Biomedical subjects

B Oldroyd

Publications and source records attributed to B Oldroyd.

At least 19 recordsLinked to original sources

PubMed2005

Pediatric in vivo cross-calibration between the GE Lunar Prodigy and DPX-L bone densitometers.

Dual energy x-ray absorptiometry (DXA) machine cross-calibration is an important consideration when upgrading from old to new technology. In a recent cross-calibration study using adult subjects, close agreement between GE Lunar DPX-L and GE Lunar Prodigy scanners was reported. The aim of this work was to cross-calibrate the two machines for bone and body composition parameters for pediatrics from age 5 years onwards. One-hundred ten healthy volunteers aged 5-20 years had total body and lumbar spine densitometry performed on DPX-L and Prodigy densitometers. Cross-calibration was achieved using linear regression and Bland-Altman analysis. There was close agreement between the machines, with r2 ranging from 0.85 to 0.99 for bone and body composition parameters. Paired t-tests demonstrated significant differences between machines that were dependent on scan acquisition mode, with the greatest differences reported for the smallest children. At the lumbar spine, Prodigy bone mineral density (BMD) values were on average 1.6% higher compared with DPX-L. For the total body, there were no significant differences in BMD; however, there were significant differences in bone mineral content (BMC) and bone area. For small children, the Prodigy measured lower BMC (9.4%) and bone area (5.8%), whereas for larger children the Prodigy measured both higher BMC (3.1%) and bone area (3.0%). A similar contrasting pattern was also observed for the body composition parameters. Prodigy values for lean body mass were higher (3.0%) for small children and lower (0.5%) for larger children, while fat body mass was lower (16.4%) for small children and higher (2.0%) for large children. Cross-calibration coefficients ranged from 0.84 to 1.12 and were significantly different from 1 (p<0.0001) for BMC and bone area. Bland-Altman plots showed that within the same scan acquisition modes, the magnitude of the difference increased with body weight. The results from this study suggest that the differences between machines are mainly due to differences in bone detection algorithms and that they vary with body weight and scan mode. In general, for population studies the differences are not clinically significant. However, for individual children being measured longitudinally, cross-over scanning may be required.

Absorptiometry, Photon↗

PubMed2004

Effect of oral bisphosphonates on bone mineral density and body composition in adult patients with cystic fibrosis: a pilot study.

BACKGROUND: Approximately two thirds of adult patients with cystic fibrosis have reduced bone mineral density and up to one quarter have osteoporosis at one or more sites. Any bone mineral deficits are likely to be exacerbated in patients following lung transplantation by their immunosuppressive regimen. Vertebral collapse and rib fractures will impair the ability to cough and the efficacy of physiotherapy treatments. METHODS: Patients attending the Leeds Regional Adult Cystic Fibrosis Unit with either osteopenia or osteoporosis on dual energy x ray absorptiometry (DXA) scanning were offered treatment with oral bisphosphonates after exclusion of abnormal vitamin D, calcium, or phosphate levels, abnormal thyroid function, or hypogonadism. Those declining treatment or patients with a normal initial DXA scan formed the control group. A second DXA scan was performed after a mean of 2.4 years in the treatment group and 2.9 years in the non-treatment group. Patients in the active group were asked to complete a short questionnaire detailing their adherence to treatment. RESULTS: The medians of the differences in annual changes in bone parameters between treatment and control groups showed significant differences in bone mineralisation in favour of the treatment group at the lumbar spine (L2-L4), the femoral neck, and for total body measurements. There were no significant differences in weight, height, or body composition in either patient group. Most treated patients stated that they adhered to treatment most of the time. CONCLUSION: Treatment with oral bisphosphonates may improve bone mineralisation in adult patients with cystic fibrosis. The results of this pilot study need to be further explored in a randomised controlled trial.

Absorptiometry, Photon↗

PubMed2003

Bone density, body composition and menstrual history of sedentary female former gymnasts, aged 20-32 years.

