A population-based study of bone mineral density in women with longstanding type 1 (insulin dependent) diabetes

This study aimed to explore multiple determinants of BMD (bone mineral density) in 99 women with long-standing type 1 diabetes, recruited from a population based register of insulin users. BMD was measured using DEXA (dual energy X-ray absorptiometry) at the femoral neck and lumbar spine, age adjusted Z scores were calculated and results compared to those of healthy volunteers. The median age of diabetic subjects was 42 years and the median duration of diabetes was 27 years. BMD was positively associated with body mass index and height at both the lumbar spine and femoral neck. There was a positive association with oral contraceptive pill use and lumbar spine BMD, and peripheral vascular disease was negatively associated with femoral neck BMD. No correlation was seen with either age or duration of diabetes and absolute BMD values. Mean Z score at the femoral neck was -0.12 (95% confidence interval -0.37 to +0.12). At the lumbar spine, the corresponding value was -0.21 (-0.44 to +0.02). Pre- and post-menopausal values for the diabetic subjects and healthy volunteers were found to be similar. In summary, axial BMD values in subjects with long-standing diabetes were similar to those observed in healthy non diabetic populations.

The effect of socioeconomic status on bone density in a male Caucasian population

We have examined the effect of socioeconomic status (SES) on bone density (BMD) in 201 males, aged 20-60 years. Males of lower SES (groups 4-6 vs. 1-3) from the total sample had significantly higher BMD (p < 0.05) at L2-4 and femoral neck. The difference was small but was not explained by differences in age, weight, calcium intake, family history, activity, or smoking. 45% of SES 4-6 males were involved in manual labor compared with 11% of those in SES 1-3, however, this also did not appear to account for the difference.

The added effectiveness of early geriatrician involvement on acute orthopaedic wards to orthogeriatric rehabilitation

AIMS

To evaluate the effect of regular input by a geriatrician to an orthopaedic ward.

METHOD

A geriatrician saw all patients aged over 65 years admitted to an acute orthopaedic ward-this was compared to an adjacent orthopaedic ward which had consultation only service, and also to both wards in the preceding year. All subjects over the age of 65 years with fractured neck of femur admitted over a 4 month period were enroled. Main outcome measures were length of stay, cost, discharge destination.

RESULTS

In the year prior to study, patients in both wards had a mean total stay of 28 days. On the intervention ward the mean stay was reduced to 20.7 days, and on the control ward to 27 days. The cost per case on the intervention ward was NZ$9400, and on the control ward was NZ$11 500. Eleven percent went to a higher care level on the intervention ward, compared with 23% on the control ward.

CONCLUSION

Geriatrician input on a twice weekly basis to all patients over 65 years of age on an orthopaedic ward, saves bed days, reduces costs and produces an improved outcome.

Bone mineral density is reduced in female but not male subjects with Addison's disease

AIMS

Bone mineral density (BMD) may be potentially reduced in Addison's disease as a result of excessive glucocorticoid replacement, loss of adrenal androgens or concomitant gonadal or thyroid disease. We have examined clinical and biochemical parameters, and BMD in a group of subjects with Addison's disease.

METHODS

Fourteen patients (9 female mean age 56 years, 5 male mean age 56.6 years) with primary adrenocortical failure (median duration 8.5 yrs) on replacement therapy were studied. Four had hypothyroidism on thyroxine doses (0.1 to 0.15 mg/d). Seven of the 9 females were post menopausal. Mean plasma cortisol levels were calculated from at least five samples in each subject drawn between 3 and 5 hours post dose, and the cortisol replacement dose calculated per unit body mass (mg/kg). BMD was measured by dual energy X-ray absorptiometry (DEXA) at femoral neck and lumbar spine (L2-4) and compared with local reference data.

RESULTS

For women (n = 9) at L2-4 the mean Z score was -1.21 (95% CI -1.69, -0.73), and at femoral neck -0.57 (95% CI -1.15, 0.00). For men (n = 5) at L2-4, the mean Z score was 1.32 (95% CI -0.86, 3.50) and at femoral neck 0.62 (95% CI -0.18, 1.42). For all patients, there was no significant correlation between mean plasma cortisol and Z scores at L2-4 and femoral neck, r = -0.003 and -0.095 respectively; and between duration of Addison's disease and mean Z scores at L2-4 and femoral neck r = -0.043 and 0.143 respectively.

CONCLUSIONS

Women with Addison's disease therefore have a greater than expected reduction in BMD. We postulate that this may be related to loss of adrenal androgens.

Bone mineral density in patients receiving suppressive doses of thyroxine for thyroid carcinoma

AIMS

Studies of the effect of thyroxine therapy on skeletal integrity have given conflicting results; the reductions in bone mass reported by some have prompted recommendations that the prescribed replacement doses of thyroxine should be reduced. We have examined bone mineral density in a group of patients with differentiated thyroid carcinoma receiving high doses of thyroxine to suppress thyroid stimulating hormone (TSH).

METHODS

The 44 patients (6 male, 38 female) had a median age of 49 years (range 27-75) with median duration of thyroxine therapy of 9.0 years (range 3 to 42) and mean dose of thyroxine 0.167 mg/day (range 0.125-0.3). TSH levels were chronically suppressed in 39 subjects. Bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DEXA) in all subjects at the femoral neck and lumbar spine and compared with previously established local reference ranges.

