Bone-specific alkaline phosphatase

The laboratory also measured biochemical markers of bone metabolism. The urinary excretion of deoxypyrolidone, a marker of bone resorption, was elevated (128 nmol/mmol creatinine normal is 31-110 nmol/mmol creatinine). Bone-specific alkaline phosphatase, a marker of bone synthesis, was also elevated at 400 U/L (normal is 70-139 U/L for girls between 3 and 8 years of age) (Tsai et al., 1999). The concentration of another marker of bone resorption, NTx (N-teleopeptide), in the patient s serum was elevated (110 nmol BCE/L normal is 20-68 nmol BCE/L [bone collagen equivalents]). 

Markers of bone resorption can be measured in serum or urine, whereas bone formation markers, such as bone-specific alkaline phosphatase, are usually measured in serum. Measurement of bone markers allows for real-time assessment of bone resorption or formation and can be used to monitor therapy (Ravn et al., 2003). The pyridonolines (deoxypyridinoline and pyridinoline) and the N- and C-teleopep-tides are the most frequently measured markers of bone resorption. Pyridinoline and teleopep-tides (NTx and CTx) are increased in individuals with metabolic bone diseases associated... 

G9. Gomez, B., Ardakani, J. J., Jenkins, D., Cerelli, M. J., Daniloff, G. Y., and Kung, V. T., Monoclonal antibody assay for measuring bone specific alkaline phosphatase in serum. Clin. Chem. 41,1560-1566 (1995). 

Zinc-Dependent Enzymes. Despite the large number of zinc metaUoenzymes that have been identified, no single enzyme assay has yet found acceptance as an indicator of zinc status. This may be due to avid retention of zinc by these enzymes, even in the face of dietary zinc depletion, and to difficulties with reproducible measurements of activity. However, bone-specific alkaline phosphatase, extracellular SOD, lymphocytes, and plasma 5-nucleotidase appear to be responsive to zinc intake. ... 

Woitge HW, Seibel MJ, Ziegler R. Comparison of total and bone-specific alkaline phosphatase in patients with nonskeletal disorders or metabolic bone disease. Clin Chem 1996 42 1796-804. 

An estimated 75 million people are affected by osteoporosis to some degree in the United States, Europe, and Japan. Osteoporosis is a systematic skeletal disease characterized by bone mass and microarchitectural deterioration with a consequent increase in bone fragility and susceptibility to fracture. Operationally, osteoporosis can be defined as a certain level of bone mineral density. The definition of osteoporosis is somewhat arbitrary and is based on epidemiological data relating fracture incidence to bone mass. Uncertainty also is introduced due to variability in bone densitometry measurements. Other clinical measures to assess the skeleton include collagen cross-links (measure of bone resorption) and levels of bone-specific alkaline phosphatase and osteocalcin (bone formation). A list of biochemical markers of bone remodeling is provided in Table 37-3. Measurement of total serum alkaline phosphatase level and urinary hydroxyproline or calcium levels is of limited value. 

Bone-specific alkaline phosphatase Rich in osteoblasts... 

S.K. Hartwell, D. Somprayoon, P. Kongtawelert, S. Ongchai, O. Arppomchayanon, L. Ganranoo, et al., Online assay of bone specific alkaline phosphatase with a flow injection-bead injection system, Anal. Chim. Acta 600 (2007) 188. 

The AHRQ Report summarized numerous studies that evaluated the effects of soy products, including both protein and isoflavones, on various markers of bone health, such as bone mineral density (BMD) and biomarkers related to bone formation (bone-specific alkaline phosphatase and osteocalcin) and resorption (urinary hydroxyproline, urinary pyridinoline, and urinary deoxypyridinoline). In general, no effect of soy consumption on BMD or on biomarkers of bone formation resulted. Although a number of studies observed reductions in markers of bone resorption, these were restricted to only two biomarkers urinary pyridinoline and deoxypyridinoline. Moreover, the effects were not consistent across studies. The AHRQ report found no consistent evidence of dose-response effects for either soy isoflavones or soy protein on markers of bone turnover (Balk et al., 2005). 

Strontium ranelate is an orally active agent that can be classified as both an antiresorptive agent and a bone-forming agent (42,43). It is able not only to stimulate replication of preosteoblastic cells to promote bone formation but also is able to decrease osteoclastic activity to prevent bone resorption. Biochemical markers for bone formation (e g., bone-specific alkaline phosphatase), which normally decrease in the presence of antiresorptive therapy, are elevated in the presence of strontium ranelate (44). Lumbar spine BMD increased 11.4% in patients treated with this new agent. 

Musculoskeletal In ASSERT, a multicenter, open, 96-week study, 385 antiretroviral drug-naive adults with HIV infections were randomized to either abacavir -I- lamivudine or tenofovir-I-emtricitabine with efavirenz [60 ]. There was reduced bone mineral density in both groups, but to a greater extent with the latter (hip 1.9% versus 3.6% lumbar spine 1.6% versus 2.4%). Loss of at least 6% was more common in those who took tenofovir-I-emtricitabine (13% versus 3%). Markers of bone turnover (osteocalcin, procollagen 1, N-terminal propeptide, bone-specific alkaline phosphatase, and type 1 collagen cross-linked C telopep-tide) increased in both groups during the first 24 weeks and stabilized or improved thereafter, but without complete resolution. 

Other biochemical changes include depressed serum concentrations of calcium and inorganic phosphate, largely because of insufficient intestinal absorption directly relating to too Httle of these ions in the usual diet. Serum alkaline phosphatase, especially bone-specific alkaline phosphatase, is elevated because of osteoblastic cell overproduction when these cells attempt to form new bone tissue. 

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