Few studies have examined the effects of retirement from sports involving regular, high impact and weight bearing activity on bone mass. This cross-sectional study compared total body and regional areal bone mineral density (aBMD, g/cm(2)) within female former gymnasts and women who had never participated in structured sport or exercise, and explored relations between aBMD of these former gymnasts and their duration of retirement. Eighteen sedentary female former gymnasts (GYM) and 18 sedentary controls (CON) were recruited. GYM displayed a broad range of duration of retirement (3-12 years) and a wide age range (20-32 years). GYM and CON were paired individually to match for age, body mass and stature. GYM had commenced training at least 3 years pre-menarche and had trained post-menarche for 2 or more years. They had trained continuously for 5-12 years and had retired between age 14 and 22 years. Measurements of aBMD and body composition were made using dual energy X-ray absorptiometry (DXA). Group mean values of physical and skeletal characteristics were compared using paired t-tests. Linear regression was used to explore possible relations of aBMD within GYM to duration of retirement. GYM displayed a higher aBMD than CON at all measurement sites, which ranged in magnitude from 6% for the total body ( P=0.004), to 11% for the total femur ( P=0.006). Elevations of aBMD within GYM equated to T-scores ranging from +0.8 (arms) to +1.7 (legs). There were no differences in body composition or age of menarche between groups, although 11 of 18 GYM reported a history of irregular menses. There was no significant decline of aBMD with increasing duration of retirement in GYM. The results suggested that an elevated bone mass in female former gymnasts was retained during early adulthood, in spite of a cessation of training for up to 12 years.

Adult↗

PubMed2003

Cross-calibration of GE/Lunar pencil and fan-beam dual energy densitometers--bone mineral density and body composition studies.

OBJECTIVE: In vitro and in vivo comparisons of bone mineral density (BMD) and body composition between GE/Lunar pencil (DPXL) and fan-beam (PRODIGY) absorptiometers. DESIGN: Comparison of BMD, bone mineral content (BMC) and area of lumbar spine (L2-L4), femoral neck and total body. Total body composition compartments tissue (TBTissue), fat (TBF), lean tissue (TBLean) and %TBF were also compared. SETTING: Centre for Bone and Body Composition Research, University of Leeds. PHANTOMS/SUBJECTS: A range of spine phantoms, a variable composition phantom (VCP) and total body phantom. A total of 72 subjects were included for the in vivo study. RESULTS: In vitro: A small significant underestimation of BMD by the Prodigy compared to the DPXL ranging from 0.7 to 2% (p<0.05-0.001) for the spine phantoms. The Prodigy underestimated the VCP %Fat. Although the Prodigy underestimated phantom TBBMD by 1.1+/-1.0%, TBBMC and area were reduced by 8.2+/-1.4 and 7.3+/-1.0%, respectively. The Prodigy overestimated TBTissue 1508 g (2.2%), TBLean 588 g (1.2%), TBF 919 g (4.8%) and %TBF (0.8%). In vivo: BMD cross-calibration was only required in the femoral neck, DPXL(BMD)=0.08+0.906*PRODIGY(BMD). The Prodigy had higher estimates for TBTissue 1360 g (2.3%), TBLean 840 g (2.0%), TBF 519 g (3.4%), TBBMC 32.8 g (1.3%) and %TBF (0.3%). Cross-calibration equations were required for TBTissue(DPXL)=-1158+0.997*TBTissue(PRODIGY) and TBBMC(DPXL)= 89.7+0.949*TBBMC(PRODIGY). CONCLUSIONS: Small differences between the two absorptiometers for both BMD and body composition can be made compatible by use of cross-calibration equations and factors. The discrepancy in body composition compartments requires further research.

Absorptiometry, Photon↗

PubMed2003

Estimates of percentage body fat in young adolescents: a comparison of dual-energy X-ray absorptiometry and air displacement plethysmography.

