Errors in Patient Positioning for Bone Mineral Density Assessment by Dual X-Ray Absorptiometry: Effect of Technologist Retraining

Improper positioning is one of the factors that can lead to incorrect bone mineral density (BMD) results. This study aimed to assess the frequencies of erroneous positioning during three periods: before retraining of the technologists (BR), after retraining (AR), and at the current timepoint 8 years after retraining (C). The BMD images of the first 150 consecutive patients who underwent DXA of the lumbar spine and hip during each of the three periods were retrospectively reviewed. Patients were excluded if they had severe scoliosis, rendering proper positioning impossible. Each BMD image was assessed by an International Society of Clinical Densitometry certified clinical densitometrist who was blinded to the date of the initial examination. For the lumbar spine in the BR group, the criteria frequently not met were inclusion of both iliac crests (33.8%), straightness (30.3%), and midline positioning (20.4%); the respective frequencies were significantly reduced to 0.8%?5.6%, 2.1%?3.0%, and 0%?2.8% in the AR and C groups (p < 0.05). For the hip in the BR group, the criteria frequently not met were straightness (52.8%) and internal rotation (21.8%); the respective frequencies were significantly reduced to 0%?4.2% and 8.3%?8.4% in the AR and C groups (p < 0.05). Overall improper positioning in the BR group was 49.3% and 57.3% at the lumbar spine and the hip, respectively; the respective frequencies were reduced to 9.3% and 12.7% in the AR group, and to 2.7% and 7.3% in the C group. The least significant change values for the lumbar spine, femoral neck, and total hip also became smaller after retraining. Retraining the technologists improved patient positioning, as evidenced by the decreased frequencies of erroneous positioning and the improved least significant change values after the retraining.     

Causal association pathways between fetuin-A and kidney function: a mediation analysis

ObjectiveBody mass index (BMI), uric acid, diabetes mellitus, and hypertension are risk factors for reduced kidney function and are associated with fetuin-A levels, but their causal pathways remain unclear. The objective of this study was to investigate this knowledge gap.MethodsA repeated cross-sectional design was used to assess causal pathway effects of fetuin-A on the estimated glomerular filtration rate (eGFR), which is mediated through BMI, uric acid, diabetes mellitus, and hypertension.ResultsAmong 2305 participants, the mean eGFR at baseline decreased from 98.7 ± 23.6 mL/minute/1.73 m² in 2009 to 92.4 ± 22.9 mL/minute/1.73 m² in 2014. Fetuin-A was significantly associated with eGFR , suggesting that increasing fetuin-A levels predict a decrease in eGFR. Additionally, the indirect effect of fetuin-A on eGFR, as assessed through BMI, was also significant. The effects of fetuin-A on eGFR through other mediation pathways showed variable results.ConclusionsOur study revealed a possible role of fetuin-A in the etiology of declining renal function through mediating body mass index, uric acid, diabetes mellitus, and hypertension via complex causal pathways. Further studies to clarify these mediated effects are recommended.     

Antimicrobial resistance in Burkholderia pseudomallei

Four strains of Burkholderia pseudomallei were used to determine the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill curves with 13 single antimicrobial agents: ceftazidime, piperacillin, imipenem, amoxicillin/clavulanic acid, doxycycline, cotrimoxazole, kanamycin, rifampicin, ciprofloxacin, trovafloxacin, clarithromycin, azithromycin and meropenem. The time-kill studies were also performed with 33 pairs of combinations of the above antimicrobial agents: 15 combinations which would be expected to be used for acute therapy and 18 combinations for maintenance therapy. The results show that the single and combination antimicrobial agents with bactericidal effects against the four strains of B. pseudomallei which should be used for clinical trials in acute melioidosis are: imipenem, meropenem, and imipenem + azithromycin. The combination antimicrobial agents which should be further studied for the ability to eliminate biofilm and intracellular killing effect are ciprofloxacin + clarithromycin, ciprofloxacin + azithromycin, and imipenem + azithromycin.     

