Percutaneous bone biopsy in the diagnosis of renal osteodystrophy

Skeletal manifestations in end-stage renal disease patients and relation to FGF23 and Klotho

Chronic kidney disease affects patients of all ages and, as it progresses, it greatly affects their lives, especially with the complications it causes. One major complication is renal osteodystrophy (ROD) which starts to develop from the early stages of the disease, but becomes most apparent in patients in need of renal replacement therapy. Diagnosing ROD in the early stages remains a challenge, which brings up the need to find novel biomarkers. Studies are focusing on the role of fibroblast growth factor 23 and Klotho in the bone and mineral homeostasis, but the results are conflicting. ROD remains a major complication in CKD patients, therefore we need to gain a better understanding from the pathophysiological point of view, in order to be able to adjust the medical therapy.

Impact of secondary hyperparathyroidism on disease progression, healthcare resource utilization and costs in pre-dialysis CKD patients

BACKGROUND AND OBJECTIVES

Secondary hyperparathyroidism (SHPT) can lead to significant morbidity, mortality, and additional healthcare resource utilization in chronic kidney disease (CKD) stage 5. The objective of this study was to examine healthcare costs and utilization, and the risks of dialysis or mortality, among pre-dialysis CKD patients with and without SHPT.

RESEARCH DESIGN AND METHODS

This retrospective cohort study examined insurance claims from 66 644 adult, pre-dialysis, CKD patients with and without SHPT during a 72-month period. Annualized estimates of healthcare costs and utilization, and disease progression to dialysis or death following index CKD diagnosis were compared.

RESULTS

Post-index annualized costs and inpatient healthcare resource utilization was higher in those with SHPT in both unadjusted and adjusted (controlling for gender, age, plan type, payer type, geographic region, physician specialty, pre-index co-morbidities, and pre-index total healthcare costs), and unmatched and matched analyses. Kaplan-Meier analysis demonstrated that the rate of progression to dialysis or death was higher for CKD with SHPT compared to CKD without SHPT, and Cox proportional hazard models suggested that CKD patients with SHPT were more than four to five times as likely to initiate dialysis or die as compared to CKD without SHPT.

CONCLUSION

SHPT in pre-dialysis CKD patients is associated with significantly greater healthcare costs, inpatient hospitalizations, and a faster rate of disease progression compared to pre-dialysis CKD without SHPT. Since observational studies are designed to demonstrate associations rather than causality, further investigation is required to confirm these findings.

Oral paricalcitol for the treatment of secondary hyperparathyroidism in patients on hemodialysis or peritoneal dialysis

BACKGROUND/AIMS

Secondary hyperparathyroidism is a common complication of chronic kidney disease, resulting from inactivation of vitamin D receptor signaling and phosphate retention. Selective activation of vitamin D receptors with intravenous paricalcitol significantly reduced parathyroid hormone (PTH) levels with no significant hypercalcemia or hyperphosphatemia in predialysis and hemodialysis (HD) patients. This study investigates the effects of oral paricalcitol to reduce PTH in patients receiving chronic HD and peritoneal dialysis (PD).

METHODS

Eighty-eight patients were randomized in double-blind fashion to receive paricalcitol or placebo for 12 weeks. The dose of the study drug was adjusted weekly using the previous week's intact PTH (iPTH) level as well as calcium and Ca x P product levels. The primary end points were efficacy (two consecutive iPTH decreases of >or=30%) and safety (two consecutive calcium measurements >11.0 mg/dl). Markers of biochemical bone activity were followed.

RESULTS

Demographic characteristics were similar between treatment groups. The mean paricalcitol doses (three times a week) over the entire treatment period for subjects with baseline iPTH <or=500 pg/ml and iPTH >500 pg/ml were 3.9 and 7.6 microg, respectively. A statistically significant decrease in iPTH was seen after week 1, with a mean 30% reduction occurring by week 3. A significantly greater proportion of both HD and PD paricalcitol subjects [83% (33/40) and 100% (18/18), respectively] achieved two consecutive >or=30% decreases in iPTH. The treatment groups were not statistically different in regard to the hypercalcemia safety end point. Phosphate binder use and mean serum phosphorus levels were not different between the treatment groups. The markers of bone activity improved in the treated subjects and worsened in those on placebo.

CONCLUSION

Paricalcitol provides a rapid and sustained reduction of PTH in both HD and PD patients with minimal effect on serum calcium and phosphorus and no significant difference in adverse events as compared with placebo.