OBJECTIVE: To evaluate the accuracy of percentage body fat (%fat) estimates from air displacement plethysmography (ADP) against an increasingly recognised criterion method, dual-energy X-ray absorptiometry (DXA), in young adolescents. DESIGN: Cross-sectional evaluation. SETTING: Leeds General Infirmary, Centre for Bone and Body Composition Research, Leeds, UK. SUBJECTS: In all, 28 adolescents (12 males and 16 females), age (mean+/-s.d.) 14.9+/-0.5 y, body mass index 21.2+/-2.9 kg/m(2) and body fat (DXA) 24.2+/-10.2% were assessed. RESULTS: ADP estimates of %fat were highly correlated with those of DXA in both male and female subjects (r=0.84-0.95, all P<0.001; s.e.e.=3.42-3.89%). Mean %fat estimated by ADP using the Siri (1961) equation (ADP(Siri)) produced a nonsignificant overestimation in males (0.67%), and a nonsignificant underestimation in females (1.26%). Mean %fat estimated by ADP using the Lohman (1986) equations (ADP(Loh)) produced a nonsignificant underestimation in males (0.90%) and a significant underestimation in females (3.29%; P<0.01). Agreement between ADP and DXA methods was examined using the total error (TE) and methods of Bland and Altman (1986). Males produced a smaller TE (ADP(Siri) 3.28%; ADP(Loh) 3.49%) than females (ADP(Siri) 3.81%; ADP(Loh) 4.98%). The 95% limits of agreement were relatively similar for all %fat estimates, ranging from +/-6.57 to +/-7.58%. Residual plot analyses, of the individual differences between ADP and DXA, revealed a significant bias associated with increased %fat (DXA), only in girls (P<0.01). CONCLUSIONS: We conclude that ADP, at present, has unacceptably high limits of agreement compared to a criterion DXA measure. The ease of use, suitability for various populations and cost of ADP warrant further investigation of this method to establish biological variables that may influence the validity of body fat estimates.

Absorptiometry, Photon↗

PubMed2003

Comparison of body composition methods in overweight and obese children.

The objective of the present study was to investigate the accuracy of percent body fat (%fat) estimates from dual-energy X-ray absorptiometry, air-displacement plethysmography (ADP), and total body water (TBW) against a criterion four-compartment (4C) model in overweight and obese children. A volunteer sample of 30 children (18 male and 12 female), age of (mean +/- SD) 14.10 +/- 1.83 yr, body mass index of 31.6 +/- 5.5 kg/m, and %fat (4C model) of 41.2 +/- 8.2%, was assessed. Body density measurements were converted to %fat estimates by using the general equation of Siri (ADPSiri) (Siri WE. Techniques for Measuring Body Composition. 1961) and the age- and gender-specific constants of Lohman (ADPLoh) (Lohman TG. Exercise and Sport Sciences Reviews. 1986). TBW measurements were converted to %fat estimates by assuming that water accounts for 73% of fat-free mass (TBW73) and by utilizing the age- and gender-specific water contents of Lohman (TBWLoh). All estimates of %fat were highly correlated with those of the 4C model (r > or = 0.95, P < 0.001; SE < or = 2.14). For %fat, the total error and mean difference +/- 95% limits of agreement compared with the 4C model were 2.50, 1.8 +/- 3.5 (ADPSiri); 1.82, -0.04 +/- 3.6 (ADPLoh); 2.86, -2.0 +/- 4.1 (TBW73); 1.90, -0.3 +/- 3.8 (TBWLoh); and 2.74, 1.9 +/- 4.0 DXA (dual-energy X-ray absorptiometry), respectively. In conclusion, in overweight and obese children, ADPLoh and TBWLoh were the most accurate methods of measuring %fat compared with a 4C model. However, all methods under consideration produced similar limits of agreement.

Absorptiometry, Photon↗

PubMed2003

Differences in bone density, body composition, physical activity, and diet between child gymnasts and untrained children 7-8 years of age.

Strategies that enhance the acquisition of bone mass may be protective against osteoporosis. BMD was compared in 20 artistic gymnasts (10 boys; 10 girls) and 20 untrained children ages 7-8 years. Higher regional values of BMD were observed in female gymnasts than untrained girls. If retained to adulthood, this higher BMD may protect skeletal integrity in later life. Strategies that enhance the acquisition of bone mass in children may assist with the prevention of osteoporosis. This study explored the effects of regular high-impact and weight-bearing activity before the age of 7 years on total and regional bone mineral density (BMD). Twenty artistic gymnasts (10 boys and 10 girls) and 20 untrained children, 7-8 years of age, were recruited. The untrained children were matched to gymnasts by sex, height, weight, and age. Female gymnasts trained 8-10 h per week and had trained regularly for 3-4 years. Male gymnasts trained 4-6 h per week and had trained for 1-2 years. Measurements of bone mineral density were made using DXA for total body BMD (TBBMD); lumbar spine, both areal (aSBMD) and volumetric (vSBMD); total spine; pelvis; arms; and legs. Significant mean differences (8-10%) in aSBMD, vSBMD, arm BMD, and TBBMD were observed between female gymnasts and untrained girls (p < 0.05: aSBMD, vSBMD, and TBBMD body mass (BM); p < 0.01: arm BMD). A nonsignificant trend toward a higher TBBMD/BM and arm BMD was observed in male gymnasts compared with untrained boys. Trends toward a higher BMD within the pelvis, legs, and total spine were also observed in gymnasts. There were no differences in total and regional BMD between untrained boys and untrained girls. The results suggest that gymnastics training before the age of 7 years enhances the acquisition of bone mass at selected skeletal sites. The magnitude of this enhancement seems to be linked to the cumulative volume of such training. If retained during adolescence and young adulthood, a surfeit of bone acquired through high-impact and weight-bearing activity in early childhood may protect skeletal integrity in later life.

