Bone Histomorphometric Findings Research Articles

Histomorphometric reference data of transiliac bone biopsy in children from 8 to 17 years old.

Histomorphometric analysis of bone samples is a key tool for studying bone metabolism; however, only a few pediatric reference data exist. The aim of the present study is to report more reference data and to investigate if histomorphometric differences exist between age and gender. We obtained 19 transiliac bone samples previously marked with tetracycline, from children between 8 and 17 years (13 were male), with normal blood test results and urine biochemical bone markers. We evaluated bone histomorphometric parameters using a digitalizing table with osteomeasure to obtain normative data of means and standard deviations, as well as median and range. Due to the small sample, a Monte Carlo simulation was applied. Structural, static, dynamic, and resorptic histomorphometric parameters were evaluated by age and gender following the American Society for Bone and Mineral Research recommendations. Bone volume (in the older children) and mineral apposition rate (in the younger children), the eroded surface (in boys), and the new bone wall thickness (in girls) were significantly increased. On the trabecular area of mineralization front, the modeling and the remodeling bone formation were similar (16 and 18%). The rest of the histomorphometric bone parameters by age and gender showed no significant difference. In healthy children, these bone histomorphometric findings, with these techniques and for this ages could be used as reference values.

Vascular calcification in peritoneal dialysis patients and its association with bone-derived molecules and bone histomorphometry

IntroductionData regarding vascular calcification (VC) in contemporary peritoneal dialysis (PD) patients is scarce. Bone–vascular axis has been demonstrated in hemodialysis (HD). However, studies showing the link between bone disease and VC in PD patients are lacking. The role of sclerostin, dickkopf-related protein 1 (DKK-1), receptor activator for nuclear factor kB ligand and osteoprotegerin (OPG) in VC in PD remains to clarify. Materials and methodsBone biopsy was performed in 47 prevalent PD patients with histomorphometric analysis. Patients were submitted to pelvis and hands X-ray to evaluate VC using the Adragão score (AS). Relevant clinical and biochemical data was collected. ResultsThirteen patients (27.7%) had positive AS (AS≥1). Patients with VC were significantly older (58.9 vs. 50.4 years, p=0.011), had a lower dialysis dose (KT/V 2.0 vs. 2.4, p=0.025) and a higher glycosylated hemoglobin (7.2 vs. 5.4%, p=0.001). There was not any laboratorial parameter of mineral and bone disease used in clinical practice different between patients with or without VC. All diabetic patients had VC but only 8.1% of non-diabetic had VC (p<0.001). Patients with VC showed significantly higher erythrocyte sedimentation rate (ESR) (91.1 vs. 60.0mm/h, p=0.001), sclerostin (2250.0 vs. 1745.8pg/mL, p=0.035), DKK-1 (1451.6 vs. 1042.9pg/mL, p=0.041) and OPG levels (2904.9 vs. 1518.2pg/mL, p=0.002). On multivariate analysis, only ESR remained statistically significant (OR 1.07; 95% CI 1.01–1.14; p=0.022). Bone histomorphometric findings were not different in patients with VC. There was no correlation between bone formation rate and AS (r=−0.039; p=0.796). ConclusionThe presence of VC was not associated with bone turnover and volume evaluated by bone histomorphometry. Inflammation and diabetes seem to play a more relevant role in VC in PD.

Vascular calcification in peritoneal dialysis patients and its association with bone-derived molecules and bone histomorphometry

