Efficacy of Bolus Calculation and Advanced Carbohydrate Counting in Type 2 Diabetes: A Randomized Clinical Trial

Background: Carbohydrate counting and use of automated bolus calculators (ABCs) can help reduce HbA_1c in type 1 diabetes but only limited evidence exists in type 2 diabetes. We evaluated the efficacy of advanced carbohydrate counting (ACC) and use of an ABC compared with manual insulin bolus calculation (MC) in persons with type 2 diabetes. Materials and Methods: A 24-week open-label, randomized clinical study was conducted in 79 persons with type 2 diabetes treated with basal-bolus insulin (mean age 62.5 ± 9.6 years, HbA_1c 8.7% ± 1.0% [72 ± 11 mmol/mol], diabetes duration 18.7 ± 7.6 years). Participants were randomized 1:1 into two groups: ABC group received training in ACC and use of an ABC; MC group received training in ACC and manual calculation of insulin bolus. Participants wore blinded continuous glucose monitors for 6 days at baseline and at study end. Primary endpoint was change in HbA_1c. Results: After 24 weeks, HbA_1c decreased 0.8% (8.8 mmol/mol) in ABC group and 0.8% (9.0 mmol/mol) in MC group with no between-group difference (P = 0.96) and without increase in time in hypoglycemic range (sensor glucose <3.9 mmol/L). Glycemic variability decreased significantly in both groups, whereas the total insulin dose and body mass index (BMI) remained unchanged during the study. Treatment satisfaction increased significantly in both groups after 24 weeks. Conclusion: ACC is an effective, low-cost tool to reduce HbA_1c and glycemic variability in persons with basal-bolus insulin-treated type 2 diabetes without increase in hypoglycemia or BMI. Similar effects were seen with use of an ABC and with use of manual bolus calculation. Trial registration: ClinicalTrials.gov NCT02887898.

Efficacy of basal-bolus insulin regimens in the inpatient management of non-critically ill patients with type 2 diabetes: A systematic review and meta-analysis

Hyperglycemia during hospitalization is associated with increased rates of complications and longer hospital stays. Various insulin regimens are used in the inpatient diabetes management of non-critically ill patients. In this systematic review and meta-analysis, we aimed to assess the efficacy and safety of basal-bolus insulin therapy (BBI) by summarizing evidence from studies of BBI versus sliding scale insulin therapy (SSI) in the management of hospitalized non-critically ill type 2 diabetes patients. We searched MEDLINE, EMBASE, Scopus, and the Cochrane Library for studies comparing BBI therapy with SSI therapy in hospitalized non-critically ill patients with type 2 diabetes. Primary outcome was mean daily blood glucose (BG) during admission. Secondary outcomes were incidence of hypoglycemia and length of hospital stay. Results of included randomized controlled trials (RCT) were pooled and meta-analysed to provide estimates of the efficacy of BBI therapy. Five RCTs and seven observational studies were included in the review. Meta-analysis of RCTs showed significantly lower mean daily BG with BBI than SSI. Mean difference in daily BG between the two regimens ranged from 14 to 29 mg/dl. BBI therapy was associated with increased risk of mild hypoglycemia (BG ≤ 70 mg/dl, RR 5.75; 95% CI 2.79-11.83), (BG ≤ 60 mg/dl, RR 4.21; 95% CI 1.61-11.02) compared with SSI therapy. There was no difference in risk of severe hypoglycemia (BG ≤ 40 mg/dl) and no difference in mean length of stay. In conclusion, basal-bolus insulin in the inpatient diabetes management results in significantly lower mean daily BG than sliding scale insulin but is associated with increased risk of mild hypoglycemia.

Are soft tissue composition of bone and non-bone pixels in spinal bone mineral measurements by DXA similar? Impact of weight loss

Weight loss seems associated with a decrease in bone mineral density (BMD) as measured by absorptiometry, which may be the result of accuracy errors caused by differences in soft tissue between non-bone and bone pixels. The aim was to study the abdominal fat% and thickness in regions corresponding to non-bone, soft tissue-only and bone pixels for spinal BMD measurements by dual energy X-ray absorptiometry (DXA), and to calculate the theoretical errors in measurement of changes in BMD by DXA as a result of changes in soft tissue heterogeneity with weight loss. Abdominal computed tomography (CT) and DXA scans were performed in 34 obese subjects (42.1+/-10.1 years (mean +/- SD), wt: 102.1+/-12.8 kg and BMI: 36.6+/-3.8 kg m(-2)) before and after weight loss (11.3+/-6.9 kg after 1 year). There were some significant differences in fat% and thickness of soft tissue between abdominal regions corresponding to non-bone and bone pixels, respectively, for spinal BMD measurements by DXA, both before and after weight loss. With weight loss there were some changes in the soft tissue heterogeneity, which caused a minor theoretical error (apparent, but false decrease of 1-2%) of borderline significance for the anterior-posterior (AP) spinal BMD by DXA.

Influence of orlistat on bone turnover and body composition

OBJECTIVE

To investigate the influence of the pancreas lipase inhibitor orlistat (OLS) on calcium metabolism, bone turnover, bone mass, bone density and body composition when given for obesity as adjuvant to an energy- and fat-restricted diet.

DESIGN

Randomized controlled double-blinded trial of treatment with OLS 120 mg three times daily or placebo for 1 y.

SUBJECTS

Thirty obese subjects with a mean body mass index (BMI) of 36.9+/-3.7 kg/m(2) and a mean age of 41+/-11 y. Sixteen patients were assigned to OLS and 14 to placebo.

MEASUREMENTS

Dual energy X-ray absorptiometry (DXA) measurements of bone mineral and body composition included total bone mineral content (TBMC), total bone mineral density (TBMD), lumbar spine BMC and BMD, forearm BMC and BMD, fat mass (FM), fat free-mass (FFM), percentage fat mass (FM%) as well as a DXA estimate of the body weight. Body composition (FM, FFM and FM%) was estimated by total body potassium (TBK). Indices of calcium metabolism and bone turnover included serum values of ionized calcium (Ca(++)), iPTH (parathyroid hormone), alkaline phosphatase, 25(OH)-vitamin D, 1,25(OH)(2) vitamin D and osteocalcin as well as fasting urinary ratios of hydroxyproline/creatinine and Ca/creatinine (fU-OHpr/creat, fUCa/creat).

