Renal bone disease: radiological investigation

Imaging in Chronic Kidney Disease-Metabolic Bone Disease

Musculoskeletal manifestations in chronic kidney disease (CKD) are the result of a series of complex alterations in mineral metabolism, which has been defined as chronic kidney disease - mineral and bone-related disorder (CKD-MBD). Biochemical assessment and, at times, bone biopsy remains the mainstay of disease assessment, however, radiological imaging is an important adjunct in evaluating disease severity. This review aims to illustrate the radiological features of CKD-MBD, such as secondary hyperparathyroidism, osteomalacia, adynamic bone disease, osteopenia, and extra-skeletal calcifications.

Pulmonary calciphylaxis associated with acute respiratory and renal failure due to cryptogenic hypercalcemia: an autopsy case report

Metastatic calcification is rare; it is found during autopsy in patients who underwent hemodialysis. Diffuse calcium precipitation of small and medium-sized cutaneous vessels, known as calciphylaxis, can result in progressive tissue necrosis secondary to vascular calcification. This condition most commonly involves the skin; however, a rare occurrence of visceral calciphylaxis has been reported. Here we report on an autopsy case. Despite a thorough evaluation, and even performing an autopsy, the underlying cause of acute-onset hypercalcemia, resulting in the production of pulmonary calciphylaxis and metastatic renal calcification associated with acute respiratory and renal failure, could not be determined. Metastatic calcification often lacks specific symptoms, and the degree of calcification is a marker of the severity and chronicity of the disease. This unusual autopsy case emphasizes the importance of rapidly progressing visceral calciphylaxis, as well as its early detection.

A 1-year randomized, double-blind, placebo-controlled study of intravenous ibandronate on bone loss following renal transplantation

The clinical profile of ibandronate as add-on to calcitriol and calcium was studied in this double-blind, placebo-controlled trial of 129 renal transplant recipients with early stable renal function (≤ 28 days posttransplantation, GFR ≥ 30 mL/min). Patients were randomized to receive i.v. ibandronate 3 mg or i.v. placebo every 3 months for 12 months on top of oral calcitriol 0.25 mcg/day and calcium 500 mg b.i.d. At baseline, 10 weeks and 12 months bone mineral density (BMD) and biochemical markers of bone turnover were measured. The primary endpoint, relative change in BMD for the lumbar spine from baseline to 12 months was not different, +1.5% for ibandronate versus +0.5% for placebo (p = 0.28). Ibandronate demonstrated a significant improvement of BMD in total femur, +1.3% versus -0.5% (p = 0.01) and in the ultradistal radius, +0.6% versus -1.9% (p = 0.039). Bone formation markers were reduced by ibandronate, whereas the bone resorption marker, NTX, was reduced in both groups. Calcium and calcitriol supplementation alone showed an excellent efficacy and safety profile, virtually maintaining BMD without any loss over 12 months after renal transplantation, whereas adding ibandronate significantly improved BMD in total femur and ultradistal radius, and also suppressed biomarkers of bone turnover. Ibandronate was also well tolerated.

Vascular calcifications and renal osteodystrophy in chronic hemodialysis patients: what is the relationship between them?

INTRODUCTION

Vascular calcifications (VCs) and renal osteodystrophy (ROD) are frequently seen together and represent the major causes of morbidity and mortality in hemodialysis (HD) patients. Some studies suggest a pathogenic link between them, but there is no consensus as yet regarding this issue. The main objective of our study was to establish whether there is any relation between VCs and ROD in our HD patients. We evaluated the prevalence of VCs and ROD and the relationship between VCs and some clinical and biochemical characteristics of HD patients.

METHODS

We examined radiological signs of VCs and ROD on hands and pelvis bone radiographs in 81 chronic HD patients, and we calculated a VC score on this basis.

