Quantitative ultrasound in the assessment of skeletal status in uremic patients

Fragility fractures and osteoporosis in CKD: pathophysiology and diagnostic methods

Both chronic kidney disease (CKD) and osteoporosis are major public health problems associated with an aging population. Osteoporosis is characterized by reduced bone mineral density, while CKD results in qualitative changes in bone structure; both conditions increase the predisposition to fragility fractures. There is a significant coprevalence of osteoporotic fractures and CKD, particularly in the elderly population. Not only is the risk of fracture higher in the CKD population, but clinical outcomes are significantly worse, with substantial health care costs. Management of osteoporosis in the CKD population is particularly complex given the impact of renal osteodystrophy on bone quality and the limited safety and hard outcome data for current therapy in patients with severe CKD or on dialysis therapy. In this review, we discuss the pathophysiology of osteoporosis, the impact of CKD on bone strength, and the role of novel imaging techniques and biomarkers in predicting underlying renal osteodystrophy on bone histomorphometry in the context of CKD.

A two-yr prospective study of bone health in children after renal transplantation employing two imaging techniques

The aim of this study was to prospectively and longitudinally evaluate bone properties with the use of two bone imaging techniques (dual energy X-ray absorptiometry [DXA], and quantitative ultraSonography [QUS]) in pediatric renal transplant recipients. Fourteen patients (eight boys and six girls) with a mean age of 12.25 ± 3.11 yr (range: 8-17.5 yr) completed a two-yr follow-up. Measurements of bone mineral density (BMD) by DXA at lumbar spine and hip and speed of sound (SOS) by QUS at radius and tibia were performed at the beginning and at the end of the study. A significant improvement in mean Z-score of SOS values measured at tibia (1.01 ± 1.31 vs. -0.46 ± 1.14, p = 0.005) was observed. On the contrary, mean Z-score of BMD values measured at femoral neck was significantly reduced (-1.95 ± 2.15 vs. -0.33 ± 1.13, p = 0.041). Finally, multivariate stepwise regression analyses showed that glomerular filtration rate at the beginning of the study was the best predictor of the difference in BMD Z-scores measured at lumbar spine. Additionally, values of intact parathormone (iPTH) at the beginning of the study and the change in iPTH throughout the study predicted the 72.3% of the difference in Z-score of SOS measured at radius with an inverse relationship.

Phalangeal quantitative ultrasound measurements in chronic hemodialysis patients: a 4-year follow-up

In the course of chronic kidney disease, bone metabolism disturbances occur and become aggravated simultaneously with the progression of renal disorder, worsening patients' quality of life. We conducted a 4-year follow-up to assess phalangeal quantitative ultrasound (QUS) measurements in 32 patients undergoing chronic hemodialysis (17 males and 15 females) whose mean ages were 56.3 ± 15.2 years. The QUSs of hand phalanges were performed using DBM 1200 (IGEA, Carpi, Italy) and are expressed as amplitude-dependent speed of sound (Ad-SoS), Z-scores, and T-scores. In comparison with the age-, sex-, and body mass index-adjusted control group, QUS parameters were significantly decreased in all patients undergoing dialysis. During the 4-year follow-up, Ad-SoS and T-scores in all study groups sloped significantly with time. The significant negative relationships between follow-up Ad-SoS results and both baseline and follow-up parathormone values were demonstrated. Our results confirm a high prevalence of bone disturbances in patients undergoing chronic hemodialysis, and they do not improve during renal replacement therapy. The parathormone level seems to be an important agent in influencing bone status, but further studies are needed to understand the other risk factors in kidney-related bone disease.

Comparative study of quantitative ultrasonography and dual-energy X-ray absorptiometry for evaluating renal osteodystrophy in children with chronic kidney disease

Our aim was to assess bone parameters in children with chronic kidney disease (CKD) with both dual-energy X-ray absorptiometry (DXA) and quantitative ultrasonography (QUS) and additionally with biochemical markers of bone turnover. Twenty children (12 boys and 8 girls) with CKD and a mean decimal age of 9.47 ± 4.44 years were included in the study where anthropometric parameters (height and weight), pubertal status, bone mineral density (BMD) at lumbar spine, speed of sound (SOS) measured by QUS at radius and at tibia, and biochemical markers of bone metabolism were measured. Six patients (30%) had tibial SOS Z score <-1, and 52.7% had radial SOS Z score <-1, whereas only 16.67% had BMD Z score <-1. Patients had significantly increased levels of serum intact parathormone (p < 0.001), serum bone alkaline phosphatase (BAP) (p < 0.001) and serum N-terminal-mid fragment (aminoacids 1-43) of osteocalcin (p < 0.001) compared to controls, whereas serum osteoprotegerin was significantly decreased in patients compared to controls (p = 0.001). SOS was significantly correlated to BAP (r = -0.586, p = 0.013 and r = -0.709, p = 0.001, respectively, for radius and tibia). In conclusion no association between DXA and QUS measurements was documented in our study, whereas QUS was better correlated to biochemical indices of ROD.