RESULTS

There were no significant differences between OLS and placebo groups as to any of the body composition variables (FFM, FM, FM%) at baseline or after 1 y treatment. Weight loss was of 11.2+/-7.5 kg in the OLS group and 8.1+/-7.5 kg in the placebo group (NS). The changes in FM and FM% were significant in both groups determined by DXA as well as by TBK, but the group differences between these changes were not significant. The composition of the weight loss was approximately 80% fat in both groups. FFM only changed significantly by DXA in the OLS group (-1.3 kg), but the difference from the placebo group was not significant. Forearm BMD in both groups, forearm BMC in the OLS group and TBMD in the placebo group fell discretely but significantly, but there were no significant group differences between the OLS and the placebo-treated group. All biochemical variables except s-osteocalcin changed significantly after 1 y in the OLS group, disclosing a pattern of an incipient negative vitamin D balance, a secondary increase in PTH-secretion, and an increase in bone turnover with the emphasis on an increase in resorption parameters (fU-OHpr/creat, fUCa/creat). In the placebo group, only s-25(OH)vitamin D and fU-OHpr/creat changed significantly, but the pattern was also that of a deteriorated vitamin D status and an increase in PTH levels and bone turnover. The only biochemical variable which was significantly different between OLS and placebo groups after one year was the fU-OHpr/creat ratio, which increased from 12.0 to 20.1 in the OLS group but only from 10.9 to 1 3.2 in the placebo group.

CONCLUSION

One year's treatment with OLS induces a lipid malabsorption which enhances a dietary weight loss without any significant deleterious effects on body composition. OLS induces a relative increase in bone turnover in favour of resorption, possibly due to malabsorption of vitamin D and/or calcium. However, no changes in bone mass or density are seen after 1 y of OLS treatment apart from those explained by the weight loss itself. Thus 1 y of OLS treatment seems safe from a 'bone preserving' point of view. A vitamin D and calcium supplement should be taken during the treatment.

Fasting gall bladder volume and lithogenicity in relation to glucose tolerance, total and intra-abdominal fat masses in obese non-diabetic subjects

OBJECTIVE

To investigate whether total body fat mass or fat distribution and associated metabolic disturbances in glucose and lipid metabolism influence the well known gallstone pathogenetic factors in obese subjects in order to explain why some obese subjects develop gallstones and some do not.

DESIGN

Cross sectional study of gallstone pathogenetic factors, body composition, fat distribution, glucose and lipid metabolism.

SUBJECTS

57 healthy overweight subjects (aged 26-64y, body mass index (BMI) 30-45 kg/m2).

MEASUREMENTS

Total and intra-abdominal fat masses were measured by dual X-ray absorptiometry and abdominal CT scanning, respectively. The lithogenic index was measured in aspirated bile. The gallbladder volume was determined by ultrasound and the gallbladder ejection fraction% by dynamic cholescintigraphy. Plasma cholecystokinin (CCK) concentrations during a meal were measured with a specific radioimmunoassay. Insulin sensitivity was measured by the Minimal Model and glucose tolerance by an oral glucose tolerance test (OGTT). Serum lipid concentrations were measured by standard methods.

RESULTS

The gallbladder volume in the fasting state increased with increasing intra-abdominal fat mass (P=0.006) and was increased in subjects with impaired glucose tolerance (41 vs 27 ml, P=0.001). The lithogenic index was > 1 in all subjects and correlated with total fat mass (P=0.04).

CONCLUSION

Gallstone pathogenesis in obesity seems to be influenced by the total body fat mass and its regional distribution possibly via mutual association with the glucose tolerance.

Body composition analysis by DEXA by using dynamically changing samarium filtration

Dual-energy X-ray absorptiometry (DEXA) has a high accuracy for body composition analysis but is influenced by beam hardening and other error sources in the extremes of measurement. To compensate for beam hardening, the Norland XR-36 introduces a dynamically changing samarium filtration system, which depends on the current-absorber thickness. With this system we found a good agreement (r = 0.99) between reference and measured amounts of tissue or fat percentages in a plastic phantom and in smaller (approximately 0.5-4 kg) and larger (approximately 5-20 kg) piles of tissue (ox muscle and lard). Scans of six healthy volunteers covered with combinations of beef and lard (approximately 5-15 kg) showed a good agreement (r = 0.99) between reference and DEXA values of added soft tissue mass and fat percentage. We conclude that the DEXA method (and, in particular, the Norland XR-36 using dynamic filtration) has a high accuracy for body composition analysis. It has a potential for gaining status as a reference method in the future and may presently be used as a supplement to the traditional methods for body composition analysis.

Body composition during weight loss in obese patients estimated by dual energy X-ray absorptiometry and by total body potassium

OBJECTIVE

To validate the ability of DXA to measure total body composition before and after weight loss and the composition of the lost body mass.

DESIGN

Cross sectional and follow-up study of body composition before and after a weight loss of 10.6 +/- 6.8 kg.

SUBJECTS

31 obese subjects with a mean body weight of 105.2 +/- 15.2 kg at baseline, and a mean body weight of 94.6 +/- 16.5 kg at follow-up.

MEASUREMENTS

Body composition was measured by dual X-ray absorptiometry, total body potassium counting, and high precision scales before and after a weight loss.

RESULTS

DXA and the scales showed a strong linear relation (r = 1). At baseline, however, DXA underestimated the body weight by a maximum of 3.2 kg because the subjects were too large for the scan table. After weight loss body weight measurements were accurate. Before and after weight loss the linear relations between DXA and TBK for FFM were strong (r = 0.92 and 0.93). Bland and Altman plots showed limits of agreement of +/-9 kg before and after weight loss; DXA underestimated FFM in women and overestimated FFM in men. DXA accounted for 80% of the lost body weight. The composition of the lost body mass did not differ from that estimated by TBK (7.6% FFM and 92.4% FM by TBK; 11% FFM and 89% FM by DXA).

CONCLUSION

DXA estimates accurately the body composition and the composition of weight loss in groups of obese subjects. However, the scan table may be too small for patients weighing more than 95 kg.

Change in fat-free mass assessed by bioelectrical impedance, total body potassium and dual energy X-ray absorptiometry during prolonged weight loss

A total of 16 obese women (body mass index (BMI) 30-43 kg m(-2)) participated in a weight reduction study. Before and after a weight loss of 11.7 +/- 7.4 kg (mean +/- SD), body composition was assessed by dual energy X-ray absorptiometry (DXA), and total body potassium counting (TBK). These measurements were compared with bioimpedance analysis (BIA) by applying 11 predictive BIA equations published in the literature. Predictive equations for the present study population were developed, with the use of fat-free mass (FFM) as assessed by TBK and DXA as references in multiple regression analysis. The results of the BIA equations varied widely; FFM was generally overestimated by BIA as compared with DXA and TBK before and after weight loss. During weight loss, the FFM did not change, as estimated by DXA (1.3 +/- 2.3 kg, p > 0.05) and TBK (0.9 +/- 2.9 kg, p > 0.05). The recorded change in impedance (R) was also insignificant. Three BIA equations from the literature, which were not specific for the degree of obesity in the present study group, predicted changes in FFM (from 0.5 + 3.6 to 2.4 +/- 4.4kg, p > 0.05) that were comparable with those estimated by the reference methods. Eight equations from the literature, which included equations specific for the degree of obesity in the study group, and the group specific equations developed for the present population predicted significant changes in FFM during weight loss (from 2.3 +/- 3.0 to 5.0 +/- 3.0 kg, p < 0.05). We conclude that in obesity most predictive equations are unable to predict static body composition and are not reproducible for individuals over time. However, a significant or insignificant change in R (without accompanying predictive equations) may be used to indicate whether FFM is lost or preserved in groups of obese subjects.