IntroductionData regarding vascular calcification (VC) in contemporary peritoneal dialysis (PD) patients is scarce. Bone–vascular axis has been demonstrated in hemodialysis (HD). However, studies showing the link between bone disease and VC in PD patients are lacking. The role of sclerostin, dickkopf-related protein 1 (DKK-1), receptor activator for nuclear factor kB ligand and osteoprotegerin (OPG) in VC in PD remains to clarify. Materials and methodsBone biopsy was performed in 47 prevalent PD patients with histomorphometric analysis. Patients were submitted to pelvis and hands X-ray to evaluate VC using the Adragão score (AS). Relevant clinical and biochemical data was collected. ResultsThirteen patients (27.7%) had positive AS (AS≥1). Patients with VC were significantly older (58.9 vs. 50.4 years, p=0.011), had a lower dialysis dose (KT/V 2.0 vs. 2.4, p=0.025) and a higher glycosylated hemoglobin (7.2 vs. 5.4%, p=0.001). There was not any laboratorial parameter of mineral and bone disease used in clinical practice different between patients with or without VC. All diabetic patients had VC but only 8.1% of non-diabetic had VC (p<0.001). Patients with VC showed significantly higher erythrocyte sedimentation rate (ESR) (91.1 vs. 60.0mm/h, p=0.001), sclerostin (2250.0 vs. 1745.8pg/mL, p=0.035), DKK-1 (1451.6 vs. 1042.9pg/mL, p=0.041) and OPG levels (2904.9 vs. 1518.2pg/mL, p=0.002). On multivariate analysis, only ESR remained statistically significant (OR 1.07; 95% CI 1.01–1.14; p=0.022). Bone histomorphometric findings were not different in patients with VC. There was no correlation between bone formation rate and AS (r=−0.039; p=0.796). ConclusionThe presence of VC was not associated with bone turnover and volume evaluated by bone histomorphometry. Inflammation and diabetes seem to play a more relevant role in VC in PD.

MO574MINERAL AND BONE DISORDERS CHANGES IN RENAL TRANSPLANTED PATIENTS

Abstract Background and Aims Successful renal transplant restores many physiologic abnormalities, including improvement of chronic kidney disease- mineral and bone disorder (CKD-MBD) syndrome. The primary aims of this study were: analyse the changes and evolution of the 3 components of CKD-MBD pre and 1 year post renal transplantation: the mineral abnormalities, the bone disorders and the vascular calcifications; and to correlate fibroblast grow factor 23 (FGF23), klotho and sclerostin serum levels with bone histomorphometric parameters and CV disease. The secondary aims were to study the evolution of other bone related parameters and correlate those with bone biopsies data, as well as to validate Adragão vascular calcification score in a population of renal transplant patients. Method We performed a prospective cohort study of a consecutive sample of de novo single renal transplanted patients in our unit. At inclusion, demographic, clinical and transplant-related data were collected, X-ray of the pelvis and hands (for Adragão score) and echocardiographic findings were recorded. All patients were submitted to a bone biopsy and laboratorial evaluation at baseline (time 0 – T0). Patients were followed for 12 months (time 1 – T1), after which performed laboratorial evaluation, a 2nd bone biopsy, echocardiogram, X-ray of pelvis and hands, bone densitometry and non-contrast cardiac CT (Agatston score). Continuous variables are presented as medians and categorical variables as frequencies. Differences between T0 and T1 were accessed by Wilcoxon matched-pairs test and paired McNemar test. Correlations between bone histomorphometric findings and severity of vascular calcifications with demographic and laboratorial parameters were obtained with Wilcoxon rank-sum test or Kruskall Wallis test. STATA software was used and p &amp;lt; 0.05 was considered statistically significant. Results We recruited 84 patients in a 28 month-period. At the end of 12 months, 69 patients performed a 2nd evaluation. Median age 53 years, 48 men, 53 caucasian, median dialysis vintage 55 months. We observe a significant reduction on phosphorus, magnesium, PTH, calcitonin, sclerostin, bone alkaline phosphatase and FGF23. Both calcium and alpha-klotho serum levels increase, with no significant changes in vitamin D levels. 68% of the patients presented renal osteodystrophy at the 2nd bone biopsy, and we observed a significant increase in the development of low turnover bone disorder, with no major changes in volume or mineralization. Changes in alpha-klotho, bAP and sclerostin (from T0 to T1) were important determinants of changes in turnover, mineralization and volume, respectively. Despite not being statistically significant, we were able to observe an improvement in the cortical bone porosity. Vascular calcifications and echocardiographic findings weren’t different comparing to the baseline (Median Adragão score was 1 in both evaluations, and valve calcifications were present in 22% and 23% of patients, with no changes in LVMI). The median Agatston score was 48.5, being the median adjusted percentile of 82%. FGF23 and sclerostin were found to be independent risk factors for extra-osseous calcifications, as well as low bone volume, cortical porosity and osteoid volume. Adragão score and valve calcifications correlated well with the increased severity of coronary calcifications determined by Agatston score (absolute and percentile). Conclusion In conclusion, renal transplantation improves two of the three components of CKD-MBD (biochemical and bone disorders), slowing the progression of vascular calcifications. FGF23, sclerostin and bAP seemed to be key parameters in understanding the bone changes observed in post transplant period, and these hormones also interfere with extra osseous calcification severity. Adragão score seems to be a good tool to access vascular calcifications in renal transplanted patients.