RESULTS

We found a significant relation between radiological signs of ROD and those of VC (P = 0.019). The patients with ROD had a higher mean VC score (P = 0.02). By linear regression, the VC score correlated directly with serum calcium (Ca), phosphorus (P), intact parathyroid hormone (iPTH) and CaxP product and inversely with serum albumin. The logistic regression model revealed that ROD, male gender and treatment with calcium salts were predictive of VCs development. There were no associations between VCs and age, HD vintage, diabetes, dialysate Ca concentration, vitamin D treatment, spKt/V, URR and C-reactive protein (CRP) levels.

CONCLUSION

There seems to be a pathogenetic link between bone and artery diseases in chronic HD patients. Both VCs and ROD have a high prevalence. ROD, male gender and treatment with calcium salts are risk factors for VCs.

Bone Mineral Density in Patients on Maintenance Hemodialysis and Effect of Chronic Hepatitis C Virus Infection

OBJECTIVE

To determine the prevalence of osteopenia and osteoporosis in HD patients at our center; to investigate whether HCV infection affects BMD in hemodialysis patients; to test for correlations between bone mineral density (BMD) and clinical and laboratory parameters in this population.

SUBJECTS AND METHODS

The study involved 76 end-stage renal disease patients. Forty-three (56.6%) patients were tested negative for anti-HCV antibodies and HCV-RNA. Thirty-three (43.4%) of them had positivity of anti-HCV antibodies and permanent or intermittent HCV-RNA positivity at least for two years. Mean HD duration was 86.4 months. Patients completed a standard questionnaire that listed age, sex, occupation, education level; cause of renal failure, smoking history, dialysis duration, and sports activities engaged in during life, and pathologic bone fractures. The women answered additional items about age at menarche, number of pregnancies and menopausal status. Each subject underwent a baseline physical examination, including measurement of body weight and height for calculation of body mass index. The results of laboratory tests that had been done at monthly visits in the previous year were retrospectively evaluated, and mean levels for the year were used for correlation testing. Bone mineral density was measured in the spine, femoral neck and forearm. Relationships between BMD values and chronic HCV infection, laboratory results and clinical parameters were analyzed.

RESULTS

In the 43 patients who were negative for anti-HCV antibodies and HCV-RNA, spine BMD testing showed osteopenia in 16 (37.2%) cases and osteoporosis in 7 (16.3%) cases. The corresponding values for the neck of the femur were 14 (32.6%) and 6 (14.0%), and for the forearm were 19 (44.2%) and 15 (34.9%). In the 33 anti-HCV antibodies and HCV-RNA positive patients; spine BMD testing showed osteopenia in 10 (30.3%) cases and osteoporosis in 7 (21.2%) cases. The corresponding values for the neck of the femur were 17 (51.5%) and 4 (12.1%), and for the forearm were 4 (12.1%) and 25 (75.8%). Bone mineral density decreased as dialysis duration increased (p<0.05). There was no statistical difference between BMD measurements of chronic HCV infection positive and negative group.

CONCLUSION

However the mean BMD values for all three sites in the 76 HD patients were low HCV infection may not be a risk factor for low BMD in this population.

Assessment of parathyroid glands in hemodialysis patients by using color Doppler sonography

The aim of this study was to assess the role of color and spectral Doppler ultrasound (CDU) in the evaluation of enlarged parathyroid glands in hemodialysis patients with secondary hyperparathyroidism. Fourteen hemodialysis patients with elevated intact parathyroid hormone (iPTH) levels were evaluated prospectively with CDU. The volume of each observed parathyroid gland and the spectral CDU data (velocities, resistance and pulsatility indices, systolic to diastolic ratio, and flow volume output (FVO)) were noted. The biochemical data (iPTH, calcium, phosphate levels), and CDU results were analyzed with the Spearman correlation test. Two patients were excluded, and 27 enlarged parathyroid glands were observed in 12 patients. The mean total volume of enlarged parathyroid glands per patient was 1.95 cm(3) (0.06-5.5 cm(3)). Arterial supply was demonstrated in 78% (21/27) of enlarged parathyroid glands. Mean total FVO of enlarged glands per patient was 238.5 ml/min (620-0 ml/min) and mean iPTH level was 1,477 pg/ml (643-3,132 pg/ml). The positive correlations of total volume (p = 0.022), iPTH (p = 0.024), and FVO (p = 0.022) were statistically significant. In secondary hyperparathyroidism, total volume of the visualized enlarged parathyroid glands and the total of FVOs per patient are positively correlated with iPTH levels which may help clinical management and follow-up of end-stage renal disease patients.