Body composition in normal subjects: relation to lipid and glucose variables

OBJECTIVE

To describe sex- and age-dependent values of total and regional body composition as determined by dual-energy X-ray absorptiometry (DXA) in normal subjects, and furthermore to relate body composition measurements to blood lipids, glucose and insulin concentrations.

DESIGN

A cross-sectional study.

SUBJECTS

173 (84 male and 89 female) healthy subjects, BMI < 30 kg/m2.

MEASUREMENTS

Body composition parameters including data on total bone mineral content (TBMC), total bone mineral density (TBMD), lean body soft tissue mass (LTM), total and regional fat mass (FM) were estimated in all subjects. In 87 of the subjects fasting blood glucose, S-insulin and lipid profile were measured.

RESULTS

The study population was for each sex divided into five decades for which results on body composition and blood lipids are presented. Body weight increased 2 kg per age decade, representing a significant increase in both total FM and relative FM (FM%BW) with age, and in males a central accumulation of FM. LTM decreased significantly in males but not in females, whereas TBMC and TBMD remained constant in males, but decreased in females. A significant correlation between relative FM and S-cholesterol, S-triglyceride, and in males S-insulin was found.

CONCLUSION

The present study gives coherent data on bone mineral content, lean body soft tissue mass total and regional fat mass for 173 healthy subjects with a BMI below 30 kg/m2. Total body fat mass increases, and lean mass decreases with age. In males a simultaneous central accumulation of fat mass is observed. The well-known relationship between central obesity and lipids is confirmed even in non-obese subjects.

Comparison of body composition by dual energy X-ray absorptiometry to other estimates of body composition during weight loss in obese patients with rheumatoid arthritis

Body composition was determined by dual energy X-ray absorptiometry (DXA) scanning and classical reference methods (40K, 3H2O, and a combination of these in a four-compartment model) in 19 overweight patients with rheumatoid arthritis who underwent a 12-week weight-reducing regimen. The aim of the study was to investigate whether DXA provides a valid estimate of body composition. The results showed that weight as determined by DXA was highly significantly correlated to weight determined by scales. Furthermore, significant correlations were found in the body components (fat-free mass, fat mass) determined by DXA, 40K, 3H2O and the four-compartment model. Mean values differed slightly but significantly. With respect to changes in body composition, no significant correlations were found between any of the methods, except for the weight loss recorded by DXA and scales, and loss of fat mass (and fat free mass) estimated by 3H2O and the four-compartment model. The sparseness of correlations reflected the small changes in fat-free mass and fat mass (2.6 and 1.7 kg respectively), and the fact that changes were comparable to measurement errors of the various methods. We suggest that DXA scanning is a valid supplement for determination of body composition. Validation of DXA scanning requires new experimental in vitro investigations, which, incidentally, also applies to the classical reference methods.

Validity of dual X-ray absorptiometry scanning for determination of body composition in IDDM patients

Data on body composition in patients with insulin-dependent diabetes mellitus (IDDM) are scarce. Dual X-ray absorptiometry (DXA) scanning has proved useful for this purpose in other groups of patients. We tested the validity of the DXA scanner for the determination of fat-free mass (FFM) and fat mass in IDDM patients and control subjects, as compared to other reference methods, i.e. total body potassium by 40K whole body counting (TBK), total body water by tritiated water (TBW), bioelectrical impedance analysis (BIA) and 24-h urinary creatinine excretion (Ucrea). A total of 13 healthy controls, 5 males and 8 females, aged 34.2 years +/- SD 10.4, and 11 IDDM patients, 5 males, 6 females, aged 28.1 years +/- 7.3, diabetes duration 4.2 +/- 2.9 (1.0-9.9), were examined. The patients had no long-term diabetic complications and they had normal ophthalmoscopy and urine albumin excretion. The agreement between FFM estimated by DXA and the other methods, expressed as mean difference +/- 2 SD was; for DXA vs. TBK, 0.09 +/- 6.26 and 0.50 +/- 5.26 kg for controls and IDDM patients respectively; DXA vs. TBW, -2.07 +/- 2.56 and -1.07 +/- 4.58 kg; DXA vs. Ucrea, -2.62 +/- 8.02 and 2.00 +/- 10.0 kg; DXA vs. BIA, -7.90 +/- 8.92 and -7.85 +/- 2.32 kg. The results obtained with BIA were significantly different from the other methods for both control subjects and IDDM patients. In conclusion, DXA scanning is a precise and valid method for estimation of fat-free mass in IDDM patients.

Massive weight loss restores 24-hour growth hormone release profiles and serum insulin-like growth factor-I levels in obese subjects

In the present study, we 1) determined whether the impaired spontaneous 24-h GH secretion as well as the blunted GH response to provocative testing in obese subjects are persistent disorders or transient defects reversed with weight loss and 2) investigated 24-h urinary GH excretion and basal levels of insulin-like growth factor-I (IGF-I), IGF-binding protein-3 (IGFBP-3), as well as insulin in obese subjects before and after a massive weight loss. We studied 18 obese subjects (age, 26 +/- 1 yr; body mass index, 40.9 +/- 1.1 kg/m2); 18 normal age-, and sex-matched control subjects; and 9 reduced weight obese subjects after a diet-induced average weight loss of 30.3 +/- 4.6 kg. Twenty-four-hour spontaneous GH secretion was estimated by obtaining 3240 integrated 20-min blood samples using a constant blood withdrawal technique and computerized algorithms. Body composition was determined using anthropometric measurements and dual energy x-ray absorptiometry scanning (DXA). In the obese subjects, 24-h spontaneous GH release profiles and the GH responses to insulin-induced hypoglycemia and L-arginine as well as basal IGF-I levels and the IGF-I/IGFBP-3 molar ratio were decreased, whereas insulin levels were elevated compared to those in normal subjects. In obese subjects, 24-h spontaneous GH secretion and serum IGF-I levels were inversely related to abdominal fat (r = -0.67; P < 0.01) and percent body fat (r = -0.69; P < 0.01), respectively. The decreased 24-h spontaneous GH release profiles, the decreased GH responses to insulin-induced hypoglycemia and L-arginine, the decreased basal IGF-I levels and IGF-I/IGFBP-3 molar ratio, as well as the elevated insulin levels were returned to normal after a massive weight loss in the obese subjects. In conclusion, the present study has shown reversible defects in 24-h spontaneous GH release profiles, basal IGF-I levels, and the IGF-I/IGFBP-3 molar ratio in obese subjects. The recovery of the 24-h GH release points to an acquired transient defect rather than a persistent preexisting disorder.