Quantitative ultrasound in osteoporosis and bone metabolism pathologies

Quantitative ultrasound (QUS) has been introduced in the medical field for the study of bone tissue to identify changes in the tissue that could suggest the presence of osteoporosis and bone fragility. The ultrasound technique is simple, versatile, and its low cost and lack of ionizing radiation have led to the diffusion of this method worldwide. The present article is an overview of the most relevant developments in the field of quantitative ultrasound, in clinical and experimental settings. The advantages and limitations of the present technique and suggestions for its use in the clinical practice are reported.

Management of osteoporosis in CKD Stages 3 to 5

Osteoporosis and chronic kidney disease (CKD) are both common conditions of older adults and both may be associated with substantial morbidity. However, biochemical and histologic changes that occur with progressive kidney disease require specific interventions, some of which may be concordant with osteoporosis management in the general population, whereas others may be less relevant or perhaps even harmful. In this article, we review the diagnosis of and management strategies for osteoporosis in individuals with CKD, placing these into perspective with the recently published KDIGO (Kidney Disease: Improving Global Outcomes) guidelines for treatment of CKD-mineral and bone disorder (CKD-MBD). Specifically, we highlight osteoporosis treatment recommendations by CKD stage and discuss new avenues for osteoporosis treatment that may be useful in individuals with CKD.

Quantitative ultrasound of the calcaneus in hemodialysis patients

The aim of this study was to investigate the bone status of hemodialysis patients and identify factors that have influence on bone quality. Four hundred eighty-nine subjects (213 males and 276 females) on maintenance hemodialysis and 696 healthy subjects (309 men, 387 women) were enrolled in this study. Speed of sound (SOS), broadband ultrasound attenuation (BUA) and quantitative ultrasound index (QUI) were assessed by quantitative ultrasound (QUS) at the right calcaneus in both groups. Serum levels of intact parathyroid (iPTH), total alkaline phosphatase (ALP), calcium and phosphate were measured to determine their influence on bone status in hemodialysis patients. All QUS parameters were significantly lower in hemodialysis patients than in controls (p < 0.0001). Stepwise multiple linear regression analysis in male patients indicated that age, weight, calcium-phosphate product and ALP were significant predictors of QUS parameters (adjusted R(2) = 0.15 in SOS; adjusted R(2) = 0.17 in BUA and QUI). In female patients, same findings including number of parity were observed in SOS only (adjusted R(2) = 0.25 in SOS). In postmenopausal patients, the duration of menopause was significant negatively correlated with all QUS parameters (p < 0.01). In conclusion, patients on maintenance hemodialysis had additional risk of bone loss. Advanced age, low body weight, high calcium-phosphate product and high ALP level were important risk factors for deterioration of bone quality.

Genetic architecture of hand quantitative ultrasound measures: a population-based study in a Sardinian genetic isolate

It is now recognized that quantitative ultrasound (QUS) measures may predict osteoporotic fracture risk independently of bone mineral density. Although many studies have examined genetic and environmental components of bone mineral density and calcaneal QUS measures, few of them were addressed to phalangeal QUS phenotypes, and none to graphic trace parameters. This study aims to evaluate the relative contribution of genetics in the expression of phalangeal QUS traits in the adult healthy population of a Sardinian genetic isolate. Our sample includes 6056 men and women aged 30-103 years, from 43 extended pedigrees recruited in 10 villages of Ogliastra region in occasion of a large epidemiologic survey. Amplitude-dependent speed of sound (AD-SoS), fast wave amplitude (FWA), signal dynamic (SDy), bone transmission time (BTT) and ultrasound bone profile index (UBPI) were obtained from the non-dominant hand using the IGEA DBM Sonic Bone Profiler. These phenotypes were first regressed on age, anthropometric and bioimpedance measures, serum calcium, phosphorus and alkaline phosphatase, alcohol and caffeine consumption, smoking status, exercise and also months since menopause and estrogens use in women. Adjusted QUS parameters were then analyzed by univariate and bivariate variance component models to obtain heritability estimates and genetic and environmental correlations. QUS parameters were correlated to age, anthropometric and bioimpedance measures, serum phosphorus, alkaline phosphatase and to reproductive history and menopause in women. All phenotypes demonstrated substantial heritabilities ranging from 0.29+/-0.03 for SDy to 0.55+/-0.03 for FWA. Proportion of variance due to all covariates ranged from 36% for SDy to 59% for BTT. Many significant genetic and environmental correlations were found between the different QUS measures. In this study, genetic factors appear to play a relevant role in determining hand QUS measures even when taking into account various important environmental factors. Furthermore, the modest genetic correlations may imply the existence of partially unique sets of genes affecting different QUS traits, thus suggesting that QUS parameters measure different properties of bone tissue.

