Biomedical subjects

Susan A Steel

Publications and source records attributed to Susan A Steel.

3 recordsLinked to original sources

PubMed2006

Vertebral morphometry by DXA: a comparison of supine lateral and decubitus lateral densitometers.

Identification of vertebral fracture has become increasingly important in the diagnosis and management of osteoporosis. This study compares the morphometric techniques on a fan beam dual-energy X-ray absorptiometry (DXA) GE-Lunar Expert system (Expert) using a supine lateral position and a narrow fan beam GE-Lunar Prodigy system (Prodigy; GE Lunar, Madison, WI) that requires lateral decubitus positioning. Patient acceptability, image quality, observer, and equipment variability were determined. Study subjects were recruited from clinical referrals sent for a routine DXA study that included vertebral morphometry. Twenty-five patients underwent lateral vertebral assessment on both machines and completed a questionnaire on comfort and tolerability. Analysis was undertaken by two trained observers. Vertebral height, anterior/posterior height (A/P) and mid/posterior height (M/P) ratios, image quality, and prevalent fractures were assessed. There were no significant differences in patient comfort or image quality scores. More upper thoracic vertebrae could be assessed on the Expert, and good radiographic positioning was easier to achieve on the Expert. Inter-observer coefficients of variance percentage (CV%) of vertebral height was lower on the Prodigy (3.5% in the lumbar spine rising to 12.8% in the thoracic spine) than the Expert (4.2% to 16.9%). Inter-observer CV% for A/P and M/P ratios varied from 2.5% to 10.5% on the Prodigy compared with 3.5% to 12.3% on the Expert, depending on vertebral level. The variation between instruments was similar to the inter-observer CV% (anterior height: -0.11+/-1.65 mm; mid height: 0.54+/-1.51 mm; posterior height: 0.43+/-1.46 mm). There was good agreement between observers and between the Expert and Prodigy in identifying severe fractures, but lack of agreement in identifying moderate fractures. In conclusion, there was no clinically significant difference in patient comfort and image quality between the Expert and the Prodigy. The inter-observer variations in vertebral height and A/P and M/P ratios are similar to the variations between instruments. In making the change from the supine lateral to the decubitus lateral positioning, measurements of vertebral height are reproducible and patient comfort is not compromised.

Absorptiometry, Photon↗

PubMed2006

Bone mineral density and depot medroxyprogesterone acetate.

INTRODUCTION: Depot medroxyprogesterone acetate (DMPA) suppresses pituitary gonadotrophin output, thus, suppressing ovulation. Estrogen production from the ovary is also strongly inhibited, and the resulting estrogen deficiency has a detrimental impact on bone. Depot medroxyprogesterone acetate may be particularly detrimental in young women, as it may impede attainment of peak bone mass, and switching to a different contraceptive is recommended. However, the effect of sequential use of DMPA with other contraceptives in this age group has not been investigated. METHODS: This was a cross-sectional analysis of 218 DMPA users who were 20 years or older (mean, 31 years, +/-8.9 SD) at the time of bone mineral density (BMD) estimation. The majority of women had used one or more contraceptive beside DMPA. The most commonly used alternative contraceptive was the oral combined pill (OCP). It was used by 65% of women (n=143) and for an average duration of 6 years. A logistic regression model was used to estimate the association between potential risk factors and low bone mass. RESULTS: The prevalence of low bone mass at either hip or spine (T< or =1) was 41%. The prevalence of a T score below -2.5 was 5%, and 45% of women had already sustained one fracture. Younger age was associated with higher BMD [odds ratios (ORs), 0.054; 95% confidence interval (CI), 0.007-0.431]. However, this protective effect of age was lost once the interaction between the duration of both DMPA and OCP was introduced into the model (OR for low BMD, 1.42; 95% CI, 1.09-1.8). The use of DMPA first before ever use of OCP was particularly detrimental to BMD (OR, 3.94; 95% CI, 1.08-14.0). On the contrary, body mass index was positively associated with BMD (OR, 0.86; 95% CI, 0.8-0.9). No other demographic or anamnestic variables significantly predicted the presence of low BMD in this group of young women. This group of DMPA users appear to be at a very high risk of both low BMD and fractures, possibly independently of DMPA use. This needs to be considered when writing guidelines for risk assessment. CONCLUSION: The use of DMPA before achievement of peak bone mass may be particularly detrimental to bone, but switching DMPA with the OCP in these women does not seem to confer specific benefit in terms of bone density. This needs to be taken into consideration when a change in contraceptive is considered purely for the sake of bone protection.

Adult↗

PubMed2002

Hyperparathyroidism in elderly osteopenic women.

Raised levels of parathyroid hormones (PTH) predispose to osteoporotic fracture particularly in the elderly. The true prevalence of primary or secondary hyperparathyroidism is unknown, as PTH evaluation is not performed as a screening test in the elderly. We report raised PTH levels in 27 of 190 (14.2%) community living fully mobile postmenopausal women with densitometrically established osteopenia, consuming an average of 645 (+/-191) mg of calcium per day. Twenty-five of the 27 women with raised PTH were normocalcaemic, hypercalcaemia been found only in two. Serum 25 hydroxy vitamin D levels were all within the normal range (above 22 nmol/l). Women with a raised PTH were significantly older and their serum 25 hydroxy vitamin D levels were significantly lower than those women with normal PTH values. These data suggest that in community leaving healthy postmenopausal women, normocalcaemic hyperparathyroidism, in the presence of what are still considered normal vitamin D levels, may be common. This may suggests that widespread supplementation with calcium and vitamin D may be required in postmenopausal women for PTH suppression and preservation of bone mass.

Aged↗