Body composition in hemodialysis patients measured by dual-energy X-ray absorptiometry

Dual-energy X-ray absorptiometry (DXA) measures three of the principal components of the body: fat mass, lean soft-tissue mass (comprising muscle, inner organs, and the body water), and the bone mineral content. The purpose of this study was to test the estimation capacity of DXA when it is applied to patients with end-stage renal failure. Twenty dialysis patients were examined by DXA before and after one hemodialysis session. A highly significant positive correlation between weight measurements performed by conventional scales and DXA was found. A positive correlation between fluid loss during dialysis and reduction in fat-free mass (lean soft-tissue mass plus bone mineral content) was observed by DXA. The estimation of the fat-free mass was independent of the amount of fluid loss. No significant differences in variance between the data obtained before and after the dialysis were observed. We conclude that DXA is a useful tool for estimating the magnitude of body compartments in patients with end-stage renal failure.

[Non-invasive measurement of body composition]

The concept of body composition covers the division of the body into a number of compartments. The most important are the fat mass (FM), the fat-free mass (FFM), the total body protein and the total body bone mineral content. Numerous methods for the measurement of body composition are available. The three classical methods for the measurement of FM and FFM, namely underwater weighing, measurement of total body potassium and measurement of total body water by isotope dilution, are often regarded as reference methods. However, newer methods such as computed tomography, neutron activation analysis and dual energy X-ray absorptiometry are increasingly used because of their reliability and ability for independent measurement of two or more components. Bioelectrical impedance analysis has become popular because of its clinical applicability. Three- or four-compartment models involving combination of two, three or more separate methods are more accurate than single methods, but are usually confined to research purposes because of the laborious measurement procedures. Computed tomography and dual energy X-ray absorptiometry have the unique possibility of regional measurements of body composition. Fat distribution and relative overweight may be estimated by simple anthropometric measures such as skinfold thicknesses. There are many applications for body composition measurements in research and clinical practice. These include treatment of obesity, growth hormone deficiency, diabetes mellitus and climacteric changes, as well as clinical nutrition and estimation of the hydration of dialysis patients and of critically ill intensive or surgical patients.

[No increase in the prevalence of vertebral fractures among postmenopausal women over a 10-year period]

We examined whether the prevalence of vertebral fracture in otherwise healthy, 70-year-old Danish women had increased over a period of ten years. The population-based, epidemiological study included two age-matched, representative samples of postmenopausal women. Group 1 (1979) consisted of 173 healthy women without secondary causes of osteoporosis, Group 2 (1989) of 387 women. X-rays of the thoraco-lumbar spine were assessed for vertebral fracture by five radiological methods. There was no significant difference between the two groups in the prevalence of vertebral fracture and the 95% confidence intervals overlapped completely in all methods. The prevalence rates varied by method from 35% to 80% but the distribution of fracture types was similar in the two groups. We conclude that the prevalence of vertebral fractures due to postmenopausal osteoporosis has not increased since 1979 in suburban Copenhagen, and that comparison of prevalences requires the same method of radiological assessment.

No secular increase in the prevalence of vertebral fractures due to postmenopausal osteoporosis

We examined whether the prevalence of vertebral fractures in otherwise healthy, 70-year-old Danish women had increased during an interval of 10 years. The population-based epidemiological study included two age-matched groups of postmenopausal women. Group 1 consisted of 70-year-old women (n = 386) living in a defined area of suburban Copenhagen recruited in 1979 for an epidemiological study. Of the 285 women who were entered, 173 were judged healthy, without secondary causes of osteoporosis. Group 2 was recruited by sending questionnaires to all women aged 68-72 years living in the same area in 1989. Of the 512 women who attended a medical screening, 387 were found to be without secondary causes of osteoporosis and had a spinal radiograph. Radiographs of the thoracolumbar spine were assessed for vertebral fracture by five radiological methods. There was no significant difference between the two groups in the prevalence of vertebral fractures and the 95% confidence intervals overlapped completely in all methods. The prevalence rates varied by method from about 35% to more than 80% but the distribution of fracture types was similar in the two groups. We conclude that the prevalence of vertebral fractures due to postmenopausal osteoporosis has not increased since 1979 in otherwise healthy women residing in suburban Copenhagen, and that comparison of prevalences between studies requires that they use the same method of radiological assessment.

Postmenopausal hormone replacement therapy prevents central distribution of body fat after menopause

The reduction in cardiovascular risk induced by hormone replacement therapy is only partly explained by changes in serum lipids and lipoproteins. As body composition and body fat distribution in particular are independent predictors of cardiovascular disease, we investigated the effect of postmenopausal hormone therapy on body composition parameters directly measured. Sixty-two early postmenopausal women were followed up for 2 years in a prospective, randomized, placebo-controlled study. We found that combined estrogen-progestogen therapy prevented the increase in abdominal fat after menopause (P less than .05), and that this effect was independent of the effect on serum lipids and lipoproteins. The therapy reduced postmenopausal bone loss significantly (P less than .001), whereas it did not have a statistically significant influence on total body fat mass or total lean body mass. The findings of the present study suggest that some of the protective impact of postmenopausal hormone therapy on cardiovascular disease may be explained by the effect on body composition, in particular abdominal fat.

The impact of measurement errors on the diagnostic value of bone mass measurements: theoretical considerations

It has become clear over the last decade that correlations between measurements of forearm bone mineral content (BMCarm) by single-photon absorptiometry (SPA) and measurements of spinal bone mineral density (BMDspine) by dual-photon absorptiometry (DPA) in healthy subjects and patients with spinal fractures are invariably significant, but not very powerful (i.e. r = 0.5-0.7). Nonetheless, several recent studies have shown that appendicular bone mass measurements discriminate between spinal fracture and non-fracture at least as well as do spinal DPA measurements. Correlations of a given parameter with measured BMDspine are less important than those with true BMDspine. To establish the latter we made the following assumptions: (1) accuracy errors or SPA BMCarm and DPA BMDspine measurements of 2%-4% and 8%-10%, respectively; and (2) a measured biological variation of SD = 14% for both BMCarm and BMDspine, corresponding to that of healthy women at the menopause. On these assumptions, we found that a correlation between true BMCarm and true BMDspine at about r = 0.8-0.9 yields a correlation between measured BMCarm and measured BMDspine at about r = 0.6--corresponding to experimental data in healthy women at the menopause. Furthermore, we found that the correlation between DPA measured BMDspine and true BMDspine is about the same as that between the SPA measured BMCarm and the true BMDspine. Thus, with the assumptions given above, spinal (DPA) and fore-arm (SPA) measurements appears to predict equally the true BMDspine in healthy perimenopausal women.