Vitamin D receptor gene, biochemical bone markers and bone mineral density in Mexican women on dialysis

BACKGROUND

The influence of the Bsm1 polymorphism of the vitamin D receptor (VDR) gene on mineral and bone disorders in chronic kidney disease (CKD) is still under discussion. The aim of this study was to analyse the relationship between VDR polymorphism, bone mineral density (BMD), biochemical bone markers and clinical factors in women on peritoneal dialysis (PD) and haemodialysis (HD).

METHODS

In a cross-sectional study, 197 women (42 +/- 10 years; 25% with diabetes mellitus (DM); body mass index (BMI) 25.26 +/- 4.77 kg/m(2)) treated by PD (72%) or HD (28%) underwent measurements of BMD (measured at the calcaneus by quantitative ultrasound; expressed as T- and Z-scores) and plasma total calcium (tCa), intact parathyroid hormone 1-84 (iPTH), phosphorus, albumin, glucose, osteoprotegerin (OPG), fetuin-A, intact osteocalcin-49 and N-MID fragment 1-43 aa (N-MID osteocalcin) N-terminal propeptide of type 1 procollagen (PINP) and C-terminal telopeptide-beta aspartic acid (BCL). DNA was extracted from peripheral blood. PCR products were digested with Bsm1 to analyse VDR polymorphism.

RESULTS

The Z-score of BMD was -1.1 +/- 1.03. According to the values of osteopenia (T-score = -1.0), patients with higher BMD were younger, had lower frequency of amenorrhoea and diabetes and had higher serum creatinine and fetuin levels as well as lower levels of PINP. In a stepwise multivariate logistics analysis, osteopenia was associated with presence of genotype BB+Bb (OR = 3.26, P < or = 0.003) and age (OR = 0.95, P = 0.050). According to the B allele, bb: n = 126 (64%) and BB+Bb: n = 71(36%), group bb had significantly higher mean Z-scores (-0.97 +/- 1.0 vs -1.3+/-0.92; P < or = 0.021).

CONCLUSIONS

The high frequency of osteopenia observed in female CKD patients on dialysis is associated with age and genetic predisposition as revealed by its association to the Bsm1 VDR polymorphism.

Osteoprotegerin and Bone Mineral Density in Hemodiafiltration Patients

A newly identified cytokine, osteoprotegerin (OPG) appears to be involved in the regulation of bone remodeling. In vitro studies suggest that OPG, a soluble member of the TNF receptor family of proteins, inhibits osteoclastogenesis by interrupting the intercellular signaling between osteoblastic stromal cells and osteoclast progenitors. As patients with chronic renal failure (CRF) often have renal osteodystrophy (ROD), we investigated the role of osteoprotegerin (OPG) in ROD, and investigated whether there was any relationship between serum OPG, intact parathyroid (PTH) (iPTH), vitamin D, and trabecular bone. Serum OPG combined with iPTH might be a useful tool in the noninvasive diagnosis of ROD, at least in cases in which the range of PTH values compromises reliable diagnosis. Thirty-six patients on maintenance hemodiafiltration (HDF) and a control group of 36 age and sex matched healthy subjects with no known metabolic bone disease were studied. The following assays were made on serum: iPTH, osteocalcin (BGP), bone alkaline phosphatase, 25(OH)-cholecalciferol, calcium, phosphate, OPG, IGF-1, estradiol, and free testosterone. Serum Ca++, P, B-ALP, BGP, IGF-1, iPTH, and OPG levels were significantly higher in HDF patients than in controls, while DXA measurements and quantitative ultrasound (QUS) parameters were significantly lower. On grouping patients according to their mean OPG levels, we observed significantly lower serum IGF-1, vitamin D3 concentrations, and lumbar spine and hip bone mineral density in the high OPG groups. No correlation was found between OPG and bone turnover markers, whereas a negative correlation was found between serum OPG and IGF-1 levels (r=-0.64, p=0.032). Serum iPTH concentrations were positively correlated with bone alkaline phosphatase (B-ALP) (r=0.69, p=0.038) and BGP (r=0.92, p<0.001). The findings made suggest that an increase in OPG levels may be a compensatory response to elevated bone loss. The low bone mineral density (BMD) levels found in the high OPG group might have been due to the significant decrease in serum IGF-1 and vitamin D3 observed. In conclusion, the findings made in the present study demonstrate that increased OPG in hemodiafiltration patients is only partly due to decreased renal clearance. As it may partly reflect a compensatory response to increased bone loss, this parameter might be helpful in the identification of patients with a marked reduction in trabecular BMD.