Circulating Levels of Dickkopf-Related Protein 1 Decrease as Measured GFR Declines and Are Associated with PTH Levels

Background: The Wnt/β-catenin pathway has been implicated in the development of adynamic bone disease in early-stage chronic kidney disease (CKD). Dickkopf-related protein 1 (DKK1) and sclerostin are antagonists of the Wnt/β-catenin pathway yet have not been widely used as clinical indicators of bone disease. This study characterized levels of DKK1, sclerostin, and other biomarkers of mineral metabolism in participants across a spectrum of inulin-measured glomerular filtration rate (GFR). Methods: GFR was measured by urinary inulin clearance (mGFR) in 90 participants. Blood samples were obtained for measurement of circulating DKK1, sclerostin, fibroblast growth factor 23 (FGF-23), parathyroid hormone (PTH), calcium, phosphate, α-klotho, and vitamin D metabolites including 25-hydroxyvitamin D₃ and 1,25-dihydroxyvitamin D₃. Spearman correlations and linear regressions were used where appropriate to examine the associations between measured values. Results: The median [IQR] age was 64 years [53.0–71.0], and the median [IQR] mGFR was 32.6 [21.7–60.6] mL/min. DKK1 decreased (r = 0.6, p < 0.001) and sclerostin increased (r = −0.4, p < 0.001) as kidney function declined, and both were associated with phosphate, PTH, FGF-23, and 1,25-dihydroxyvitamin D₃ in the unadjusted analysis. After adjustment for age and mGFR, DKK1 remained significantly associated with PTH. Conclusion: The results of this study demonstrate opposing trends in Wnt/β-catenin pathway inhibitors, DKK1 and sclerostin, as mGFR declines. Unlike sclerostin, DKK1 levels decreased significantly as mGFR declined and was independently associated with PTH. Future studies should determine whether measurement of Wnt signaling inhibitors may be useful in predicting bone histomorphometric findings and important clinical outcomes in patients with CKD.

Bone Formation Parameters of the Biopsied Ilium Differ between Subtrochanteric and Diaphyseal Atypical Femoral Fractures in Bisphosphonate-Treated Patients.

Atypical femoral fractures (AFFs) are defined as atraumatic or low-trauma fractures located in the subtrochanteric or diaphyseal sites. Long-term bisphosphonates (BPs) are administered to prevent fragility fractures in patients with primary osteoporosis or collagen diseases who are already taking glucocorticoids (GCs). Long-term BP use is one of the most important risk factors for AFFs. Its pathogenesis is characterized by severely suppressed bone turnover (SSBT), but whether the characteristics of patients are different regarding to location of fracture site remains unknown. In this study, we compared the characteristics and bone histomorphometric findings between subtrochanteric and diaphyseal sites in patients with BP-associated AFFs. Nine women with BP-associated AFFs were recruited, including 3 with systemic lupus erythematosus, 2 with rheumatoid arthritis, 2 with primary osteoporosis, 1 with polymyalgia rheumatica, and 1 with sarcoidosis. Patients were divided into the subtrochanteric group (n = 5; average age, 52 years; BP treatment, 5.9 years) and the diaphyseal group (n = 4; average age, 77 years; BP treatment, 2.6 years). Compared with the diaphyseal group, the subtrochanteric group had significantly higher daily GC doses (average, 10.9 vs. 2.3 mg/day) and significantly lower serum 25-hydroxyvitamin-D levels (17.8 vs. 25.6 ng/mL). Bone histomorphometry of the biopsied iliac bone showed SSBT in 3 cases (subtrochanteric, n = 1; diaphyseal, n = 2). Osteoid volume and trabecular thickness were significantly lower in the subtrochanteric group than in the diaphyseal group. Bone formation was inhibited more severely in subtrochanteric than in the diaphyseal group due to the higher GC doses used.