A specific haplotype in the 3′ end of estrogen-receptor alpha gene is associated with low bone mineral density in premenopausal women and increased risk of postmenopausal osteoporosis

It is well established that the development of postmenopausal osteoporosis is under genetic influence. We have recently identified a synonymous single nucleotide polymorphism (SNP) in exon 8 of estrogen receptor- (ER) gene in the vicinity of the stop codon (G2014A) that is associated with an increased risk of postmenopausal osteoporosis. In the present study, we attempted to locate SNPs in the 3-unstranslated region (3UTR) of the ER gene that are in linkage disequilibrium with the exon 8 SNP and assessed their utilization in the risk assessment of postmenopausal osteoporosis in 352 Thai postmenopausal women. The association with bone mineral density (BMD) in premenopausal women was also investigated in 202 premenopausal women. A C to A SNP 1,748 nucleotides distal to the end of the stop codon (C3768A) was identified. The C3768A SNP was not overrepresented in subjects with osteoporosis. However, the presence of the A-C haplotype allele based on the A2014 and C3768 alleles was significantly related to the risk of osteoporosis independently of age, body weight, the G2014A and C3768A SNPs (odds ratio 2.36, 95% CI 1.42–3.91). Moreover, the presence of the A-C haplotype allele was associated with lower femoral neck BMD in premenopausal women ( P =0.05). We concluded that a specific haplotype in the 3 end of the ER gene is associated with lower BMD in premenopausal women and is associated with a higher risk of osteoporosis in postmenopausal women. It is likely that the haplotype allele exerts its influence on bone as early as during young adulthood to increase the risk of osteoporosis later in life.     

Exogenous subclinical hyperthyroidism during adolescence: effect on peak bone mass

BACKGROUND: Chronic subclinical hyperthyroidism induced by suppressive doses of L-thyroxine (L-T4) therapy, so-called exogenous subclinical hyperthyroidism, may cause diminished bone mass in postmenopausal women. The effect of subclinical hyperthyroidism during childhood and adolescence on peak bone mass, however, has not been evaluated. OBJECTIVE: To determine whether exogenous subclinical hyperthyroidism during adolescence, the period of critical bone mass acquisition, would reduce peak bone mass. PATIENTS AND METHODS: Eighteen female adolescents and young adults with Hashimoto's thyroiditis and euthyroid goiter (aged 22.4 +/- 4.4 years) who had been treated with suppressive doses of L-T4, 127.5 +/- 23.7 microg/day, during adolescence (age at onset of subclinical hyperthyroidism, 14.2 +/- 1.5 years) for 6.3 +/- 3.4 years were enrolled in the study. Twenty-nine healthy female volunteers matched for age, weight, height and body mass index served as the controls. Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. Results: BMD of the lumbar spine, radius, Ward's triangle and total body were comparable in the two groups. In contrast, BMD of the femoral neck, trochanter and shaft of patients was slightly higher than those of controls. There were no correlations between BMD values and clinical parameters. CONCLUSION: Exogenous subclinical hyperthyroidism during adolescence has no demonstrable detrimental effect on peak bone mass attainment.     

Risk of Calcium Oxalate Nephrolithiasis after Calcium or Combined Calcium and Calcitriol Supplementation in Postmenopausal Women

Although calcium supplementation can cause hypercalciuria, the risk of nephrolithiasis has been shown to decrease rather than increase among subjects who had a higher calcium intake. Hypercalciuria is also a well-established side effect of calcitriol administration. However, the risk of nephrolithiasis is not well defined. The present study was undertaken to prospectively determine the effect of calcium with or without calcitriol on physicochemical risk factors associated with calcium oxalate nephrolithiasis in Thai postmenopausal women with osteoporosis. Subjects consisted of 53 Thai women more than 10 years postmenopausal who were randomly allocated to receive 750 mg of calcium carbonate supplement alone (n= 28) or 750 mg of calcium carbonate plus 0.5 mg calcitriol (n= 25) daily. Mean ± SEM for age was 65.3 ± 1.1 years, body weight 53.5 ± 1.3 kg. Urine samples for biochemical assays were collected at baseline and 3 months after treatment. Supersaturation for calcium oxalate stone formation was assessed from the 24 h urine constituents by the Tiselius’s index, AP(CaOx). Three months of calcium supplement alone resulted in a modest, but not significant, increase in urinary calcium (baseline, 2.90 ± 0.43 mmol/day; after treatment 3.58 ± 0.54 mmol/day) with no change in urinary oxalate, citrate or magnesium. In contrast, calcium together with calcitriol caused a significant increase in urinary calcium (baseline, 2.87 ± 0.41 mmol/day; after treatment, 4.08 ± 0.57 mmol/day; p<0.05). No significant change in other urine constituents after treatment with calcium and calcitriol was detected. Therefore, AP(CaOx) did not significantly increase either after calcium alone (baseline, 1.17 ± 0.39; after treatment, 1.36 ± 0.28) or after calcium plus calcitriol (baseline, 1.09 ± 0.17; after treatment, 1.09 ± 0.19). However, after treatments, 12 subjects (23%) – 6 receiving calcium supplement alone and 6 receiving calcium plus calcitriol supplement – had high AP(CaOx) values (greater than the upper limit of 95% CI for AP(CaOx) derived from non-stone-forming Thai women). The post-treatment/baseline ratio was 3.21 ± 0.74 for urinary calcium, 1.01 ± 0.19 for urinary oxalate, and 2.23 ± 0.42 (median 1.15) for AP(CaOx). The post-treatment/baseline ratio of calcium, but not for urinary oxalate, had a significant correlation with the post-treatment/baseline ratio of AP(CaOx). Our findings suggest that the alteration in the risk of calcium oxalate nephrolithiasis based on urinary composition is related to the alteration in urinary calcium. The risk of calcium oxalate nephrolithiasis does not increase significantly after calcium or combined calcium and calcitriol supplement in the majority of postmenopausal women with osteoporosis. Received: 10 March 1999 / Accepted: 16 November 1999     