Quantitative ultrasound in the assessment of skeletal status

Quantitative ultrasound (QUS) is a non-invasive technique for the investigation of bone tissue in several pathologies and clinical conditions, especially in the field of osteoporosis. The versatility of the technique, its low cost and lack of ionising radiation have led to the diffusion of this method worldwide. Several studies have been conducted in the last years to investigate the potential of QUS in multiple areas with promising results; the technique has been applied in the prediction of osteoporotic fractures, in monitoring therapies, in the investigation of secondary osteoporosis, in paediatrics, neonatology and genetics. Our review article gives an overview of the most relevant developments in the field of quantitative ultrasound, both in clinical and in experimental settings.

Quantitative ultrasound of phalanges of adults with end-stage renal disease or who have undergone renal transplantation

In patients with end-stage renal disease (ESRD), bone disturbances are common. The aim of this study was to compare the bone mineral status in patients with ESRD, in patients post renal transplantation and in healthy controls. The groups were composed of 218 males and 126 females (ESRD), 43 males and 23 females (renal transplantation) and 614 males and 927 females (healthy controls). Skeletal status was evaluated by quantitative ultrasound measurements of the phalanges using a DBM 1200 (IGEA, Carpi, Italy), which measures the amplitude-dependent speed of sound (Ad-SoS) in m/s. Data analyses were performed with Statistica 6 for Windows (StatSoft, Inc., Tulsa, OK, USA). The Z-scores in gender subgroups were significantly lower in patients undergoing dialysis and after transplantation than in controls (p<0.00001). The Z-scores did not differ between gender subgroups after transplantation and the Z-scores of dialyzed males were significantly better than in females (p<0.00001). The mean value of Z-scores in patients after transplantation was significantly lower than in all patients with ESRD (p<0.05) and in males (p<0.01). The duration of dialysis negatively influenced the Ad-SoS; however, the time elapsed since transplantation did not. The cumulative corticosteroid dose did not correlate with skeletal variables. In conclusion, patients with ESRD treated with hemodialysis and postrenal transplantation patients, across both genders, were observed to have skeletal disturbances.

Quantitative ultrasound measurements in diabetic and nondiabetic patients with end-stage renal disease

The aim of the study was to assess skeletal status in diabetic and nondiabetic subjects with end-stage renal disease (ESRD). One hundred twenty-three patients with ESRD (57 patients with diabetes: 9 type 1 and 48 type 2) and 66 nondiabetic patients were evaluated. Control group comprised 1541 subjects (614 males and 927 females). Diabetes and/or renal insufficiency was the only reason of bone disease and, in control group, no factors known to influence bone metabolism (chronic diseases or prolonged medications) were noted. Skeletal status was evaluated by quantitative ultrasound measurements at the hand phalanges using DBM 1200 (IGEA, Carpi, Italy), which measures amplitude-dependent speed of sound (Ad-SoS [m/s]). Because of some differences in mean age in subgroups of patients and controls, comparisons were performed using values of Z-score. In all diabetic patients, Z-score was significantly higher compared with nondiabetics (p < 0.05). In all type 1 diabetes patients, Z-score was significantly lower than in all nondiabetic patients (p < 0.05) and in patients with type 2 diabetes (p < 0.001). Z-score was also significantly lower in type 2 diabetics than in nondiabetic females (p < 0.00001) but did not differ in males. Comparisons between Z-scores in controls and patients showed that Z-score in nondiabetic females was significantly lower than in female controls (p < 0.000001), and in nondiabetic males--diabetic type 2 males as well as females--Z-score did not differ vs. results in adequate control group. Z-score was significantly lower in patients with diabetes type 1 vs. all controls (p < 0.001). Correlation analysis showed in all nondiabetic patients that Z-score was negatively affected by duration time of dialysis (r = -0.37, p < 0.01) and parathyroid hormone (PTH) serum level (r = -0.35, p < 0.01). In patients with type 1 diabetes, only PTH influenced significantly Z-score (r = -0.76, p < 0.05) and, in patients with type 2 diabetes, no significant correlations were obtained. Subjects with type 1 diabetes seemed to be sensitive for skeletal disturbances in a course of renal insufficiency, whereas subjects with type 2 diabetes did not show such skeletal pathology as shown by ultrasound measurements at hand phalanges.