Definition, evaluation, and classification of renal osteodystrophy: a position statement from Kidney Disease: Improving Global Outcomes (KDIGO)

Disturbances in mineral and bone metabolism are prevalent in chronic kidney disease (CKD) and are an important cause of morbidity, decreased quality of life, and extraskeletal calcification that have been associated with increased cardiovascular mortality. These disturbances have traditionally been termed renal osteodystrophy and classified based on bone biopsy. Kidney Disease: Improving Global Outcomes (KDIGO) sponsored a Controversies Conference on Renal Osteodystrophy to (1) develop a clear, clinically relevant, and internationally acceptable definition and classification system, (2) develop a consensus for bone biopsy evaluation and classification, and (3) evaluate laboratory and imaging markers for the clinical assessment of patients with CKD. It is recommended that (1) the term renal osteodystrophy be used exclusively to define alterations in bone morphology associated with CKD, which can be further assessed by histomorphometry, and the results reported based on a unified classification system that includes parameters of turnover, mineralization, and volume, and (2) the term CKD-Mineral and Bone Disorder (CKD-MBD) be used to describe a broader clinical syndrome that develops as a systemic disorder of mineral and bone metabolism due to CKD, which is manifested by abnormalities in bone and mineral metabolism and/or extra-skeletal calcification. The international adoption of these recommendations will greatly enhance communication, facilitate clinical decision-making, and promote the evolution of evidence-based clinical practice guidelines worldwide.

Insuffizienzfrakturen in der Rheumatologie

Stress fractures occur as insufficiency fractures, with a prevalence of 0.8% in patients with rheumatological illness. The main sites of insufficiency fractures are the pelvis and sacrum, parts of the tibia and fibula that are close to the joints, and the calcaneus and hip. Since the painful symptoms overlap with the clinical picture of the painful joint diseases and because of the low sensitivity of conventional diagnostic X-ray, insufficiency fractures are not diagnosed directly or their diagnosis is delayed. The high sensitivity of computer tomography, skeletal scintigraphy and nuclear magnetic resonance imaging should be exploited in the diagnosis of insufficiency fractures. The case report presented describes insufficiency fractures of the distal right tibia and fibula in an elderly female patient with rheumatoid arthritis being treated with long-term glucocorticoids. In addition to advanced age, female gender, immobility and rheumatoid arthritis requiring long-term cortisone, there are further risk factors for insufficiency fractures: fluoride treatment over many years in the past, hypovitaminosis D3, renal failure. The DXA bone density values of the neck of the femur and the lumbar vertebrae do not show any osteoporosis, and the calcium concentration in the serum is low; phosphate is raised and parathormone is normal; osteocalcin, beta crosslaps and alkaline phosphatase are raised. Bone biopsy specimens taken from the iliac crest and the proximal femur and investigated for the purpose of differential diagnosis revealed renal osteopathy with secondary hyperparathyroidism and osteomalacia. In elderly patients with kidney failure, the possibility of renal osteopathy must be considered as the possible cause of reduced bone quality with a raised risk of insufficiency fractures, even when the parathormone levels are normal. In view of the frequency of osteopathies in rheumatological patients, osteology is of enormous significance in rheumatology.

Function and effect of bone morphogenetic protein-7 in kidney bone and the bone-vascular links in chronic kidney disease

In two independent and separate studies, we have shown that renal injury and chronic kidney disease (CKD) directly inhibit skeletal anabolism, and that stimulation of bone formation decreased the serum phosphate. In the first study, the serum Ca PO(4), parathyroid hormone (PTH), and calcitriol were maintained normal after renal ablation in mice, and even mild renal injury equivalent to stage 3 CKD decreased bone formation rates. More recently, these observations were rediscovered in low-density lipoprotein receptor null (LDLR-/-) mice fed high-fat/cholesterol diets, a model of the metabolic syndrome (hypertension, obesity, dyslipidemia and insulin resistance). We demonstrated that these mice have vascular calcification (VC) of both the intimal atherosclerotic type and medial calcification. We have also shown that VC is made worse by CKD and ameliorated by bone morphogenetic protein-7 (BMP-7). The finding that high-fat fed LDLR-/- animals with CKD had hyperphosphatemia which was prevented in BMP-7-treated animals lead us to examine the skeletons of these mice. It was found that significant reductions in bone formation rates were associated with high-fat feeding, and superimposing CKD resulted in the adynamic bone disorder (ABD), while VC was made worse. The effect of CKD to decrease skeletal anabolism (decreased bone formation rates and reduced number of bone modelling units) occurred despite secondary hyperparathyroidism. The BMP-7 treatment corrected the ABD and hyperphosphatemia, owing to BMP-7-driven stimulation of skeletal phosphate deposition reducing plasma phosphate and thereby removing a major stimulus to VC. A pathological link between abnormal bone mineralization and VC through the serum phosphorus was demonstrated by the partial effectiveness of directly reducing the serum phosphate by a phosphate binder that had no skeletal action. Thus, in the metabolic syndrome with CKD, a reduction in bone forming potential of osteogenic cells leads to the ABD producing hyperphosphatemia and VC, processes ameliorated by BMP-7, in part through increased bone formation and skeletal deposition of phosphate and in part through direct actions on vascular smooth muscle cells. We have demonstrated that the processes leading to vascular calcification begin with even mild levels of renal injury affecting the skeleton before demonstrable hyperphosphatemia and that they are preventable and treatable. Therefore, early intervention in the skeletal disorder associated with CKD is warranted and may affect mortality of the disease.