Body Composition↗

PubMed2001

The measurement of total body potassium in patients on peritoneal dialysis.

OBJECTIVES: To assess the validity of measuring total body potassium (TBK) to estimate fat-free mass (FFM) and body cell mass (BCM) in patients on peritoneal dialysis (PD). METHODS: We studied 29 patients on PD (14 men, 15 women) and 30 controls (15 men, 15 women). We calculated TBK by using a whole-body counter to measure 1.46 MeV gamma-ray emissions from naturally occurring 40K. We measured total body water (TBW) by deuterium oxide dilution, and extracellular water (ECW) from bromide dilution. These measurements allowed us to estimate intracellular water (ICW), fat-free mass dilution (FFM(Dilution)), and body cell mass dilution (BCM(Dilution)). RESULTS: The FFM(TBK) in male PD patients (55.7 +/- 7.0 kg) did not differ from that in male controls (57.0 +/- 10.9 kg). The FFM(TBK) in female PD patients (38.4 +/- 6.8 kg) was less than that in female controls (44.7 +/- 4.5, p < 0.01). The FFM(Dilution) did not differ from the FFM(TBK). Correlation of FFM(TBK) and FFM(Dilution) was r = 0.90, p < 0.0001 for all subjects; r = 0.90, p < 0.0001 for PD patients; and r = 0.90, p < 0.0001 for controls. Bland-Altman comparison of FFM(Dilution) with FFM(TBK) in individuals showed bias 0.6 kg, range -8.5 kg to 9.7 kg for the whole group; bias 1.4 kg, range -7.9 kg to 10.7 kg for PD patients; and bias -0.2 kg, range -9.0 kg to 8.6 kg for controls. The BCM(TBK) in male PD patients (30.1 +/- 4.5 kg) did not differ from that in male controls (31.9 +/- 6.2 kg). The BCM(TBK) in female PD patients (19.0 +/- 4.4 kg) was less than that in female controls (23.1 +/- 2.9 kg, p < 0.01). The BCM(Dilution) results did not differ from those for the BCM(TBK). Correlation of BCM(TBK) and BCM(Dilution) was r = 0.90, p < 0.0001 for all subjects; r = 0.87, p < 0.0001 for PD patients; and r = 0.93, p < 0.0001 for controls. Bland-Altman comparison of BCM(Dilution) with BCM(TBK) in individuals showed bias 0.1 kg, range -5.9 kg to 6.1 kg for the whole group; bias 0.0 kg, range -6.9 kg to 6.9 kg for PD patients; and bias 0.1 kg, range -5.0 kg to 5.2 kg for controls. The [K+]ICW did not differ between PD patients and controls (148.0 +/- 25.1 mmol/L vs 148.1 +/- 14.3 mmol/L, p = nonsignificant). CONCLUSIONS: Total body potassium is a valid, noninvasive technique for measuring FFM and BCM in PD patients. In our PD patient group, depletion of FFM and BCM as compared with controls was identified in the women but not in the men.

Body Composition↗

PubMed2000

Effect of peritoneal fluid on whole body and segmental multiple frequency bioelectrical impedance in patients on peritoneal dialysis.