Quantitative ultrasound technique at the phalanges in discriminating between uremic and osteoporotic patients

This study was conducted to test the ability of quantitative ultrasound technique (QUS) at the phalanges to discriminate between uremic and osteoporotic patients. Three groups of subjects (38 dialytic women, 16 osteoporotic women with vertebral fractures, 19 non-dialytic and non-fractured women) were recruited at the Department of Radiology at "Casa Sollievo della Sofferenza" Hospital, San Giovanni Rotondo, Italy. The groups were matched for age and body mass index (BMI). On all subjects the following measurements were performed: spinal BMD by QCT and by DXA, Femoral BMD by DXA, phalangeal QUS. For QUS measurements, the DBM Sonic (IGEA, Carpi, Italy) was applied to the metaphysis of the proximal phalanges of the last four fingers of the hand. Osteoporotic women with vertebral fractures showed significantly lower values of spinal BMD by QCT and DXA and Ward's Triangle BMD with respect to hemodialytic patients (p<0.005). All QUS values, except for BTT and SoS, showed lower values in osteoporotic women with respect to hemodialytic patients (p<0.05). Control group showed higher values of AD-SoS, BTT and SoS than hemodialytic patients (p<0.005) while the two groups did not differ for BMD values measured with both QCT and DXA. UBPI and FWA data showed a similar behaviour to DXA and QCT results, whereas BTT and SoS showed a completely different behaviour. AD-SoS was the only parameter that could effectively discriminate among the three groups (ANOVA, p<0.0001). We conclude that phalangeal QUS can discriminate between hemodialysed patients and controls with similar bone mineral density, and can also discriminate between hemodialysed and osteoporotic subjects with vertebral fractures. Different characteristics of ultrasound signal can be ascribed to each bone tissue condition, enabling a clear differentiation of bone tissue changes occurring in menopause, osteoporosis and renal osteodystrophy.

Quantitative ultrasound in monitoring of skeletal status in adults with end-stage renal disease

The aim of the longitudinal study was to assess skeletal status in 29 subjects (18 males and 11 females) with end-stage renal disease (ESRD) being on regular hemodialysis. Control group consisted of 494 healthy subjects (305 males and 189 females). Skeletal status was evaluated by quantitative ultrasound measurements at the hand phalanges using DBM Sonic 1200 (IGEA, Carpi, Italy), which measures amplitude-dependent speed of sound (Ad-SoS, in m/s), performed three times: at the baseline, six and 12 months later. A precision expressed in root mean square-CV% was 0.72% in males and 0.43% in females. The values of Ad-SoS, T-score and Z-score at the baseline were significantly lower than in controls (p < 0.05). The mean values of Ad-SoS decreased over a period of observation; in the whole group from 1979 +/- 106 m/s to 1928 +/- 105 m/s, p < 0.0001, in males from 2003 +/- 93 m/s to 1949 +/- 111 m/s, p < 0.001 and in females from 1940 +/- 121 m/s to 1894 +/- 108 m/s, p < 0.05. Ad-SoS Z-scores dropped significantly over a period of the study in whole group (-1.14 +/- 1.64 to -2.08 +/- 2.26, p < 0.01), in males (-0.63 +/- 1.44 to -1.74 +/- 2.29, p < 0.0001) and in females nonsignificant decrease was observed. Using the least significant change (LSC) values for skeletal measurement, a decrease in Ad-SoS was noted in 15 subjects (52%). The values of PTH were over a normal limit. In the whole group main factors negatively influencing current Ad-SoS values were duration of dialysis, age and PTH. The skeletal status in subjects with ESRD on hemodialysis was seriously affected, and longitudinal measurements showed its aggravation over a time of the study.