Validation of body composition by dual energy X-ray absorptiometry (DEXA)

The present study validates the use of dual energy X-ray absorptiometry (DEXA) for measurement of body composition. The precision error was expressed as the SD (CV%) for fat mass, FAT%, lean tissue mass, and total body bone mineral: 1.1 kg (6.4%), 1.6% (5.7%), 1.4 kg (3.1%), and 0.03 kg (1.2%), respectively. The accuracy study in vitro used (1) mixtures of water and alcohol, (2) mixtures of ox muscle and lard, and (3) dried bones. In the clinically relevant range of values there were only small influences on DEXA measurements of variations in amount and composition of the soft tissue equivalents. The accuracy study in vivo compared the components of body composition measured recently by DEXA and earlier by dual photon absorptiometry, counting of naturally occurring total body 40K, and body density by underwater weighing in 25 healthy adult subjects. We found agreement between fat percentage (and lean body mass) by DEXA and the three established measurements modalities; mean differences were (-5.3 to -0.4%) and (-0.7 to 2.5 kg) for fat percentage and lean body mass, respectively. We conclude that DEXA provides a new method of measuring body composition with precision and accuracy errors, which are compatible with the application of DEXA in group research studies and probably also in clinical measurements of the single subject.

Precision in assessment of osteoporosis from spine radiographs

Inter- and intra-observer variation in spine radiographs of 100 osteoporotic women and longitudinal change in roentgenologic status after 1 year of antiosteoporotic treatment were assessed. The method applied was naked eye inspection, and a score system estimating severity of fractures - vertebral deformation score (VDS). Agreement was assessed by the Kappa coefficient corrected for agreement by change. The results showed a satisfactory inter- and intraobserver agreement for wedge (Kappa = 0.72 and 0.90) and compression fractures (Kappa = 0.60 and 0.92). The method proved less reliable for endplate fractures (Kappa = 0.39 and 0.73). We think that the method of investigation is well suited for monitoring treatment effects in longitudinal studies.

Measurement of body fat in elderly subjects by dual-energy x-ray absorptiometry, bioelectrical impedance, and anthropometry

Body fat was measured in 46 elderly subjects by dual-energy x-ray absorptiometry [BF(DEXA)], bioelectrical impedance analysis (BIA), and anthropometry. Equations for prediction of the body fat (by DEXA) of elderly people by BIA and/or anthropometry were developed. The prediction of body fat (by DEXA) by anthropometric variables alone gave an r2 of 0.94 and the corresponding SEEs were 1.61 kg for men and 2.43 kg for women. When BIA variables were added as predictors, r2 increased by 2-5% (P less than 0.05) and the corresponding SEE decreased by 25% (P less than 0.05). The prediction of body fat (by DEXA) in elderly subjects and by BIA or anthropometry with equations developed in populations of young healthy adults (adapted from the literature) was generally not good although the correlation coefficients were high (r greater than 0.9, P less than 0.001), which suggests that our equations may improve prediction of body fat in elderly subjects.

Does a single local absorptiometric bone measurement indicate the overall skeletal status? Implications for osteoporosis and osteoarthritis of the hip

Regional bone mineral content (BMC) and density (BMD) (head, arms, chest, spine, pelvis, legs) of a total body dual photon 153Gd absorptiometry (DPA) scan were measured in 20 healthy postmenopausal women, 27 postmenopausal women with hip fracture, and 17 postmenopausal women with osteoarthritis of the hip. In addition, local BMC and BMD were measured in the proximal and distal regions of the distal forearm (BMCprox, BMDprox, BMCdist, BMDdist) by single photon absorptiometry (SPA); and in the lumbar spine (BMCL2-L4 and BMDL2-L4) by 153Gd DPA. The overall impression was a reduction of bone mass in hip fracture patients compared with healthy controls and an increase in the bone mass of osteoarthritic patients. These results were valid using both regional values of the total body scan, and local forearm and lumbar spine measurements, and statistically significant using one-way analysis of variance. There were, however, also significant within-group between-region differences (one-way analysis of variance), showing that the bone mass of the pelvis and legs in hip fracture patients was more reduced than in the remaining skeleton; in osteoarthritic patients it was not increased but rather unchanged or slightly reduced. The differences between the level of the three local measurements (BMDprox BMDdist BMDL2-L4), on the one hand, and the level of the six regional BMD values, on the other hand, were investigated by the two-way analysis of variance: local measurements = rows; regional values = columns. This analysis showed that none of the three local measurements was statistically better than the other two in predicting the overall level of skeletal bone mass as judged by the six regional values. We conclude that serious osteoporotic bone loss has a generalized nature, however, with a tendency towards lower values in the regions affected by fracture (viz: low bone mass in the legs of femoral neck fracture patients). Osteoarthritis may be associated with a high bone mass in most areas, but low values in the affected regions. Local lumbar spine measurement of bone mass by DPA is not superior to local forearm measurement of bone mass by SPA in predicting the nature of overall osteoporotic or osteoarthritic bone change.

Regional bone mineral in healthy and osteoporotic women: a cross-sectional study

Regional bone mineral content and density (BMC and BMD) was measured in six regions (head, arms, chest, spine, pelvis, and legs) using dual photon 153Gd absorptiometry (DPA) in 128 healthy women aged 21-77 years, and in 45 women presenting with Colles' fracture (mean age 65 years), 46 women with vertebral crush or wedge fracture (mean age 68 years), and 27 women with femoral neck-fracture (mean age 74 years). The age-related normal bone loss was generalized, uniformly distributed, and best described by a combination of a premenopausal linear and a postmenopausal exponential regression in all six regions. Looking at BMD, the overall expected bone loss from age 20 to age 80 was approximately 20% in all the regions. When the fracture patients were examined, we found also generalized bone deficit as the prominent feature, amounting to about 20% of the premenopausal level for Colles' and spinal fractures, and about 25% for femoral neck-fracture. However, there was a regional bias in the fracture patients, as the Colles' and spinal fracture patients had a preferential reduction in spinal and pelvic BMD, whereas the patients with femoral neck-fracture had a preferential reduction in pelvic and leg BMD. We conclude that age-related and osteoporotic bone loss is generalized. Furthermore, we propose that regional differences in osteoporotic bone loss are brought about by a simple biological variability of the range of (i) relative amount of trabecular and cortical bone, (ii) rate of loss in the two types of bone tissue, and (iii) time of onset of trabecular relative to cortical bone loss.

Total body bone mineral in light-for-gestational-age infants and appropriate-for-gestational-age infants

Dual-photon-absorptiometry using 153Gd in a whole body scanner was used to measure total body bone mineral in 51 newborn infants. In preterm light-for-gestational-age infants total body bone mineral was 12.6 g v.s. 25.6 g in preterm appropriate-for-gestational-age infants (p less than 0.05). In term light-for-gestational-age infants total body bone mineral was 41.4 g v. 84.2 g in term appropriate-for-gestational-age infants (p less than 0.001). The correlations between gestational age and total body bone mineral was best described by exponential regression lines.

