Dessa Gemar

Evaluation of Ergocalciferol or Cholecalciferol Dosing, 1,600 IU Daily or 50,000 IU Monthly in Older Adults

CONTEXT Whether ergocalciferol (D(2)) and cholecalciferol (D(3)) are equally effective to increase and maintain serum 25-hydroxyvitamin D [25(OH)D] concentration is controversial. OBJECTIVE The aim of the study was to evaluate the effect of daily and once monthly dosing of D(2) or D(3) on circulating 25(OH)D and serum and urinary calcium. DESIGN, SETTING AND PARTICIPANTS In a university clinical research setting, 64 community dwelling adults age 65+ were randomly assigned to receive daily (1,600 IU) or once-monthly (50,000 IU) D(2) or D(3) for 1 yr. MAIN OUTCOME MEASURES Serum 25(OH)D, serum calcium, and 24-h urinary calcium were measured at months 0, 1, 2, 3, 6, 9, and 12. Serum PTH, bone-specific alkaline phosphatase, and N-telopeptide were measured at months 0, 3, 6, and 12. RESULTS Serum 25(OH)D was less than 30 ng/ml in 40% of subjects at baseline; after 12 months of vitamin D dosing, levels in 19% of subjects (n = 12, seven receiving daily doses and five monthly doses) remained low, despite compliance of more than 91%. D(2) dosing increased 25(OH)D(2) but produced a decline (P < 0.0001) in 25(OH)D(3). Substantial between-individual variation in 25(OH)D response was observed for both D(2) and D(3). The highest 25(OH)D observed was 72.5 ng/ml. Vitamin D administration did not alter serum calcium, PTH, bone-specific alkaline phosphatase, N-telopeptide, or 24-h urine calcium. CONCLUSIONS Overall, D(3) is slightly, but significantly, more effective than D(2) to increase serum 25(OH)D. One year of D(2) or D(3) dosing (1,600 IU daily or 50,000 IU monthly) does not produce toxicity, and 25(OH)D levels of less than 30 ng/ml persist in approximately 20% of individuals. Substantial between-individual response to administered vitamin D(2) or D(3) is observed.

Vertebral fracture assessment: impact of instrument and reader

PurposeMany osteoporotic vertebral fractures are not clinically recognized but increase fracture risk. We hypothesized that a newer generation densitometer increases the number of evaluable vertebrae and vertebral fractures detected. We also explored the impact of reader experience on vertebral fracture assessment (VFA) interpretation.MethodsVFA images obtained using Prodigy and iDXA densitometers in 103 older adults were evaluated for vertebral visualization and fracture presence in the T4–L5 region. A “true” read for each densitometer was achieved by consensus. If readers disagreed, the evaluation of a third expert physician was taken as true. Main outcomes were evaluable vertebrae, vertebral fractures, and intrareader/interreader reproducibility.ResultsUsing the “true” reads, 92% of vertebrae were visualized on iDXA and 76% on Prodigy. Numerically, more fractures were identified with iDXA; the “true” reads found 43 fractures on iDXA and 21 on Prodigy. The experienced reader had better intrareader and interreader reproducibility than the inexperienced reader when compared with the “true” read.ConclusionsUsing the newer iDXA densitometer for VFA analysis improves vertebral body visualization and fracture detection. Training and experience enhance result reproducibility.

Use of a questionnaire to assess vitamin D status in young adults

OBJECTIVE We hypothesized that young adults would commonly have vitamin D deficiency and that a questionnaire could help identify subjects with the condition. DESIGN Between January and May 2004, we administered a questionnaire to a convenience sample of young adults. We measured each participants serum level of 25-hydroxyvitamin D (25(OH)D) using a chemiluminescent assay and defined deficiency as serum 25(OH)D < 16 ng/ml. SETTING AND SUBJECTS We recruited young adults living in Madison, Wisconsin without pre-existing conditions affecting vitamin D and/or Ca metabolism. RESULTS One hundred and eighty-four adults (mean age 24 years, 53 % women, 90 % Caucasian) participated in the study. Nearly three in four adults (71 %) had 25(OH)D level <30 ng/ml and 26 % were vitamin D-deficient. In multivariate analysis, persons reporting a suntan (OR = 0.24, 95 % CI 0.09, 0.63, P = 0.004), tanning booth use (OR = 0.09, 95 % CI 0.02, 0.43, P = 0.002) and daily ingestion of two or more servings of milk (OR = 0.21, 95 % CI 0.09, 0.48, P < 0.001) were less likely to be deficient. These three questions provided a sensitivity and specificity of 79 % and 78 %, respectively, for the presence of deficiency. CONCLUSIONS The questionnaire is moderately useful to identify young adults likely to be vitamin D-deficient. Additional revisions of the questionnaire may improve its ability to predict vitamin D deficiency.

BMD Measurement and Precision: A Comparison of GE Lunar Prodigy and iDXA Densitometers

This study assessed bone mineral density (BMD) comparability and precision using Lunar Prodigy and iDXA densitometers (GE Healthcare, Madison, WI) in adults. Additionally, the utility of supine forearm measurement with iDXA was investigated. Lumbar spine and bilateral proximal femur measurements were obtained in routine clinical manner in 345 volunteers, 202 women and 143 men of mean age 52.5 (range: 20.1-91.6)yr. Seated and supine distal forearm scans were obtained in a subset (n=50). Lumbar spine and proximal femur precision assessments were performed on each instrument following International Society for Clinical Densitometry recommendations in 30 postmenopausal women. BMD at the L1-L4 spine, total proximal femur, and femoral neck was very highly correlated (r(2)≥0.98) between densitometers, as was the one-third radius site (r(2)=0.96). Bland-Altman analyses demonstrated no clinically significant bias at all evaluated sites. BMD precision was similar between instruments at the L1-L4 spine, mean total proximal femur, and femoral neck. Finally, one-third radius BMD measurements in the supine vs seated position on the iDXA were highly correlated (r(2)=0.96). In conclusion, there is excellent BMD correlation between iDXA and Prodigy densitometers. Similarly, BMD precision is comparable with these two instruments.