Skeletal status in adolescents with end-stage renal failure: a longitudinal study

In a longitudinal study, bone status was assessed in adolescents and young adults aged 15.3+/-3.4 years at the onset of the study with end-stage renal failure (ESRF). The group consisted of 18 subjects (11 females and seven males), of whom nine patients were on hemodialysis and nine patients on peritoneal dialysis. Six patients were previous or current glucocorticoid (GCS) users. Renal failure was recognized before 6.1+/-4.1 years, and dialysis was performed for 3.0+/-2.0 years. Follow-up took placed 8.6+/-0.8 and 21.7+/-2.5 months later, and the following data were collected: bone mineral density (BMD) at the spine (s-BMD) and total body (TB-BMD) using DPX-L (Lunar, USA); quantitative ultrasound by DBM 1200 (IGEA, Italy) at the hand phalanges (Amplitude-dependent Speed of Sound, Ad-SoS), serum concentration of i-PTH, total calcium, ionized calcium and phosphate. Tanner stages were also evaluated. The mean values of BMD measurements and Ad-SoS were stable during a period of observation, and a mean Z-score for TB-BMD was significantly lower at the third versus baseline value (-1.87+/-1.75 versus -1.49+/-1.53, P<0.05). Z-scores for s-BMD and Ad-SoS decreased non-significantly. Changes in s-BMD and TB-BMD Z-scores were influenced by changes in body size and changes in biochemical parameters, and a change in Ad-SoS Z-score was not dependent on these factors. The values of second (P<0.05) and third (P<0.01) s-BMD Z-score were significantly lower in GCS treated subjects, and longitudinal change in spine Z-score was greater in GCS treated patients versus others (P<0.05). Duration of ESRF, duration and type of dialysis and gender did not influence skeletal variables. Skeletal measurements correlated significantly with Tanner stages (besides the correlation with Ad-SoS in the first measurement, r ranged from 0.5 to 0.72, P<0.05), and changes in Tanner stages observed over a period of observation did not correlate with changes in skeletal variables. Among laboratory variables, the following non-significant tendencies to change were observed: serum concentration of i-PTH and phosphate increased, and total and ionized calcium decreased. In conclusion, adolescent subjects with ESRF treated with dialysis showed stable mean values of skeletal measurements, and these were expressed as Z-scores, a tendency to drop was observed. The lack of an increase observed in normal healthy subjects of the same age, and low values in Z-scores, indicates that skeletal status is seriously affected in subjects with ESRF.

Quantitative ultrasound at hand phalanges in adults with end-stage renal failure

The aim of this study was to assess bone status in 220 subjects with end-stage renal failure (ESRF) (146 men, mean age 53.0 +/- 13.9 years and 74 women, mean age 48.1 +/- 14.3 years). The duration of hemodialysis (durHD) and duration of renal insufficiency (durRI) were, in men, 2.6 +/- 3.8 years and 7.7 +/- 8.0 years, and, in women, 2.8 +/- 3.4 years and 9.1 +/- 7.6 years, respectively. ESRF was caused by the following reasons: chronic glomerulonephritis in 92 patients, diabetes in 52, chronic pyelonephritis in 37, polycystic kidney disease in 19, amyloidosis in 5, hypertension in 4 and unknown cause in 11. The control group consisted of 1615 normal healthy subjects (1216 women, mean age 48.1 +/- 12.1 years and 399 men, mean age 52.9 +/- 14.8 years). Mean age did not differ between patients and controls. Skeletal status was evaluated by quantitative ultrasound (US) measurements at the hand phalanges using DBM 1200 (IGEA, Italy) which measures amplitude-dependent speed of sound (Ad-SoS, m/s). The mean value of Ad-SoS in male patients was 1981 +/- 88 m/s, T-score -l2.03 +/- 1.26, Z-score -0.53 +/- 1.7 and, in female patients, 1967 +/- 96 m/s, -2.23 +/- 1.37, -1.41 +/- 1.56, respectively. Respective values in male controls were 2008 +/- 81 m/s, -1.66 +/- 1.16, -0.01 +/- 0.98 and, in female controls, 2026 +/- 81 m/s, -1.4 +/- 1.15, -0.74 +/- 0.86, and were significantly higher than in male (p < 0.001) and female (p < 0.0000001) patients. A correlation analysis of Ad-SoS with durHD and durRI showed that only in males did both factors significantly influence parameters measured (r = -0.26, p < 0.01). Multiple stepwise regression analysis of Ad-SoS on age, durHD, durRI, weight and height was possible to perform only in males and the following equation was established: Ad-SoS = 2545 m/s - 3.09 x age (years) - 5.68 x durHD (years) - 2.15 x height (cm) - 0.99 x durRI (years), p < 0.000001, r = 0.55, SEE = 69.6. Concluding, in subjects with ESRF treated with hemodialysis, skeletal status assessed with the use of quantitative US was affected.