Discriminative ability of total body bone-mineral measured by dual photon absorptiometry

We investigated the discriminative ability of total body bone-mineral expressed as the total body bone-density (TBBD) measured by dual photon absorptiometry (DPA) in 79 healthy premenopausal women, 27 healthy postmenopausal women, and 120 female osteoporotic fracture patients presenting with either Colles' fracture, vertebral fracture or femoral neck-fracture. TBBD was compared to the bone-mineral density of the lumbar spine (BMDspine) also measured by DPA, and to the bone-mineral content of the forearms (BMCforearm) measured by single photon absorptiometry (SPA). TBBD, BMDspine and BMCforearm showed that all the fracture patient groups had significantly reduced bone-mass. Using receiver operating characteristic (ROC) analysis, we found that TBBD had a tendency towards better discriminative ability than BMDspine or BMCforearm with regard to the discrimination between healthy premenopausal women and the three types of osteoporotic fractures (not significant in spinal fracture patients). BMCforearm had an intermediate position, whereas BMDspine had the smallest discriminative ability. TBBD also discriminated better between healthy postmenopausal women and hip-fracture patients than BMDspine or BMCforearm, whereas there was no significant difference between the three methods regarding the discrimination between the healthy postmenopausal women and the Colles' and spinal fracture patients. We conclude that the TBBD measurement by DPA has a discriminative potential which is better than the local spine or forearm measurements.

Lean body mass in small for gestational age and appropriate for gestational age infants

Dual photon absorptiometry using 153Gd in a whole-body scanner was used to measure lean body mass (LBM) in 51 newborn infants. LBM% decreased exponentially with increasing gestational age in both small for gestational age (SGA) and appropriate for gestational age (AGA) infants. In preterm SGA and AGA infants LBM was 104% and 103%, respectively, indicating that no fat was detectable. In term SGA infants LBM was 98%, which corresponded to 48 gm fat on average, and in term AGA infants LBM was 87%, which corresponded to 452 gm fat on average. The LBM%, ponderal index, and skinfold thickness were significantly different between AGA and SGA infants. Infants with clinical signs of intrauterine wastage had significantly higher LBM% than did infants without signs of weight loss. Our results on LBM% by dual photon absorptiometry agree with earlier dissection data; the clinically applicable methods of (1) height combined with weight (i.e., ponderal index), (2) skinfold thickness, and (3) scoring by clinical observations are useful for the estimation of lack of fat as an indicator of intrauterine growth retardation.

Accuracy of lumbar spine bone mineral content by dual photon absorptiometry

The accuracy of measurement of the bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2) of the lumbar spine by dual photon absorptiometry (DPA) was estimated by means of two different spine scanners (a Nuclear Data 2100 and a Lunar Radiation DP3). The lumbar spines of 13 cadavers were used. BMC and BMD were measured in situ and on the excised vertebrae in a solution of water/ethanol; and covered with ox muscle/porcine muscle/lard. The actual mineral weight and areal density were determined after chemical maceration, fat extraction, drying to a constant weight, ashing for 24 hr at 600 degrees C, and correction for the transverse processes. The true are was measured by parallax free X rays and planimetry. All measurements of BMC or BMD were highly interrelated (r = 0.94-0.99). The standard error of estimate (s.e.e.) of BMC in situ versus BMC in water/ethanol was 5.2%. The agreement between the BMD values of the two scanners was very good (s.e.e. = 2.9%). BMC in situ predicted the actual vertebral mineral mass with an s.e.e. of 8.1%. BMD in situ and BMD in water/ethanol predicted the actual area density with s.e.e.s of 10.3% and 5.0%, respectively. This study discloses the correlation and accuracy error of spinal DPA measurements in situ in whole cadavers versus the actual BMC and BMD. The error, which is underestimated in in vitro studies, amounts to 10%.

Total body bone mineral in healthy adults

Total body bone mineral (TBBM) was measured by dual photon absorptiometry (DPA) using a gadolinium 153 source in 135 healthy women aged 21 to 77 years and 101 healthy men aged 20 to 74 years. Among several predictor variables, including lean body mass measured by DPA, weight, and height, only normalization for the projected skeletal area (i.e., calculation of the total body bone density) had an appreciable effect on reduction of TBBM variation. In regression analysis of TBBM, raw and normalized, vs. age, a menopause-adjusted age was used for interpretation of data in women. Regardless of the normalization procedure, the best fit of TBBM vs. menopause-adjusted age was obtained by a polynomial regression of the third degree or a combined linear (premenopausal)--exponential (postmenopausal) regression. In men bone loss was linear with age (0.2% to 0.3% per year). In women, no significant premenopausal bone loss was found. The postmenopausal exponential loss was 4%, 0.44%, and 0.03% per year from TBBM 1 year, 10 years, and 20 years after the menopause. This amounts to a negative calcium balance of 100 mg calcium per day during the first postmenopausal year, and returning to zero after 20 years of menopause, when about 20% of premenopausal bone is lost.

Usefulness of regional bone measurements in patients with osteoporotic fractures of the spine and distal forearm

Bone mineral mass was measured in normal subjects and osteoporotic patients at two forearm sites (proximal and distal of the 8 mm site between the two forearm bones) by single photon absorptiometry and in the spine and whole body by dual photon absorptiometry. There were no signs of preferential low spinal bone mass in 28 patients with vertebral fractures. Their bone mass was at all sites 26% to 37% lower than the premenopausal mean value and 7% to 13% lower than in age-matched normal women. In 45 patients with forearm fractures bone reduction was also universal but only 3% to 6% lower than in healthy women of comparable age. The spinal bone mass in all the patients was significantly related to both forearm measurements with coefficients of correlation of 0.58-0.61 and s.e.e. of 18%. Compared to the premenopausal normal range the distal forearm site had a greater sensitivity in identifying patients with vertebral fractures than had the spinal measurement (chi-square test, p less than 0.01). We thus conclude that patients with vertebral fractures have universal osteoporosis and that measurement of spinal BMC had no predictive advantages over that of the forearm bone mass for population studies.

Bone composition in the distal forearm

Recent data have indicated that measurements of bone mass in the very distal part of the forearm is superior to more proximal measurements in identifying osteoporosis. Bone slices from the distal part of the forearm were obtained from 16 necropsies and the trabecular fraction of the total dry bone weight was measured in adjacent bone slices, 8 mm thick. Prior to autopsy bone mass at the corresponding sites was measured using a multipath single photon absorptiometric method by which scans are obtained proximal (proximal BMC) and distal (distal BMC) to the site, where the ulna and radius are 8 mm apart. The accuracy of bone measurements at the two sites was virtually similar (r = 0.98 and r = 0.94, respectively). In both areas the amount of trabecular bone increased towards the metaphysis with a trabecular/cortical ratio ranging from 10 to 60% (wt/wt). If bone composition is known it is possible to estimate rates of bone loss from the two compartments.

