Renal osteodystrophy: a pediatric perspective, 2005

Bone Disorders in Pediatric Chronic Kidney Disease: A Literature Review

Intense changes in mineral and bone metabolism are frequent in chronic kidney disease (CKD) and represent an important cause of morbidity and reduced quality of life. These disorders have conventionally been defined as renal osteodystrophy and classified based on bone biopsy, but due to a lack of bone biopsy data and validated radiological methods to evaluate bone morphology in children, it has been challenging to effectively assess renal osteodystrophy in pediatric CKD; the consequence has been the suboptimal management of bone disorders in children. CKD-mineral and bone disorder (CKD-MBD) is a new expression used to describe a systemic disorder of mineral and bone metabolism as a result of CKD. CKD-MBD is a triad of biochemical imbalances in calcium, phosphate, parathyroid hormone, and vitamin D; bone deformities and soft tissue calcification. This literature review aims to explore the pathogenesis, diagnostic approach, and treatment of CKD-MBD in children and the effects of renal osteodystrophy on growing skeleton, with a specific focus on the biological basis of this peculiar condition.

Complete heart block in a boy with hyperostosis–hyperphosphataemia syndrome: a case report

Background

Hyperostosis–hyperphosphataemia syndrome (HHS) is a rare metabolic disorder characterized by recurrent painful swelling of long bones and periosteal new bone formation.

Case summary

A 6-year-old boy was referred to our centre due to bradycardia. He was diagnosed with HHS 3 years’ prior, after investigation for the cause of joint pain and genu valgum. During medical follow-up in 2013–16, the paediatric cardiologist discovered thickened and calcified mitral and aortic valves and progression of cardiac conduction disturbance from 1st degree to 3rd degree atrioventricular block (AVB). The patient died in 2017 due to multiorgan failure caused by hyperphosphataemia and ectopic calcification.

Discussion

Our case is unique in that ectopic calcification occurred in the aortic, mitral valve and cardiac conduction system, and AVB progressed from 1st degree to 3rd degree over time despite treatment with high-dose phosphate binders.

Correction of lower limb deformities in children with renal osteodystrophy by guided growth technique

PURPOSE

Renal osteodystrophy (ROD) may cause severe lower limb deformities in children. The purpose of this study is to evaluate the efficacy of the temporary hemiepiphysiodesis for the correction of lower limb deformities in children with ROD.

METHODS

Guided growth correction by hemiepiphysiodesis has been performed in skeletally immature patients with deformities of the lower limbs caused by ROD. The correction of the mechanical axes of the lower limbs and its correction speed have been evaluated.

RESULTS

A total of seven patients with ROD, five males and two females, were treated with the above technique. The average age of the patients at their first surgery was 7.8 years (2.9 to 13.6). The average follow-up time 5.2 years (2.3 to 8). There were 13 valgus deformities and one varus deformity of the knee. The measure of the lower limb angular deformity was in the range of 10° to 47°. Restoration of normal mechanical axis was achieved in all patients at the final follow-up. Three patients relapsed and required further hemiepiphysiodesis. The average time for correction was 20 months (7 to 30). The average speed of correction was 0.49° per month for a tibia and 1.73° per month for a femur. There were two minor complications: a screw mobilisation and a screw breakage occurred during removal.

CONCLUSION

Guided growth technique by hemiepiphysiodesis is a mini-invasive surgical procedure that has been found to be effective for the correction of misalignment due to ROD in skeletally immature patients. The method has allowed progressive correction of the deformities at any age in childhood. These patients are predisposed to relapse to their deformities, thus a strict follow-up is required.

[Short stature in chronic kidney disease: physiopathology and treatment with growth hormone]

Growth failure is frequent and a clinically important issue in children with chronic kidney disease (CKD). Many factors contribute to impaired growth in these children, including abnormalities in the growth hormone (GH)--insulin-like growth factor 1 (IGF-1) axis, malnutrition, acidosis, renal bone disease and glucocorticoid associated treatment. The management of growth failure in children with CKD is complicated by the presence of other-disease related complications requiring medical intervention. Despite evidence of GH efficacy and safety in this population, this therapy is still underutilized. This review shows the impact, the causes and the treatment of growth failure in children with CKD.

Correction of lower limb deformities in children with renal osteodystrophy by the Ilizarov method

BACKGROUND

Children with renal osteodystrophy (ROD) may develop severe angular deformities of the limbs. Various methods, both medical and surgical, have been described for correction of these deformities, but a literature search showed only 1 child previously treated by the Ilizarov method. The purpose of this study was to characterize the deformities found in our group of patients and to describe our experience in treating these patients with the Ilizarov method.