OBJECTIVE: We investigated the ability of whole body and segmental multiple frequency bioelectrical impedance (MFBIA) to detect peritoneal fluid in peritoneal dialysis patients. DESIGN: Prospective study. SETTING: Teaching hospital renal unit. SUBJECTS: Patients on regular peritoneal dialysis. INTERVENTIONS: Whole body and segmental MFBIA measurements before and after drainage of peritoneal fluid. RESULTS: Changes estimated by MFBIA in total body water (-0.4 (0.8) litres) and extracellular water (-0.3 (0.3) litres) were much lower than the actual changes (2.0 (0.4) litres), P<0.0001. Derived resistances Recf and Ricf increased significantly for the trunk but not for total body measurements and changes did not correlate with volumes of fluid drained. CONCLUSIONS: MFBIA is limited in its ability to detect intraperitoneal fluid, using both whole body and segmental techniques.

Adult↗

PubMed2000

Standardized limb abduction for bioimpedance measurements using position restraints.

Bioelectrical impedance analysis (BIA) measurements are widely used in the assessment of body hydration. However, there are many variables which can influence the impedance values obtained and their individual significance is not entirely clear. One such variable is limb position and it is possible to standardize this either by invoking subject cooperation or by the use of some form of mechanical constraint. This study evaluates these two approaches. BIA measurements were made on five healthy male volunteers both with the positioners and without. Additional variables including room temperature, prandial status, exercise, alcohol intake, bed surface for the test, and bladder status were controlled. The mean percentage difference between impedance values with and without positioners was (-0.37 +/- 0.69)%. The mean difference between occasions with and without mechanical fixing was (2.02 +/- 2.5)% and (2.58 +/- 3)% respectively. None of these differences is statistically significant. It was concluded that reproducibility of BIA measurements obtained with active subject cooperation in limb position is not significantly improved if mechanical positioners are used. This may not apply where subject cooperation is poor e.g. in very sick or very young people or in repeated measurements in different days.

Adult↗

PubMed2000

Effects of icodextrin in automated peritoneal dialysis on blood pressure and bioelectrical impedance analysis.

BACKGROUND: Glucose absorption from glucose-based dialysis fluids limits ultrafiltration from the daytime dwell in automated peritoneal dialysis (APD). Icodextrin may allow greater ultrafiltration during the daytime period in APD, enhancing fluid control. METHODS: A 7.5% icodextrin dialysate was compared with a 2. 27% glucose dialysate for the daytime dwell in 14 subjects on APD. Blood pressure, weight and body water compartments estimated by multifrequency bioelectrical impedance (MFBIA) were determined in subjects using 2.27% glucose as the daytime dwell and then repeated 1 month after switching to icodextrin. RESULTS: Icodextrin resulted in symptomatic hypotension requiring reduction of antihypertensive medication in six of the 14 patients. Despite this reduction in treatment, systolic blood pressure fell from 142.4 (23.9) mmHg to 122.9 (17.7) mmHg, P<0.005, and diastolic blood pressure tended to fall from 82.8 (9.8) mmHg to 76.8 (10.1) mmHg, P=0.075. Change in systolic blood pressure significantly correlated with changes in weight (r=0.62, P<0.05) and MFBIA estimates of total body water (TBW) (r=0.56, P<0.05), extracellular water (ECW) (r=0.79, P<0.002), extra/intracellular water ratio (ECW/ICW) (r=0.72, P<0.01) and derived resistances R(ecf) of ECW (r=-0.69, P<0.01) and R(inf) of TBW (r=-0.66, P<0.02). Changes in diastolic blood pressure significantly correlated with changes in ECW (r=0.64, P<0.02) and ECW/ICW ratio (r=0.58, P<0.05), and almost significantly with R(ecf) (r=-0.51, P=0.08) and R(inf) (r=-0.52, P=0.07) estimated by MFBIA, but not with changes in weight or TBW. CONCLUSIONS: Use of icodextrin for the daytime dwell in APD results in improved fluid balance and blood pressure control compared with 2.27% glucose. MFBIA detected clinically important changes in fluid content in these patients.

Adult↗

PubMed2000

Osteoporosis and osteopenia in adults and adolescents with cystic fibrosis: prevalence and associated factors.