Skeletal status in children and adolescents with chronic renal failure before onset of dialysis or on dialysis

Bone status was assessed in 15 children and adolescents with predialysis chronic renal failure (CRF) and in 25 subjects with end-stage renal failure (ESRF). The mean age in the whole group was 14.6+/-3.2 years and CRF had been recognized 5.8+/-4.0 years earlier. The mean age, body size, duration of the disease and Tanner stages did not differ significantly between patients with predialysis CRF and ESRF. The control group consisted of 890 healthy subjects matched with patients for age. Bone mineral density (BMD) was measured by DPX-L (Lunar, Madison, WI) at the spine (s-BMD) and total body (TB-BMD); quantitative ultrasound (QUS) was performed by DBM 1200 (IGEA, Italy) at the hand phalanges (Ad-SoS). Laboratory investigations included the evaluation of intact parathyroid hormone (i-PTH), total and ionized serum calcium, and serum phosphate. In the whole group of patients the following mean values were obtained: Ad-SoS 1952+/-79 m/s (significantly lower than in controls, who had Ad-SoS 2022+/-85 m/s, p<0.05; the difference remained significant after adjusting for body mass index), s-BMD 0.87+/-0.22 g/cm2 ( Z-score -1.6), TB-BMD 0.92+/-0.12 g/cm2 ( Z-score -1.44), i-PTH 276+/-300 pg/ml, total calcium 2.46+/-0.19 mmol/l, ionized calcium 1.14+/-0.08 mmol/l, phosphate 1.68+/-0.61 mmol/l. Skeletal measurements correlated significantly with age, body size and Tanner stages (also after adjusting for age), while significant correlations of these parameters with the duration of CRF and laboratory investigations (except of correlations of i-PTH with Ad-SoS and with TB-BMD in predialysis patients) were not observed. None of the studied variables differed significantly between predialysis and dialysis patients. In conclusion, both predialysis and dialysis children and adolescents showed a decrease in BMD and quantitative ultrasound measurements. The severity of skeletal alterations was similar in the early phase (predialysis patients) and end stage (dialysis patients) of the disease and did not show a tendency to progress with CRF duration.

Imaging of renal osteodystrophy

Chronic renal insufficiency, hemodialysis, peritoneal dialysis, renal transplantation and administration of different medications provoke complex biochemical disturbances of the calcium-phosphate metabolism with wide spectrum of bone and soft tissue abnormalities termed renal osteodystrophy. Clinically most important manifestation of renal bone disease includes secondary hyperparathyroidism, osteomalacia/rickets, osteoporosis, adynamic bone disease and soft tissue calcification. As a complication of long-term hemodialysis and renal transplantation amyloid deposition, destructive spondyloarthropathy, osteonecrosis, and musculoskeletal infections may occur. Due to more sophisticated diagnostic methods and more efficient treatment classical radiographic features of secondary hyperparathyroidism and osteomalacia/rickets are now less frequently seen. Radiological investigations play an important role in early diagnosis and follow-up of the renal bone disease. Although numerous new imaging modalities have been introduced in clinical practice (scintigraphy, CT, MRI, quantitative imaging), plain film radiography, especially fine quality hand radiograph, still represents most widely used examination.

A new serum assay to measure N-terminal fragment of telopeptide of type I collagen in patients with renal osteodystrophy

BACKGROUND: Up until now, there was little known about the use of bone resorption markers in the assessment of bone status in patients with chronic renal failure (CRF). The present study evaluated the ability of a new immunoassay for N-terminal telopeptide of type I collagen to assess bone turnover in a group of hemodialyzed patients. METHODS: The following parameters were measured in a fasting blood sample from 111 patients on maintenance hemodialysis for at least 2 years and in 120 healthy subjects: calcium, phosphorus, magnesium, BALP, PTH, and N-terminal telopeptide of type I collagen (NTx-ELISA, OSTEOMARK NTx Siero-Ostex International). RESULTS: Serum PTH, BALP, and NTx were significantly higher (P<0.001) in hemodialyzed (HD) patients than in healthy subjects. In HD patients, PTH was correlated to BALP and NTx (r=0.40 and 0.55, respectively). When combining PTH and BALP serum levels, 17 patients showed high turnover (HT) and 65 were found to have a normal to low turnover (N-LT). In HT patients, serum NTx and dialytic age were significantly (P<0.01) higher than in N-LT patients. Moreover, even after adjusting for age, body mass index, dialytic age, and calcium-vitamin D treatment, serum NTx discriminated between HT and N-LT with a sensitivity of 97.6% and a specificity of 90.9%. CONCLUSION: Although bone biopsy remains the reference method for the diagnosis of renal osteodystrophy, the combined use of markers of bone resorption and bone formation could improve the clinical management of renal bone diseases.