Bone mass, bone structure and vertebral fractures in osteoporotic patients

The clinical severity of bone disease was studied in 44 post-menopausal osteoporotic women. Spinal x-rays were assessed and compared to objective measurements of bone mass and bone structure; forearm bone mineral content (BMCarm) by single photon absorptiometry, total body bone mineral content (TBBM), and spinal bone mineral content (BMCspine) by dual photon absorptiometry, and corrected cortical width (C Cor W), trabecular bone volume (TBV), and indices of trabecular microstructure by iliac crest biopsy. For comparison data of BMCarm, TBBM and BMCspine in 25 post-menopausal normals are shown. The results showed a reduction in amount of both cortical and trabecular bone in the fracture patients compared to normals. A subdivision of the fracture patients into two groups constituting 26 patients with wedge fractures alone and 18 patients with compression (+wedge) fractures showed that the latter group had a further predominantly trabecular bone loss and a further deteriorated trabecular microstructure. On an individual basis no agreement between clinical severity of bone disease and amount and structure of bone could be demonstrated.

The diagnostic validity of local and total bone mineral measurements in postmenopausal osteoporosis and osteoarthritis

Assessment of different forms of prevention and treatment of bone mineral loss depends upon valid and precise methods to assess bone mass. We have here studied four groups of women: 45 healthy premenopausal women, 37 healthy postmenopausal women, 21 women with osteoarthritis and 20 with hip fractures. Bone mass was measured in the spine and total body by dual photon absorptiometry and in two forearm sites (proximal and distal bone mineral content (BMC) by single photon absorptiometry. The long-term (1 year) reproducibility was 1.2% for proximal BMC, 1.6% for distal BMC, 5.5% for spinal BMC, and 2.1% for total body bone mass (TBBM). In the early postmenopausal years bone mass was mainly reduced in areas with a high content of trabecular bone. In elderly postmenopausal women and women with hip fractures bone mass was almost identical in all four sites studied. The osteoarthritic patients had an 18% reduction of bone mass in the forearms and in TBBM, whereas the spinal bone mass was only reduced by 6%. In all subgroups TBBM could be predicted from the forearm measurements with standard errors of estimates of 9-13%. When the osteoarthritic women were excluded spinal bone mass could be predicted from both forearm measurements with a standard error of 15% (r = 0.74). The distal forearm BMC seems to be a more accurate estimate of spinal bone mass than does the proximal measurement. Of the 20 patients with hip fracture 16 had a distal forearm value below the premenopausal normal range, whereas spinal bone mass was subnormal in only eight (P less than 0.05). We conclude that bone loss is universal in patients with hip fracture and measurements of forearm bone mass will meet most clinical and research demands.

Prediction of body composition by age, height, weight, and skinfold thickness in normal adults

In order to establish an easy and reliable method for estimating body composition, the lean body mass (LBM) and the fat mass (FM) were measured in vivo in 228 normal adults (130 women and 98 men) using dual photon (153Gd) absorptiometry. In addition, skinfold thickness was measured at two sites in each subject. Multiple regression equations of LBM and FM based on age, height, and weight were computed (r = .86 to .95, SEE = 2.1 to 2.9 kg). These correlations were only slightly improved in men, but not in women, when the results of the skinfold measurements were included in the calculations. We conclude that LBM and FM can be estimated in normal adults from age, height, and weight with a predictive error below 3 kg.

Bone turnover in healthy adults measured by whole body retention and urinary excretion of 99mTc-MDP. Normalization by bone mass

Whole body retention (WBR) and urinary excretion (UE) of 99mTc-diphosphonate, two complementary methods of measuring the total bone turnover, were performed in 161 normal subjects, 82 women and 79 men, aged 20-70 years. Both WBR and UE were a function of age in the women, whereas there were no age-dependent differences in the men. Between the women and men in identical age groups, the differences did not reach significance. Total body bone mineral (TBBM) was measured by dual photon absorptiometry (DPA) in all subjects. This was done in order to obtain expressions for bone turnover per bone mass as a function of age and sex. This correction emphasized the general picture seen in the raw WBR and UE data: bone turnover was constant in the men throughout life and in the women before the menopause, and only moderate differences were found between the sexes before the age of 50. After this age the mean female values increased sharply. It is noteworthy that none of the postmenopausal subjects showed low turnover values. Our data clearly demonstrate that an increase in bone turnover is part of the pathophysiology of the well-known bone loss in postmenopausal women.

Is postmenopausal bone loss an age-related phenomenon?

Forearm bone mineral content (BMC), an index of skeletal mineralization, and lean body mass (LBM), an index of the muscle mass in the body, were calculated in 574 healthy, white subjects, aged 20-89 years. In women, there was no significant change in BMC with age until the menopause. Thereafter, a significant decline averaging 15% per decade was found up to the age of 70 years, after which it was 10% per decade. In men, there was a significant overall decline of about 4% per decade from the age of 20. When BMC was corrected for LBM, the age-related fall in men disappeared, while remaining without a significant trend in premenopausal women. This was, however, not the case in women after the menopause, where a significant decline of about 12% per decade was noted. These data clearly demonstrate that the major contribution to the well-known bone loss in postmenopausal women is not a simple age-related phenomenon. The development of osteoporosis must be due to some additional bone-diminishing effect on the female skeleton, most likely the absence of estrogen.

Iliac crest biopsy: an investigation on certain aspects of precision and accuracy

We investigated the intraobserver and section to section variation in static and dynamic histomorphometric variables in ten iliac crest biopsies. We also did a comparative study of iliac crest and lumbar spine specimens from 14 cadavers. The ten patients had osteoporosis (spinal crush fractures) and the 14 specimens taken at the necropsies were either normal or osteopenic, without malignant bone disease, bone metastases or metabolic bone disease. The majority of the coefficients of variation (CV%) were between 5 and 15% in the intraobserver analysis and 10 and 30% in the section to section analysis. These results suggest that more sections from each biopsy should be investigated to increase the precision. The correlation of variables from the iliac crest and spine showed poor agreement between resorption and osteoid variables. This fact, combined with a rather low precision of bone dynamic variables in the section to section investigation, raises the question of whether iliac crest biopsy is representative for trabecular bone turnover in the skeleton.

Representativity of regional to total bone mineral in healthy subjects and 'anticonvulsive treated' epileptic patients. Measurements by single and dual photon absorptiometry

Dual photon (153Gd) and single photon (125I) absorptiometry were used to measure the regional bone mineral content (BMC) and density (BMD), as well as the total body mineral content (TBBM) and density (TBBD), in sixty-nine healthy subjects and in twenty-three epileptics on phenobarbitone. The BMCs (and BMDs) of all regions were significantly correlated to each other and to the TBBM (and TBBD). No difference in the ability to discriminate between the different study groups was found for the various regions, excepting the BMD of the head. The relationship between the forearm BMC and TBBM was highly significant, and identical in the five groups. The relationships between spinal BMC and forearm BMC, and TBBM differed in the five groups. It is concluded that some local measurement may be used as estimates of the total body bone mineral in some groups of patients with minor metabolic bone disease and healthy subjects.

Bone changes occurring spontaneously and caused by estrogen in early postmenopausal women: a local or generalised phenomenon?

