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  • 1
    Electronic Resource
    Electronic Resource
    Regulation of calcium absorption by 1,25,dihydroxy-vitamin D—Studies of the effects of a bisphosphonate treatment (1982)
    Springer
    Calcified tissue international 34 (1982), S. 317-320 
    Details
    ISSN: 1432-0827
    Keywords: 1,25-Dihydroxy-vitamin D ; Calcium absorption ; Parathyroid hormone ; Bisphosphonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In 10 patients with Paget's disease of bone and 2 patients with osteoporosis, we studied the effects of hypocalcemia and hypophosphatemia induced by disodium-(3-amino-1-hydroxypropylidene)-1,-bisphosphonate (APD) treatment on the serum concentration of PTH and 1,25-dihydroxyvitamin D [1,25(OH)2D3] and on calcium absorption and balance. The fall in serum calcium and phosphate was associated with a rise in the serum concentration of PTH and 1,25(OH)2D3, coupled with increases in net calcium absorption and calcium balance. The concentration of 1,25(OH)2D3 was significantly related (P〈0.001) to the serum calcium (r=0.66), the serum phosphate (r=0.78), and the serum PTH (r=0.71), confirming the interrelated control of these parameters on 1,25(OH)2D3 production. Moreover, the rise in 1,25(OH)2D3 caused an appropriate rise in calcium absorption (r=0.74) and calcium balance (r=0.86), showing that this vitamin D metabolite contributes as a hormone to calcium homeostasis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411260
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  • 2
    Electronic Resource
    Electronic Resource
    Precision of dual photon absorptiometry measurements: comparison of three different methods of selection of the region of interest (1989)
    Springer
    European journal of nuclear medicine 15 (1989), S. 183-188 
    Details
    ISSN: 1619-7089
    Keywords: Bones ; Mineral ; Dual photon absorptiometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To determine the short-term reproducibility of bone mass calculations with dual photon absorptiometry of the lumbar spine (L2–L4), duplicate measurements in healthy subjects were used. Three different methods for selection of region of interest were compared: a rectangular region with variable height and width, an irregular region to be drawn freely by the operator and the standard calculation software supplied with the bone densitometer. Contributions of changes in size and location of the region of interest on calculated bone mineral mass were also investigated. An increase in height of the region by 2 scan lines caused an increase in bone mineral content (BMC) of 8.4%±1.8%. Enlargement in width by 2 pixels in each scan line caused an increase in BMC of 2.5%±1.3%. The difference between these region of interest changes was significant (P0.0005). The use of a rectangular region, optimized to enclose L2–L4 in each person but of the same size in both measurements, resulted in a reproducibility of 1.4% and 0.7% respectively for 2 observers, with an inter observer variation of 1.2%. The reproducibility of the duplicate measurements was worse for the other methods of region of interest selection. A further series of duplicate DPA measurements in normal subjects, but with a standard meal between the measurements, showed a larger variation in the results. Again the reproducibility of the calculations using the rectangular region was better than with the other methods, with much less inter observer variation. These data suggest that calculation of dual photon absorptiometry results with a constant region of interest is preferred for the detection of small changes in lumbar bone mass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00253791
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The reproducibility of single photon absorptiometry in a clinical setting (1989)
    Springer
    European journal of nuclear medicine 15 (1989), S. 269-273 
    Details
    ISSN: 1619-7089
    Keywords: Bones ; Mineral ; Single photon absorptionmetry ; Dual photon absorptiometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The reproducibility of single photon absorptiometry (SPA) results for detection of changes in bone mineral content (BMC) was evaluated in a clinical setting. During a period of 18 months with 4 different sources, the calibration scans of an aluminium standard had a variation of less than 1% unless the activity of the 125I source was low. The calibration procedure was performed weekly and this was sufficient to correct for drift of the system. The short term reproducibility in patients was assessed with 119 duplicate measurements made in direct succession. The best reproducibility (CV=1.35%) was found for fat corrected BMC results expressed in g/cm, obtained at the site proximal to the 8 mm space between the radius and ulna. Analysis of all SPA scans made during 1 year (487 scans) showed a failure of the automatic procedure to detect the space of 8 mm between the forearm bones in 19 scans (3.9%). A space adjacent to the ulnar styloid was taken as the site for the first scan in these examinations. This problem may be recognized and corrected relatively easy. A significant correlation was found between BMC of the lower arm and BMC of the lumbar spine assessed with dual photon absorptiometry. However, the error of estimation of proximal BMC (SEE=20.0%) and distal BMC (SEE=19.4%) made these measurements of little value to predict BMC at the lumbar spine in individuals. The short term reproducibility in patients combined with the long term stability of the equipment in our clinical setting showed that SPA is a reliable technique to assess changes in bone mass at the lower arm of 4% between 2 measurements with a confidence level of 95%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00257547
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    Paper (German National Licenses)
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