BACKGROUND: Patients with cystic fibrosis (CF) have many risk factors for reduced bone mineral density (BMD). The aim of this study was to determine the prevalence of osteoporosis and osteopenia in a large cross section of patients and to identify risk factors. METHODS: All patients attending the regional centre were invited to participate in the study. Bone mineral density was measured at the lumbar spine, femoral neck, and for total body with a Lunar DPX-L densitometer. Multiple indices of disease severity were investigated, and liver and thyroid function, blood calcium, phosphate, 25-OH vitamin D, follicle stimulating and luteinising hormone, oestradiol, and testosterone levels were measured. Patients completed a four day prospective dietary diary. Exercise was assessed by a seven day activity recall questionnaire. Sexual development and treatment histories were obtained. The relationship between all these variables and BMD measurements was analysed. RESULTS: Sixty six percent of 114 patients assessed had osteopenia or osteoporosis. The Shwachman-Kulczycki (SK) clinical score (higher score = less severe disease) correlated significantly with BMD at the lumbar spine and femoral neck, and with total body BMD (p<0.001). There was a predicted increase of 0.0032 g/cm(2) in lumbar spine BMD for every unit increase in the SK score. Oral steroid use was significantly associated with reduced BMD at the lumbar spine (p = 0.017) and femoral neck (p = 0.027). CONCLUSIONS: Osteopenia and osteoporosis are common findings in a heterogeneous population of adults with CF. Patients at most risk are those with severe disease and those who have used corticosteroids.

Adolescent↗

PubMed1999

Limited ileal resection in infancy: the long-term consequences.

BACKGROUND/PURPOSE: The longer-term sequelae of short bowel syndrome in infancy are reasonably well documented, but little is known about the long-term nutritional and metabolic effects of limited (less than 50 cm) ileal resection. This makes it difficult to formulate a rational follow-up policy in such children. METHODS: All children who underwent limited ileal resection for either necrotizing enterocolitis (NEC) or intussusception at our institution between 1984 and 1992 were invited to attend a detailed clinical, anthropometric, hematologic, and biochemical assessment, together with a biliary and renal ultrasound scan and measurement of bone mineral density. RESULTS: Twenty-four children (NEC, 17; intussusception, 7) of median age 7.4 years (range, 5.5 to 13.7 years) agreed to participate. Nine previously had undergone an isolated ileal resection, and 15 also had had variable lengths of colon removed. The length of resected ileum ranged from 3 to 44 cm, with a median of 10 cm. Seven control subjects in whom neonatal NEC developed but recovered without surgery were also evaluated. Median height, weight, and body mass index after ileal resection were between the 25th and 50th percentiles; no child was stunted or wasted. After ileal resection, one boy was found to have asymptomatic vitamin B12 deficiency, and three children had low plasma concentrations of vitamin A. Hematologic and biochemical parameters were otherwise normal apart from a few marginally low trace element levels in both subjects and controls. No renal calculi were detected, and bone mineral density measurements were normal in all except one child. Four children had cholelithiasis, all of whom had previously undergone limited ileal resection for NEC (two isolated, two ileocolic). Thus, the prevalence of cholelithasis after limited ileal resection for NEC was 24% at a median age of 7.0 years. CONCLUSIONS: Growth and nutritional status are well preserved after limited ileal resection in infancy. Limited ileal resection for NEC is associated with a subsequent high prevalence of cholelithiasis and a risk of vitamin B12 deficiency. These findings are important when planning strategies for long-term follow-up.

Bone Density↗

PubMed1999

Comparison of icodextrin and glucose solutions for the daytime dwell in automated peritoneal dialysis.

