-PoUak R> Moses AC, Rosenblatt M, Zeind AJ, Clemens JD, et al. Specificity of urinary excretion of crossLinked N-telopeptide of type I collagen as a marker of bone turnover. Calcif Tissue Int 1994 54 26-9. 

D. L. Schneider and E. L. Barrett-Connor Urinary N-telopeptide levels discriminate normal osteopenic, and osteoporotic bone mineral density. Archives of Internal Medicine 157, 1241 (1997). 

Alkaline phosphatase Arthrocentesis with synovial fluid analysis Arthrography Arthroscopy Bone densitometry Bone scan Bone x-ray Electromyography HLA-B27 antigen Lactate dehydrogenase Magnetic resonance imaging Myoglobin N-telopeptide Rheumatoid factor Spinal x-rays Uric acid... 

Mononucleosis spot test Myoglobin Neutrophils N-telopeptide 5 -Nucleotidase Osmolality Parathyroid hormone Partial thromboplastin time, activated... 

Another case of priapism in a 45-year-old male on risperidone and sodium valproate is reported [267 ]. Musculoskeletal A study of risperidone-associated prolactin elevation and markers of bone turnover found that prolactin levels significantly increased and N-telopeptide cross-links (markers of bone resorption) significantly decreased [268 ]. No differences were noted between men and women osteocalcin, N-telopeptide cross-links osteocalcin ratios, oes-tradiol and testosterone did not significantly change and there were no significant associations between risperidone dose and prolactin levels. 

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