Quantitative ultrasound of the calcaneus and dual X-ray absorptiometry of the lumbar spine in assessment and follow-up of skeletal status in patients after kidney transplantation

Bone loss after kidney transplantation is a significant complication of immunosuppressive treatment leading to a high prevalence of bone fracture in these patients. The purpose of this study was to determine the usefulness of quantitative ultrasound (QUS) of the calcaneus in comparison with dual X-ray absorptiometry (DXA) of the lumbar spine in determining bone status and mineral changes in patients in the first 6 months after transplantation. Forty-six patients participated in the study (25 men and 21 women; age range 26-62 years, 102+/-66 months previously on dialysis). They were treated with cyclosporine, methylprednisolone, mycophenolate mofetil, and basiliximab. The 6-month cumulative steroid dose was 24.9+/-3.7 mg/kg body weight. Calcaneal QUS (Sahara, Hologic, Waltham, Mass.) and DXA (Hologic QDR 4500) of the lumbar spine were done in all patients within 3 weeks after transplantation and 6 months thereafter. Bone mineral density (BMD) of the lumbar spine measured by DXA decreased from 0.892+/-0.137 to 0.837+/-0.126 g/cm2 (p<0.0001) and the T score decreased from 1.84+/-1.29 standard deviation (SD) to 2.35+/-1.19 SD (p<0.0001) in the first 6 months after transplantation. The QUS parameters of the calcaneus were broadband ultrasound attenuation (BUA), speed of sound (SOS), and quantitative ultrasound index (QUI). The QUS parameters did not change significantly after the first 6 months. All QUS parameters correlated significantly with DXA BMD of the lumbar spine immediately after transplantation and 6 months thereafter. Significant decrease of the lumbar spine BMD in the first 6 months after transplantation was not accompanied by significant changes of calcaneal QUS parameters. The calcaneal QUS does not reflect bone mineral changes occurring in the lumbar spine and could not be a substitute for a direct-site DXA of the lumbar spine in the early period after kidney transplantation.

The use of ultrasound in the assessment of bone status

The assessment of skeletal status has wide clinical applications, especially in the management of osteoporosis. Osteoporosis, once thought of as an unpreventable and untreatable aging process, has revealed many of its secrets over the last decade, and the advent of successful drug therapy has changed our perception of the disease. Non-invasive techniques play a fundamental role in the diagnosis of osteoporosis and in the assessment of the efficacy of drug treatments. The primary technique used in osteoporosis is dual X-ray absorptiometry (DXA), that has been established as a reliable means of measuring bone density. Quantitative ultrasound (QUS), because of the relative portability of the equipment, ease of use, lack of ionizing radiation and low cost, has great potential for widespread use. Five devices for QUS assessment have recently been approved by the Food and Drug Administration and many more applications are in progress. QUS is a relatively new technology, at least in its application to bone fragility. Nevertheless, QUS has demonstrated that it is able to detect bone fragility as well as DXA. However, diagnosis of osteoporosis by QUS remains contentious, but the problems are due more to the limitations of the present T-scores rather than to the technique. A better option for QUS would be to report results in terms of remaining lifetime fracture risk, keeping in mind that a risk estimate needs not only the QUS or DXA measurement, but also the specific data, such as age, weight, gender, hormonal status and fracture history of the patient.

Diagnosis and monitoring of renal osteodystrophy

A variety of biochemical investigations and radiological techniques are available to assist in the diagnosis and monitoring of renal osteodystrophy. Measurement of serum parathyroid hormone remains the single most useful biochemical test in predicting bone histology in an individual patient. Newer biochemical markers of bone turnover are unlikely to supplant this in everyday practice, but may provide useful supplementary information in the future. The present review discusses the role of radiological investigation, including bone densitometry and quantitative ultrasound. Bone biopsy remains the 'gold standard' investigation. Its invasive nature and the need for specialized processing and interpretation limits its use in clinical practice, although it still has a role particularly in the investigation of low turnover states. Also, as molecular biological techniques are increasingly being used, the evaluation of biopsy specimens will in the future provide new insights into the disordered bone cell function that occurs in renal osteodystrophy.