BACKGROUND: The sustained ultrafiltration achieved by icodextrin is more suited for the daytime dwell in automated peritoneal dialysis (APD) than glucose solutions. METHODS: Seventeen patients receiving APD underwent assessment using three different solutions for the daytime dwell: 2.27% glucose, 3.86% glucose and 7.5% icodextrin. Patients were then observed on icodextrin for a 6 month period. RESULTS: Daytime ultrafiltration was greater for 3.86% glucose (median 0.10, IQR 0.01 to 0.321) P<0.01 and icodextrin (median 0.26, IQR 0.14 to 0.361) P<0.001 than 2.27% glucose (median -0.19, IQR -0.54 to -0.081), with 3.86% glucose and icodextrin not being significantly different. Positive ultrafiltration occurred in 3/17 patients with 2.27% glucose, 13/17 patients with 3.86% glucose and 16/17 patients with icodextrin (chi2 P<0.0001). The difference in ultrafiltration of icodextrin and 3.86% glucose correlated with the 4 h dialysate/plasma creatinine ratio in a PET test (r = 0.51, P<0.05). Daytime Kt/V urea was greater for 3.86% glucose (median 0.27, IQR 0.20 to 0.48 per week, P<0.01) and icodextrin (median 0.31, IQR 0.27 to 0.49 per week, P<0.0001) than for 2.27% glucose (median 0.22, IQR 0.15 to 0.38 per week), with the difference between 3.86% glucose and icodextrin not reaching statistical significance (P = 0.06). Daytime creatinine clearance was greater for 3.86% glucose (median 10.2, IQR 6.9 to 13.61/week/1.73 m2, P<0.02) and icodextrin (median 12.1, IQR 9.3 to 15.71/week/1.73 m2, P<0.005) than for 2.27% glucose (median 8.8, IQR 4.9 to 11.91/week/1.73 m2). Daytime creatinine clearance was greater for icodextrin than for 3.86% glucose (P<0.005). The effects of icodextrin were sustained for the 6 month observation period. CONCLUSIONS: Icodextrin produced enhanced ultrafiltration and clearances compared with 2.27% glucose, without the exposure of the peritoneum to hypertonic glucose solutions.

Adult↗

PubMed1999

Regional bone mineral density after orthotopic liver transplantation.

OBJECTIVES: Although there is a fall in lumbar spine bone mineral density (BMD) after liver transplantation, little is known about femoral neck or total body BMD. Therefore we determined: (a) the proportion of patients with preexisting hepatic osteopenia before transplantation and (b) the effects of transplantation on global and regional BMD. DESIGN: Retrospective analysis of BMD measurements of patients before and up to 2 years after liver transplantation. METHODS: BMD was assessed by dual energy X-ray absorptiometry in 56 patients, before and at regular intervals after liver transplantation, for up to 24 months, to measure total body, lumbar spine (L2-L4) and femoral neck BMDs. RESULTS: Pre-transplant, 23% of patients had osteoporosis (a negative Z score > 2). Paired data before and after transplantation revealed no change in total body BMD. However, there was a fall in lumbar spine BMD (1.04+/-0.03 to 1.02+/-0.03 g/cm2; P < 0.04) at 1 month after transplantation. The reduction in lumbar spine BMD was seen up to 12 months, BMD at 18-24 months being similar to pre-transplant values. Femoral neck BMD also fell (0.96+/-0.06 to 0.83+/-0.04 g/cm2; P < 0.03), but only after 6-9 months, thereafter remaining below pre-transplant values until the end of the follow-up period. CONCLUSIONS: Although osteopenia is common in patients with liver disease, total bone density does not fall after transplantation. Nonetheless regional lumbar spine and femoral neck bone density does fall after transplantation with a risk period for femoral neck fracture which may extend for up to 2 years.

Absorptiometry, Photon↗

PubMed1998

Comparison of in-vivo body composition using two Lunar dual-energy X-ray absorptiometers.

OBJECTIVE: To compare in-vivo composition analysis between two dual energy X-ray absorptiometers, a DPX and a DPX/L, from the same manufacturer (LUNAR), pre(Study A) and post(Study B) hardware changes on both absorptiometers. DESIGN: Comparison of (1) quality assurance (QA) data: air-counts low (38 keV), air-counts high (70 keV), air-counts ratio, percent spillover, R-delrin; and (2) total body compartments: total body tissue (TBTISS), total body fat (TBF), percent total body fat (%TBF), total body lean (TBLEAN), total body bone mineral content (TBBMC) and total body bone mineral density (TBBMD), between the two absorptiometers. SETTING: Centre for Bone and Body Composition Research, University of Leeds. SUBJECTS: Study A, 14 normal subjects and Study B, a different cohort of 19 normal subjects, were scanned on both machines on the same day. RESULTS: In Study A, large significant differences were observed in the QA parameters between the two machines. The DPX, air-counts low and air-counts high, being 25% and 22% lower than the DPX/L. The Bland Altman method of analysis indicated that the DPX was significantly higher for TBTISS (0.3 kg), %TBF (2%) and TBF ( 1.4 kg) and correspondingly lower for TBLEAN (-1.0 kg). No significant difference was observed in TBBMC. After the hardware changes (Study B) a marked reduction in the differences in QA air-counts was observed. The DPX air-counts low was now 1% higher and air-counts high 8% lower than the DPX/L. The DPX had now only small significant negative differences for %TBF (-0.6%) and TBF (-0.4 kg) and a small significant positive difference for TBLEAN (0.4 kg), compared to the DPX/L. TBBMC difference although slightly increased, was still non-significant. CONCLUSIONS: The closer agreement observed in the QA parameters after the hardware changes was associated with a reduction in the mean differences, 95%CI of the mean differences and limits of agreement of the comparison of body composition analysis from the Lunar machines using the Bland-Altman method. The study indicates that the QA limits set for bone mineral analysis may require more stringent limits for body composition.