Pediatric solid organ transplantation and osteoporosis: a descriptive study on bone histomorphometric findings

Organ transplantation may lead to secondary osteoporosis in children. This study characterized bone histomorphometric findings in pediatric solid organ transplant recipients who were assessed for suspected secondary osteoporosis. Iliac crest biopsies were obtained from 19 children (7.6-18.8 years, 11 male) who had undergone kidney (n = 6), liver (n = 9), or heart (n = 4) transplantation a median 4.6 years (range 0.6-16.3 years) earlier. All patients had received oral glucocorticoids at the time of the biopsy. Of the 19 patients, 21 % had sustained peripheral fractures and 58 % vertebral compression fractures. Nine children (47 %) had a lumbar spine BMD Z-score below -2.0. Histomorphometric analyses showed low trabecular bone volume (< -1.0 SD) in 6 children (32 %) and decreased trabecular thickness in 14 children (74 %). Seven children (37 %) had high bone turnover at biopsy, and low turnover was found in 6 children (32 %), 1 of whom had adynamic bone disease. There was a great heterogeneity in the histological findings in different transplant groups, and the results were unpredictable using non-invasive methods. The observed changes in bone quality (i.e. abnormal turnover rate, thin trabeculae) rather than the actual loss of trabecular bone, might explain the increased fracture risk in pediatric solid organ transplant recipients.

Osteomalacia with Bone Marrow Fibrosis Due to Severe Vitamin D Deficiency After a Gastrointestinal Bypass Operation for Severe Obesity

To present 5 cases of bone biopsy-proven osteomalacia with marrow fibrosis (in 3 cases) after gastric bypass operation, review the relevant literature, and offer preventive strategies. We summarize the clinical presentation, pertinent biochemical and radiologic data, and bone histomorphometric findings in 5 patients, encountered during a period of 17 years, in whom severe vitamin D deficiency developed after a gastrointestinal bypass surgical procedure for morbid obesity. Five patients (39 to 60 years of age) were seen for evaluation of metabolic bone disease not responding to "usual" therapy after a gastric bypass surgical procedure. All had generalized bone pain and tenderness, muscle weakness, stooping posture, difficulty walking, and waddling gait due to severe proximal muscle weakness for a period of 2 to 5 years. Diagnoses before the referral varied from arthritis and gout to vitamin D deficiency and osteoporosis despite highly suggestive biochemical or radiologic findings (or both) of osteomalacia in each patient, which was confirmed by bone biopsy. After therapy with pharmacologic doses of ergocalciferol (100,000 IU daily) and calcium carbonate (1 to 2.5 g daily), considerable improvements occurred in clinical symptoms and functional status, biochemical indices, bone mineral density, and bone histomorphometric features. Gastric bypass operations predispose patients to severe vitamin D deficiency and osteomalacia in the absence of pharmacologic doses of vitamin D therapy. In general, the current recommendations are grossly inadequate in this high-risk population, and the clinical presentation is both nonspecific and often misleading. Prospective long-term studies are needed to determine the appropriate vitamin D dose required to prevent osteomalacia in such patients.

Histological characteristics and prevalence of secondary osteoporosis in systemic mastocytosis. A retrospective analysis of 158 cases

Mastocytosis is characterized by abnormal proliferation of mast cells especially within the skin and bone marrow and is often associated with osteoporosis. Mast cells can synthesize a variety of cytokines that are known to affect the skeletal system, but the cellular and pathophysiological mechanisms leading to osteoporosis in systemic mastocytosis remain poorly understood. To further characterize mastocytosis-associated osteoporosis we compared bone histomorphometric findings in iliac crest biopsy specimens from 158 untreated patients with mastocytosis. The overall prevalence of mastocytosis in the specimens diagnosed with osteoporosis was 1.25%, but that in patients younger than 45 years was 2.25%. The male-to-female ratio was 1:1, in contrast to 1:2 in osteoporosis. Osteopenia was present in 64% of the patients with mastocytosis, while osteosclerosis was rare (3%). Histological criteria are the concentric increase in mast cells in the perivascular tissue and the increase in elongated mast cells within the marrow space. Histomorphometry showed mastocytosis to be associated with moderate hyperosteoidosis and increased perforating bone resorption, indicated by a significant decrease in bone volume, trabecular thickness, and trabecular number as compared to controls. Osteoclast number was not altered, pointing to a functional effect of mast cells and/or its product on osteoclasts, rather than an effect on osteoclast differentiation. We conclude that although the prevalence of mastocytosis seems to be low, its correct and early diagnosis is crucial for at least 2.25% of younger patients with osteoporosis.