Discrepancy of left and right hip bone mineral density (BMD) in Thai women: diagnostic agreement and misclassification

Objective

To determine the diagnostic agreement and the degree of misclassification when using data from the left and right hips.

Methods

The cross-sectional study of 1,943 perimenopausal and postmenopausal Thai women, who had bone mineral density (BMD) measurements at the left (non-dominant) and right hips for the screening of low bone mass (LBM) or osteoporosis (OP) in the Department of Radiology, Faculty of Medicine, Chiang Mai University from September 2008 to August 2010 was performed. The kappa statistic was used to assess diagnostic agreement. The prevalence of LBM and OP and the percentage of misclassification were reported.

Results

There was a significant correlation between the left and right BMD values for the femoral neck (FN) (r ²?=?0.83; p?<?0.001) and the total hip (TH) (r ²?=?0.89; p?<?0.001). The diagnostic agreement of the FN and TH regions was significant in all study groups ranging from 0.69 to 0.76 (p?<?0.001). For the final diagnosis, which is based on the least T-score of the FN or TH regions, the diagnostic agreement was 0.73 for all women, 0.77 for perimenopausal women, 0.73 for postmenopausal women, 0.70 for postmenopausal women age less than 65?years and 0.71 for postmenopausal women age greater than or equal to 65?years. The percentage of misclassification for all women was 16.9?%, with 3.3?% being downgraded from normal to LBM and 3.4?% from LBM to OP.

Conclusion

Despite the fact that good diagnostic agreement was demonstrated in this study, a significant number of diagnostic discordance between left and right hips (16.9?%) was also observed. BMD measurements of both hips are recommended for diagnosing LBM and OP in clinical practice.     

Importance of ethnic base standard references for the diagnosis of osteoporosis in Thai women

Many studies demonstrated the importance of using ethnic-specific normal database in the diagnosis of osteoporosis (OP). Aims of this study were to assess diagnostic agreement, prevalence of OP, and diagnostic misclassification between Caucasian, Japanese, and Thai normal databases. The cross-sectional study of 3181 Thai women who had bone mineral density (BMD) measurement between January 2008 and December 2010 was performed. BMDs at lumbar spine (LS), femoral neck (FN), and total hip (TH) were derived to T-score by using Caucasian, Japanese, and Thai standard references. Kappa statistic was used to assess diagnostic agreement and misclassification. Diagnostic agreements between Caucasian and Thai reference databases were 0.39 for LS and 0.90 for FN. No statistical agreement was found in TH region (0.01, p value=0.264). Applying the Japanese reference, diagnostic agreements were 0.71 for LS, 0.76 for FN, and 0.94 for TH regions. Prevalence of OP in postmenopausal women was 64.1%, 37.7%, and 41.4% using Caucasian, Japanese, and Thai standard references. Percentage of misclassification was varied by menopausal status and reference database from 11.2% to 48.7%. When applying Japanese databases instead of Caucasian normal databases, overall diagnostic misclassification decreased from 35.1% to 16.1%. Choice of reference database has a significant effect on the diagnosis of low bone mass and OP. Japanese reference database has better diagnostic agreement with previously studied Thai reference database in 1999 than Caucasian reference database.