Renal osteodystrophy

The incidence of chronic renal disease is increasing, and the pattern of renal osteodystrophy seems to be shifting from the classic hyperparathyroid presentation to one of low bone turnover. Patients with persistent disease also live longer than previously and are more physically active. Thus, patients may experience trauma as a direct result of increased physical activity in a setting of weakened pathologic bone. Patient quality of life is primarily limited by musculoskeletal problems, such as bone pain, muscle weakness, growth retardation, and skeletal deformity. Chronic renal disease also increases the risk of comorbidity, such as infection, bleeding, and anesthesia-related problems. Current treatment strategies include dietary changes, plate-and-screw fixation, and open reduction and internal fixation.

A comparison of dosing regimens of paricalcitol capsule for the treatment of secondary hyperparathyroidism in CKD stages 3 and 4

BACKGROUND

Intermittent dosing of calcitriol for secondary hyperparathyroidism (SHPT) has been associated with greater parathyroid hormone (PTH) reduction with fewer calcemic and phosphatemic effects than daily (QD) dosing.

METHODS

Secondary analyses of three randomized, double-blind, placebo-controlled multicenter studies in stage 3 and 4 chronic kidney disease (CKD) patients with SHPT were performed to compare three times per week (TIW) with QD dosing of paricalcitol. The pharmacokinetics of TIW and QD dosing of paricalcitol capsules were assessed in a separate group of healthy subjects.

RESULTS

Pharmacokinetics revealed similar steady state paricalcitol exposure between dosing regimens. In CKD patients, baseline data were similar between the TIW studies (n = 72, paricalcitol; n = 73, placebo) and QD studies (n = 35, paricalcitol; n = 40, placebo). Both dosing regimens resulted in similar efficacy (91%) for the primary end point of two consecutive > or = 30% decreases in intact PTH from baseline, but the QD regimen resulted in a greater percent reduction in intact PTH from baseline. The chances for developing increased serum calcium and phosphorus levels or Ca x P product were similar between paricalcitol and placebo groups for both treatment regimens. Furthermore, no difference in the risk for these elevations was detected between the TIW and QD regimens.

CONCLUSIONS

QD dosing of paricalcitol capsules is as efficacious as TIW dosing in achieving the primary end point (2 consecutive > or = 30% reductions in PTH) in stage 3 and 4 CKD patients with SHPT. Moreover, the QD regimen had no significant effect on hypercalcemia, hyperphosphatemia or Ca x P product as compared with placebo or intermittent dosing.

Barriers to successful care for chronic kidney disease

Background

The National Kidney Foundation has formulated clinical practice guidelines for patients with chronic kidney disease (K/DOQI). However, little is know about how many patients actually achieve these goals in a dedicated clinic for chronic kidney disease.

Methods

We performed a cross-sectional analysis of 198 patients with an estimated glomerular filtration rate of less than 30 ml/min/1.73 m² and determined whether K/DOQI goals were met for calcium, phosphate, calcium-phosphate product, parathyroid hormone, albumin, bicarbonate, hemoglobin, lipids, and blood pressure.

Results

We found that only a small number of patients achieved K/DOQI targets. Recent referral to the nephrologist, failure to attend scheduled clinic appointments, African American ethnicity, diabetes, and advanced renal failure were significant predictors of low achievement of K/DOQI goals.

Conclusion

We conclude that raising awareness of chronic kidney disease and K/DOQI goals among primary care providers, early referral to a nephrologist, the exploration of socioeconomic barriers and cultural differences, and both patient and physician education are critical to improve CKD care in patients with Stage 4 and 5 CKD.

Bone disease in patients with chronic kidney disease under conservative management

CONTEXT AND OBJECTIVE

Few studies have focused on bone disease in patients with chronic kidney disease under conservative treatment. The objective was to evaluate bone disease in patients with chronic kidney disease.

DESIGN AND SETTING

Case series, at the Nephrology Division, Hospital Universitário Pedro Ernesto.

METHODS

131 patients with creatinine clearance from 10 to 60 ml/min/1.73 m(2) were followed up for at least one year. Serum creatinine, albumin, calcium, phosphorus, alkaline phosphatase, total CO2 (tCO2), intact parathyroid hormone (iPTH), and alkaline phosphatase were measured. Creatinine clearance was calculated from 24-hour urine creatinine measurements and protein ingestion estimates from urea assays.

RESULTS

Patients presenting creatinine clearance < 30 ml/min/1.73 m(2) had higher iPTH values, but normal serum levels for calcium, phosphorus, alkaline phosphatase and tCO2. Patients presenting iPTH values of twice the normal upper limit (144 pg/ml) showed lower tCO2 values. Bone alkaline phosphatase was evaluated in 37 patients with creatinine clearance < 30 ml/min/1.73 m(2), showing correlation with alkaline phosphatase but not with parathyroid hormone. Bone biopsy on nine patients with creatinine clearance < 30 ml/min/1.73 m(2) and iPTH > 144 pg/ml showed osteitis fibrosa (4), mild lesion (4) and high turnover (1).

CONCLUSION

The present data suggest the importance of early control for iPTH and metabolic acidosis, among patients under conservative management for chronic kidney disease, in order to prevent complications related to bone disease.