Bone remodeling alterations in myelodysplastic syndrome

There is a close relationship between hematopoietic bone marrow and bone cells. Thus, the profound derangement of hematopoiesis in myelodysplastic syndromes (MDS) might be expected to affect bone cell function. We studied the dynamic histomorphometric changes in bone in 22 MDS patients to examine this relationship and analyze the influence of hematological disease on bone remodeling. Bone-regulating hormones and histomorphometry of undecalcified transiliac bone biopsies, after double tetracycline labeling, were studied. Serum calcium, phosphorus, creatinine, alkaline phophatase, osteocalcin, iPTH, 25(OH)D 3, 1,25(OH) 2D 3, hydroxyprolinuria, and calcium/creatinine ratio in urine were normal compared with controls. Histomorphometry showed a significant decrease in osteoblast surface (Ob.S/BS) (0.30 ± 0.40 vs. 0.8 ± 1.1, p = 0.031), wall thickness (W.Th), (22.03 ± 5.5 vs. 31.8 ± 5.8, p < 0.005), osteoclast number (N.Oc/T.Ar) (0.004 ± 0.01 vs. 0.017 ± 0.01, p = 0.03), mineral apposition rate (MAR) (0.16 ± 0.15 vs. 0.53 ± 0.19, p < 0.005), bone formation rate, surface referent (BFRBS) (0.004 ± 0.10 vs. 0.016 ± 0.016, p = 0.009), and activation frequency (Ac.f) (0.06 ± 0.07 vs. 0.21 ± 0.23, p = 0.008). An increase in mineralization lag time (MLT) (119.2 ± 78.6 vs. 29.6 ± 77, p < 0.005), (mean ± SD, unpaired Student t-test) was observed. Bone volume (BV/TV), eroded surfaces (ES/BS), and osteoid thickness (O.Th) remained unchanged. This picture of adynamic bone with decreased mineral apposition rate and markedly decreased osteoclast number is a characteristic finding in MDS patients. Thus, bone histomorphometric findings in MDS patients show the relationships and interactions between hematopoietic and bone cells.

Humoral hypercalcemia of malignancy in canine lymphosarcoma.

Studies on the pathogenesis of hypercalcemia in canine lymphosarcoma have led to conflicting results. The biochemical and bone histomorphometric findings in canine lymphosarcoma were examined in 19 hypercalcemic and 17 nonhypercalcemic dogs with lymphosarcoma. Compared to the nonhypercalcemic group, the hypercalcemic dogs demonstrated an increase in fasting and 24-h calcium excretion, an increase in fractional phosphorus excretion, and a significant increase in nephrogenous AMP excretion. Plasma 1,25-dihydroxyvitamin D and immunoreactive PTH levels were equivalent in the two groups. Quantitative bone histomorphometry performed on iliac crest biopsies revealed increased parameters of bone resorption in those hypercalcemic dogs with no evidence of tumor at the biopsy site, without a compensatory increase in bone formation. Acid-urea tumor tissue extracts from eight hypercalcemic and six nonhypercalcemic dogs were examined for adenylate cyclase-stimulating activity (ACSA). All tumors from hypercalcemic dogs contained ACSA, whereas none of the tumors from nonhypercalcemic dogs had ACSA. Further purification of one tumor extract yielded an adenylate cyclase-stimulating protein which appeared to interact specifically with the PTH receptor. We conclude that in some cases, hypercalcemia in canine lymphosarcoma is mediated by a tumor-derived circulating bone-resorbing factor which is distinct from PTH. ACSA detected in tumor tissue appears to be a reliable marker for the syndrome in vivo. The role of this activity in the pathogenesis of the syndrome remains to be determined.