METHODS

Correction of angular deformity by the Ilizarov method was performed on 8 limb segments in 5 patients with ROD. Mean age was 14.9 years. Two patients were on hemodialysis, and 3 had functioning kidney grafts. Surgery was deferred until stabilization of metabolic parameters.

RESULTS

There was 1 varus and 7 valgus deformities. Preoperative coronal deformity averaged 29 degrees (18-38 degrees). The Ilizarov apparatus was used in all cases. Correction time averaged 23 days (20-28 days). The time from completion of correction to frame removal averaged 71 days (48-113 days). There were no changes in metabolic parameters or frequency of hemodialysis throughout the treatment. Restoration of a normal mechanical axis was achieved in 4 of the 5 patients. One case failed due to intraarticular instability. There were no major complications. Minor complications included pin tract infections, which responded to antibiotic treatment, and premature consolidation in 1 case. Follow-up averaged 6.5 years (1-10 years). The alignment obtained at surgery was maintained in all 4 patients, and they are functional and symptom-free. The patient for whom the surgery failed remains wheelchair-bound.

CONCLUSIONS

The Ilizarov method was found to be safe and effective for correction of malalignment due to ROD. Optimization of metabolic parameters is essential before surgery and throughout correction. The procedure is contraindicated in patients with significant intraarticular knee pathology.

Growth in children with chronic renal failure and after renal transplantation

Growth retardation is a major problem for many children with chronic renal failure (CRF) and transplantation. The aim of this study is to assess the relation between height, glomerular filtration rate (GFR), hormonal alterations in children with CRF on regular haemodialysis (HD), and the impact of functioning graft after kidney transplantation.Thirty-six hemodialysed children were included in the study beside 32 pediatric transplants. Mean duration on HD was 14.72 +/- 7.73 months for the CRF group, while the mean interval after transplantation was 1.97 +/- 0.9 years for the second group. Moreover, twenty healthy children of matched age and sex served as controls. Assessment of growth parameters included height, expressed as standard deviation scores (Ht SDS) for chronological age, serum levels of growth hormone (hGH), and parathormone (PTH). Growth performance was evaluated twice: at the start of the study and one year later. Children with CRF and transplantation had significantly higher levels of both serum hGH and PTH compared to their controls, while CRF children experienced significantly higher serum levels of both hGH and PTH compared to those with functioning graft. Furthermore, analysis of our results by non-parametric Kendall's correlation at the start and one year later revealed negative correlation concerning dialysis duration, serum creatinine, and PTH. On the other hand, positive correlation was achieved for serum calcium and GFR.

Cranial nerve palsies in renal osteodystrophy

There is a wide differential diagnosis for patients presenting with multiple cranial nerve palsies, including infectious, inflammatory, malignant, genetic, toxic, and metabolic conditions. This report describes the clinical features, neuroimaging findings, and response to surgical treatment in a patient with bilateral deafness and recurrent episodes of bilateral facial nerve palsy that were caused by renal osteodystrophy. It is suggested that renal osteodystrophy be considered in the differential diagnosis of multiple cranial nerve palsies in the appropriate clinical setting.

Renal osteodystrophy in children: a systemic disease associated with cardiovascular manifestations

The increasing prevalence of chronic kidney disease (CKD) in the United States demands a closer evaluation of and attention to associated morbidities, and, particularly, the rising mortality related to cardiovascular disease in all age groups. Patients with CKD demonstrate an increased risk of coronary artery disease due to calcium deposition and subsequent arterial stiffening, in addition to left ventricular dysfunction with associated heart failure and arrhythmias. While clearly impacted by the traditional risk factors for development of cardiovascular disease (CVD), patients with CKD are also affected by non-traditional risk factors, including calcium overloading related to aggressive management of secondary hyperparathyroidism. Recent data have shown that a substantial number of patients with CKD are deficient in vitamin D on a nutritional basis, in addition to the known decrease in the kidney-produced active metabolite during progressive CKD. Historically, vitamin D has been described as an endocrine hormone that regulates blood calcium and parathyroid hormone levels. It has become increasingly clear, through the recognition of a vitamin D receptor in most tissues, that vitamin D possesses functions well beyond calcium homeostasis, such that a deficiency may contribute to the development of CVD. In this brief review, the role of vitamin D activation through its vitamin D receptor will serve as an introduction to the magnitude of the nutritional deficits in children, adults, and those with CKD. As therapeutic entities in the management of renal osteodystrophy, vitamin D analogues play an important role in cardiovascular health that continues to evolve. Preliminary studies indicate that vitamin D therapy for control of secondary hyperparathyroidism may confer cardioprotection and reduce mortality. Attention to care of osteodystrophy in CKD must take into account heart health as well.