RESULTS

There was no reduction in bone mineral density in the thyroxine treated group compared with the local reference population at both lumbar spine and femoral neck, and no correlation with duration of therapy.

CONCLUSIONS

These negative findings, that thyroxine in suppressive doses does not significantly reduce bone mineral density in New Zealand patients suggest that thyroxine therapy alone is not a major risk factor for the development of osteoporosis.

Historical assessment of risk factors in screening for osteopenia in a normal Caucasian population

BACKGROUND

Bone mineral density (BMD) can predict fracture, however, the common use of historical risk factors to predict low BMD is unproven.

AIMS

To identify significant historical risk factors for osteopenia. To establish predicting equations for BMD and test their ability to identify those who should be referred for BMD scanning.

METHODS

Three hundred and twenty female and 131 male volunteers underwent questionnaire assessment of risk factors and BMD by dual photon absorptiometer at hip and spine. Significant risk factors (P < 0.05) were used to construct a linear regression model to predict BMD. This was cross validated on a second sample of 107 females and 131 males selected from the electoral roll analysing the ability to detect those subjects with BMD in the lower third of the age matched normal range.

RESULTS

In women lower BMD at the spine was associated with increased age, decreased weight, smoking, and delayed menarche. Lower femoral BMD was associated with increased age, decreased weight, family history, inactivity, and smoking. In men lower BMD at the lumbar spine was associated with lower weight, and inactivity. Lower BMD at the femur was associated with increased age, decreased weight, family history, and low calcium intake. When cross validated on the second sample, the models produced sensitivity of 86-89% and sensitivity of 25-46%. Referring those with these risk factors could save 10-23% on scanning. Measuring BMD at the site in question remains the only accurate way of assessing an individual's risk of osteopenia.

Asymptomatic low bone mineral density in otherwise healthy people: four year follow up

AIM

To determine the effect of screening a normal population for low bone density on lifestyle, subsequent bone density and fracture risk.

METHOD

A cross sectional study of 726 subjects screened for low bone density identified 60 with bone density greater than one standard deviation below an age and sex matched mean. Those who accepted further assessment were followed clinically and with repeat bone densitometry for up to four years. Those declining assessment were contacted four years later and questioned about lifestyle changes and fractures. They were offered repeat bone densitometry.

RESULTS

Twenty five subjects accepted intervention and were advised on lifestyle modification and treated with calcium supplements (18) calcitriol (5) or oestrogen (1). 22 of the 35 subjects who initially declined intervention volunteered to have their bone density repeated. Bone density increased in the group accepting intervention compared to the 22 subjects in the group who initially declined assessment (p < 0.05). Several laboratory investigations had a low yield. Lifestyle modification in the group declining assessment did not significantly affect subsequent bone density. Fractures occurred infrequently in both groups.

CONCLUSION

After screening the normal population for low bone density, significant improvements in bone density can be achieved in patients accepting further intervention.

A comparison of elderly patients with proximal femoral fractures and a normal elderly population: a case control study

AIM

To assess the importance of bone density and other risk factors in elderly subjects with hip fractures.

METHOD

Thirty-six subjects with femoral neck fracture were compared with 72 community controls in this case control study. Variables compared included: history of falls, previous fracture, body mass index, hand grip strength, blood pressure, medication use, cigarette smoking, alcohol intake, visual acuity, age at menopause, mental status quotient, mobility index and mid thigh circumference. Bone mineral density was measured at the hip (DPA absorptiometer) in the 36 subjects with hip fracture and 36 community controls.

RESULTS

Fracture patients had significantly (p < 0.01) reduced bone mineral density at femoral neck (0.64 vs 0.74 g/cm2) and trochanteric regions (0.55 vs 0.66 g/cm2). They also had significantly (p < 0.05) lower body mass index, weaker hand grip strength, smaller mid thigh circumference, reduced mobility and more previous fractures. After controlling for age and sex stepwise logistic regression identified handgrip strength, mobility status and falls in that ranking as risk factors for fracture. Bone mineral density was correlated with mobility status and grip strength.

CONCLUSION

Patients with hip fracture have lower bone mineral density than controls. Mobility, grip strength and muscle bulk appear to be important in fracture aetiology and could operate either through bone density or risk of falling.

Assessment of creatinine clearance in healthy subjects over 65 years of age

Eighteen healthy people over 65 years of age were studied to compare the 99mTC-diethylenetriamine pentaacetic acid (DTPA) clearance, the measured 24-hour creatinine clearance and the assessed creatinine clearance using the Cockcroft and Gault (C-G) formula to measure their glomerular filtration rate. Significant correlations were found between the isotopic method and the measured creatinine clearance (r = 0.71; p less than 0.001); the measured creatinine clearance and the C-G formula (r = 0.81; p less than 0.001), and the isotopic method and the C-G formula (r = 0.70; p less than 0.001). The C-G formula correlated better with both the 99mTc-DTPA clearance and the measured creatinine clearance when the female correction factor was used. This study has shown that in healthy, elderly people, the C-G formula for assessing the creatinine clearance correlated extremely well with the standard clinical tests for measuring the glomerular filtration rate. Whilst the formula has clinical value and allows rapid and accurate assessment of renal function in the elderly, the clinician must be aware that the formula relatively underestimates the true renal clearance.