Osteopenia: a common aspect of Fabry disease. Predictors of bone mineral density

PURPOSE

We investigated the bone mineral status in patients with untreated Fabry disease (FD).

METHODS

Descriptive, cross-sectional study in 53 patients with FD investigating bone mineral density (BMD)/content (dual energy x-ray absorptiometry scan), bone metabolism (parathyroid hormone, osteocalcin, and insulin-like growth factor I), and renal function (ethylene diamine tetraacetic acid clearance).

RESULTS

Mean BMD z score at the lumbar spine and femoral neck were -0.05 +/- 1.46 SD and -0.37 +/- 1.02 SD, respectively. Approximately 50% had osteopenia in the hip or lumbar spine and additionally four had osteoporosis. Multivariate analysis including body weight, impaired renal function, and genotype overall explained 48% of the variance in lumbar spine BMD (P < 0.001), whereas body weight, impaired renal function, and menopausal status in the female population accounted for more than 50% of the variation in BMD of both the lumbar spine and femoral neck (both P < 0.001). Twenty percent of patients had hyperparathyroidism. Although the level of parathyroid hormone was significantly associated with impaired renal function, osteocalcin levels were significantly higher in patients with lumbar spine osteopenia or osteoporosis than in those with normal BMD.

CONCLUSIONS

Osteopenia was present in approximately 50% of patients with untreated FD. Whether BMD and bone metabolism will improve after enzyme replacement therapy remains to be established.

Osteomalacia and secondary hyperparathyroidism after kidney transplantation: Relationship to vitamin D deficiency

Secondary hyperparathyroidism is highly prevalent in patients with end-stage renal disease. After successful kidney transplantation, however, parathyroid glands gradually involute to normal size with subsequent normalization of intact parathyroid hormone (PTH), serum calcium, and phosphorous concentrations. This report describes a 48-year-old diabetic end-stage renal disease patient who underwent a successful cadaveric kidney transplant. Serum calcium and phosphorous concentrations normalized within 6 months. Three years later, he presented with complaints of proximal muscle weakness that was progressively worsening. Physical examination revealed temporal wasting and proximal muscle weakness. Detailed neurologic examination was unremarkable except for decreased vibratory sensation in both feet. Laboratory data showed stable allograft function (serum creatinine, 1.3 mg/dL), hypocalcemia, and hypophosphatemia with markedly elevated alkaline phosphatase level (726 IU/L) and intact PTH level (947 pg/mL). Further laboratory evaluation revealed poor nutritional status and severe deficiency of 25(OH)D (4.0 ng/mL). Past medical history included remote episodes of acute pancreatitis due to prior alcohol abuse. Computed tomography of the abdomen showed calcific atrophic pancreas, and steatorrhea was confirmed on stool studies. Decreased bone mineral density was noted by computed tomography bone density scan. Secondary hyperparathyroidism and osteomalacia had developed due to severe vitamin D deficiency, occurring as a result of previously unrecognized, minimally symptomatic pancreatic exocrine insufficiency. Treatment with vitamin D, calcium, and pancreatic enzyme replacement led to remarkable resolution of clinical symptoms and secondary hyperparathyroidism (intact PTH, 65 pg/mL after therapy) and resulted in significant improvement in bone mineralization. Factors associated with vitamin D deficiency in the chronic kidney disease and post-transplant patient population are reviewed.