Regional values of bone mineral content and bone mineral density were calculated from total body dual photon absorptiometry scans of 52 early postmenopausal women treated with oestrogen for one year and of 52 similar women treated with placebo. The six regions were head, arms, chest, spine, pelvis, and legs. In addition, bone mineral density of the lumbar spine was measured by dual photon absorptiometry and bone mineral content of the forearm by single photon absorptiometry, using separate special purpose scanners. All regions were unchanged after one year of treatment with oestrogen, excluding the lumbar spine, for which values rose. Values for all regions except the lumbar spine fell significantly in the placebo group. The rates of loss ranged from 2% to 8%, with no significant differences among the regions. It is concluded that loss of bone in the early menopause is a generalised phenomenon, affecting all parts of the skeleton. Furthermore, oestrogen prophylaxis for loss of bone is effective in all parts of the skeleton. Finally, it is suggested that the measurement of bone mineral content in the forearm should be used for clinical follow up of bone changes, as this method is superior to others in the ratio of change to precision.

Total and local bone mineral during estrogen treatment: a placebo controlled trial

103 healthy postmenopausal women with a natural menopause 0.5-2 years previously were randomized to either estrogen (n = 52) or placebo (n = 51) treatment. Total body bone mineral (TBBM) was measured by dual photon absorptiometry and forearm bone mineral content (BMC) by single photon absorptiometry before and after one year. Both TBBM and forearm BMC fell significantly (P less than 0.001) in the placebo group, but were unchanged after estrogen treatment. The loss of bone mineral in the placebo group during one year was 5% (TBBM) and 3% (forearm BMC). A significant correlation (r = 0.53; P less than 0.001) was found between the fractional percent change in forearm BMC and TBBM. It is concluded, that both the forearm BMC and the TBBM measurements are suitable for following changes in bone mass postmenopausally. The almost equal relative amount of cortical bone in the total skeleton and in the forearm BMC may explain that longitudinally performed forearm BMC measurements are indicative of average changes in the total skeletal status.

Total and local bone mass before and after normalization for indices of bone and body size

Both single and dual photon absorptiometry are excellent techniques for longitudinal studies, owing to their high precision. Because of large biological variations they are less suited for diagnosing bone disease in single subjects. In a homogeneous group of 161 women, bone mass in the distal forearm, spine, and whole body measured by photon absorptiometry was significantly related to various general indices of body size (r = 0.29-0.59). Normalization procedures for variations of these variables could only reduce the individual variation by 10-20%. Local indices of body size (i.e. bone width or scan area) were no better in the forearm or spine. Normalization for the projected skeletal area of the whole body could reduce the SD of the total body bone mineral (TBBM) from 322 to 126 grams (15-6%). This might imply that the normalized TBBM can be used for diagnostic purposes.

Measurement of lean body mass and total body fat using dual photon absorptiometry

We describe a method for measuring the lean body mass (LBM) and total body fat (FAT) by dual photon absorptiometry (DPA). A total body rectilinear scan was employed with a radiation source of 1 Ci 153Gd. The reliability of estimating the lean percent was assessed in vitro using limb phantoms consisting of ox muscle, lard, and human bone. The precision and accuracy in vitro of the lean percent determination were 1.5% and 1.9%, respectively. The accuracy error in vivo of measuring the total mass of soft tissues (TMST) was approximately 1.4%, thus yielding an overall accuracy error of the LBM of about 2.5%. The precision in vivo of the lean percent and the LBM in kg of duplicate measurements on five healthy subjects was 2.5% and 2.2%, respectively. Other estimates of the LBM and FAT, ie, the calculation according to Boddy et al6 and the skinfold thickness measurement (triceps and subscapular), were compared to the DPA measurement in 100 healthy subjects. High correlations were found between the FAT or FAT% by DPA versus (1) the FAT or FAT% calculated according to the formulae of Boddy et al, and (2) the skinfold thickness. The correlations between the FAT and FAT% by Boddy et al and the skinfold thickness were, however, moderate. The correlation between LBM by DPA and LBM by Boddy et al was highly significant (r = 0.96, SEE = 4.4%). We conclude that LBM and FAT measurements using DPA have precision and accuracy errors that are commensurate with a reliable estimation of the gross body composition.(ABSTRACT TRUNCATED AT 250 WORDS)

Iliac crest biopsy: representativity for the amount of mineralized bone

The aim of the study was to evaluate the representativity of iliac crest biopsy for the amount of mineralized trabecular and cortical bone in the skeleton. The following data were obtained on bone from 14 necropsies: right sided iliac crest biopsy, lumbar spine biopsy, dry fat free weight of lumbar spine, bone mineral density (BMD) in the lumbar spine and dry fat free weight of cortical and trabecular bone from the left distal forearm. The amount of mineralized cortical and trabecular bone from various sites was compared by linear regression analysis. The results confirm iliac crest biopsy as a good predictor of the amount of trabecular bone, but not of cortical bone. Furthermore, iliac crest biopsy is a better estimate of the amount of trabecular bone in the lumbar spine than spinal BMD.

Comparison of single- and dual-photon absorptiometry in postmenopausal bone mineral loss

We describe a single photon absorptiometric (SPA) technique, which enables differential estimation of the rates of loss from trabecular and cortical bone. Ten scans are obtained in the forearm: six in an area with about 7% trabecular bone and four scans in the adjacent distal area with a trabecular bone content of 25%. By comparing bone masses of these two sites in 19 postmenopausal and 53 premenopausal women, the postmenopausal trabecular bone loss was estimated to be approximately seven times greater than cortical loss within the first years of cessation of regular vaginal bleeding. On a group basis the bone loss at the distal forearm scan site (by SPA) corresponded closely to the spinal bone loss (by dual-photon absorptiometry). The reproducibility of the two scan sites in the forearm was 1-1.5% (CV%), which makes the method suitable for longitudinal studies. Corrections for variations in fatty tissue covering can be made without deterioration of the reproducibility. The high precision can only be achieved with a good calibration procedure; if calibration is not done the reproducibility error increases two- or threefold.

Are disease duration and degree of functional impairment determinants of bone loss in rheumatoid arthritis?

One hundred and five patients with rheumatoid arthritis treated with a variety of antirheumatic drugs, excepting glucocorticoids, were stratified according to the degree of functional impairment (functional classes I to IV) and duration of the disease (0-3 years; 4-8 years; and greater than 8 years). The variables investigated were distal forearm bone mineral content (BMC), biochemical markers of bone formation: serum alkaline phosphatase and serum bone gamma-carboxyglutamic acid containing protein (BGP) and biochemical markers of bone resorption: fasting urinary calcium and fasting urinary hydroxyproline. Significant relationships were found between BMC and functional impairment and duration of the disease. Indices of bone formation and bone resorption rose with increasing functional impairment, particularly those of bone resorption. It is concluded that disability induces osteopenia in rheumatoid arthritis by increasing the bone turnover with a more marked increased in resorption than in the formation processes. The effect of the disease duration is merely that of adding more years of functional impairment.