Absorptiometry, Photon↗

PubMed1998

Effects of orthotopic liver transplantation on body composition.

AIMS/BACKGROUND: The effects of orthotopic liver transplantation on body composition are unclear. We aimed to assess changes in body composition after transplantation using dual energy x-ray absorptiometry and total body potassium. METHODS: Dual energy x-ray absorptiometry and total body potassium counting to assess muscle mass were performed in 55 patients before and up to 24 months after liver transplantation and the results expressed as paired data before and at time intervals after transplantation. RESULTS: The results showed that total body weight fell by 3.6 +/- 1.3 kg (p < 0.02) at 1 month, with a maximal fall in lean tissue mass at 2-5 months of 4.8 +/- 1.2 kg (p < 0.003). Thereafter, no change in lean tissue mass was recorded, although there were increases at 12 and 24 months of total body weight (11.5 +/- 2.4 kg, 7.8 +/- 3.1 kg; p < 0.03, respectively) and fat mass (12.9 +/- 2.2 and 10.5 +/- 2.7 kg; p < 0.003). A fall in total body potassium was seen at 1 month (118 +/- 12 mmol; p < 0.003) and 2-5 months (176 +/- 9.9 mmol; p < 0.03), which mirrored the fall in lean mass. CONCLUSIONS: After liver transplantation there is an initial fall in body weight due to a loss of lean mass. Lean mass does not recover after transplantation, although there is an increase in fat mass that leads to the observed increase in total body weight.

Absorptiometry, Photon↗

PubMed1997

Increased plasma leptin/fat ratio in patients with chronic renal failure: a cause of malnutrition?

BACKGROUND: Protein-energy malnutrition occurs in patients with chronic renal failure primarily due to loss of appetite. The ob gene protein, leptin, which is secreted by adipocytes, regulates body composition by lowering food intake. We have measured plasma leptin in undialysed and dialysed patients and in controls and the concentrations have been related to body composition, dietary intake, and biochemistry. METHODS: Plasma leptin was measured by radioimmunoassay in 93 individuals in groups of undialysed, peritoneal dialysed, and haemodialysed patients and controls. Body composition was determined by DEXA. RESULTS: Protein-energy malnutrition was evident in non-dialysed and dialysed patients from low lean or fat tissues, plasma albumin and transferrin. A third of the dialysis patients were eating less than prescribed intakes. Leptin relative to total fat mass (ng/ml/kg) was significantly greater for patients than for controls, particularly the dialysed patients. Leptin was highly correlated with total, arm, leg, and all other fat measurements, e.g. r for leptin vsm % total fat was: undialysed 0.88, PD 0.81, HD 0.93, and controls 0.83 (P < 0.0001 for all). Dialysis patients with the highest leptin/fat mass ratio had low protein intakes and significantly lower lean tissue mass. Leptin/fat ratio correlated inversely with dietary intake e.g. with protein intake in g/day and marginally in g/kg of ideal weight/day. Leptin concentration was unrelated to plasma creatinine or residual renal function or to the protein 'nutritional indices', albumin and transferrin. CONCLUSIONS: Our data suggests that leptin is markedly increased in some patients with chronic renal failure. The association of increased leptin with low protein intake and loss of lean tissue is consistent with leptin contributing to malnutrition but a definitive role cannot be substantiated by this study.

Aged↗