[Dialysis-associated spondyloarthropathy. Case report and literature review]

Hemodialysis has considerably prolonged the life of patients suffering from terminal renal failure. However, long-term hemodialysis leads to new bone complications and spinal disorders such as destructive spondyloarthropathy (DSA). At the present time DSA is reported in 8% to 18% of the dialysed patients. Diagnosis is based on severe narrowing of the intervertebral disk, erosions and geodes of the adjacent vertebral plates simulating infectious spondylitis. Lesions progressively involve posterior joints and may lead to severe destruction of the spine. The pathogenesis of this syndrome is still unknown. Several factors have been implicated, including microcrystal deposition, amyloidosis, inflammatory and foreign body reactions and suggest that the pathogenesis of erosive spondyloarthropathies of hemodialysed patients is multifactorial. Spinal instability inducing myelopathy and radiculopathy were observed in 8% of the cases. Treatment must be accorded to the natural disease course and to the quality of the bone. We report the case of a chronic dialysed patient with destructive spondyloarthropathy involving the cervical and thoracic spine. Pathogenesis, radiological datas and therapeutic approach are discussed.

Multifactorial uptake of Tc-99m methylene diphosphonate in chronic renal failure

Soft-tissue calcifications are a frequent complication in patients with chronic renal failure. Numerous underlying factors are thought to favor their formation. A case is presented of a patient who was in end-stage renal failure, secondary to glomerulonephritis. A renal transplant had not been successful. She was on long-term dialysis and had suffered aluminum toxicity (positive desferrioxamine test). She complained of proximal myopathy and bone pain.

Imaging in dialysis spondyloarthropathy

Destructive spondyloarthropathy has recently been described in patients who undergo maintenance hemodialysis for chronic renal disease. The condition most frequently involves the lower segment of the cervical spine, although the craniocervical junction also may be affected. Although the pathogenesis of destructive spondyloarthropathy remains unclear, the disorder is thought to relate to a hemodialysis-associated amyloidosis. It appears that the disease correlates with the duration of hemodialysis, although it has been reported in patients with chronic renal insufficiency not associated with hemodialysis. Radiographic features simulate those of an infectious process, encompassing a range of abnormalities from superficial erosions to large bony defects. Computed tomography (CT) images reveal osteolytic areas, with bone sclerosis of adjacent vertebral endplates, and minimal osteophytosis. The intervertebral spaces appear narrow or obliterated. On magnetic resonance imaging (MRI), the disorder may show the imaging characteristics of spondylodiskitis. The absence of high signal intensity on T2-weighted images generally helps to eliminate the diagnosis of an infection. With progression of the disease, collapse of a vertebral body and spinal instability may occur. Severe complications of destructive spondyloarthropathy in long-term dialysis patients may include spinal cord compromise, necessitating surgical decompression, with or without spinal stabilization.

Dialysis bone disease

The bone disease associated with end-stage renal failure (ESRD) and treatment are complex and multifactorial, and has changed in both clinical and imaging features over the past three decades. Whereas previously features of vitamin D deficiency (rickets/osteomalacia) and intense, and prolonged, secondary hyperparathyroidism (bone resorption, osteosclerosis, metastatic calcification) predominated, these features are now rarely evident radiologically. This has occurred through the better understanding of vitamin D metabolism and improvements in therapeutic management. However, metastatic calcification in soft tissues and 'adynamic" bone continue to be problematic. New complications have developed as a consequence of treatment (dialysis and transplantation), including amyloid deposition, noninfective sponyloarthropathy, osteonecrosis, and osteopenia/osteoporosis). Radiographs remain the most widely used imaging technique in examining for skeletal disease in patients with ESRD on maintenance dialysis. Occasionally, more sophisticated imaging (CT, MRI, nuclear medicine scanning) are helpful (parathyroid tumor localization, differentiation between infection and amyloid deposition). Developments in quantitative methods to assess bone density enable the effects of ESRD and treatment to be studied and monitored. Technical developments in computed tomography (rapid, multislice scanning) allow quantitation and monitoring of metastatic cardiac calcification in patients on hemodialysis, which has relevance to prognosis.

Calcification of all four parathyroid glands in a hemodialysis patient with secondary hyperparathyroidism revealed by computerized tomography

This report describes the parathyroid scan, computerized tomography and histologic findings in a young female hemodialysis patient with severe secondary hyperparathyroidism. These findings included hyperplasia and calcification of all four parathyroid glands.

Peritoneal Dialysis Case Forum

Hypercalcemia in a Peritoneal Dialysis 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.