Idiopathic juvenile osteoporosis

Do patients with nephrotic syndrome have an increased risk of osteoporosis? A nationwide population-based retrospective cohort study in Taiwan

OBJECTIVES

To evaluate whether nephrotic syndrome (NS) and further corticosteroid (CS) use increase the risk of osteoporosis in Asian population during the period January 2000-December 2010.

DESIGN

Nationwide population-based retrospective cohort study.

SETTING

All healthcare facilities in Taiwan.

PARTICIPANTS

A total of 28 772 individuals were enrolled.

INTERVENTIONS

26 614 individuals with newly diagnosed NS between 2000 and 2010 were identified and included in out study. 26 614 individuals with no NS diagnosis prior to the index date were age matched as controls. Diagnosis of osteoporosis prior to the diagnosis of NS or the same index date was identified, age, sex and NS-associated comorbidities were adjusted.

PRIMARY OUTCOME MEASURE

To identify risk differences in developing osteoporosis among patients with a medical history of NS.

RESULTS

After adjusting for covariates, osteoporosis risk was found to be 3.279 times greater in the NS cohort than in the non-NS cohort, when measured over 11 years after NS diagnosis. Stratification revealed that age older than 18 years, congestive heart failure, hyperlipidaemia, chronic kidney disease, liver cirrhosis and NS-related disease including diabetes mellitus, hepatitis B infection, hepatitis C infection, lymphoma and hypothyroidism, increased the risk of osteoporosis in the NS cohort, compared with the non-NS cohort. Additionally, osteoporosis risk was significantly higher in NS patients with CS use (adjusted HR (aHR)=3.397). The risk of osteoporosis in NS patients was positively associated with risk of hip and vertebral fracture (aHR=2.130 and 2.268, respectively). A significant association exists between NS and subsequent risk for osteoporosis.

CONCLUSION

NS patients, particularly those treated with CS, should be evaluated for subsequent risk of osteoporosis.

Drug Treatment of Low Bone Mass and Other Bone Conditions in Pediatric Patients

Osteoporosis may affect young individuals, albeit infrequently. In childhood, bone mass increases, reaching its peak between the second and third decades; then, after a period of stability, it gradually declines. Several conditions, including genetic disorders, chronic diseases, and some medications, can have an impact on bone homeostasis. Diagnosis in young patients is based on the criteria defined by the International Society for Clinical Densitometry (ISCD), published in 2013. High risk factors should be identified and monitored. Often simple interventions aimed to eliminate the underlying cause, to minimize the negative bone effects linked to drugs, or to increase calcium and vitamin D intake can protect bone mass. However, in selected cases, pharmacological treatment should be considered. Bisphosphonates remain the main therapeutic agent for children with significant skeletal fragility and are also useful in a large number of other bone conditions. Denosumab, an anti-RANKL antibody, could become a potential alternative treatment. Clinical trials to evaluate the long-term effects and safety of denosumab in children are ongoing.

It starts from the womb: maximizing bone health

The foundation of bone health is established in utero. Bone accrual starts from the developing fetus and continues throughout childhood and adolescence. This process is crucial to achieve peak bone mass. Understanding factors that influence bone accrual before attainment of peak bone mass is thus critical to improve bone health and prevent osteoporosis, thereby reducing the burden of osteoporotic fractures in older women. In this review, we broadly outline factors influencing peak bone mass from pregnancy to infancy, childhood and adolescence with potential diseases and medications that may affect the optimum trajectory to maximizing bone health. It is estimated that a 10% increase in peak bone mass will delay the onset of osteoporosis by 13 years in a woman.

New Insights Into Monogenic Causes of Osteoporosis

Osteoporosis, characterized by deteriorated bone microarchitecture and low bone mineral density, is a chronic skeletal disease with high worldwide prevalence. Osteoporosis related to aging is the most common form and causes significant morbidity and mortality. Rare, monogenic forms of osteoporosis have their onset usually in childhood or young adulthood and have specific phenotypic features and clinical course depending on the underlying cause. The most common form is osteogenesis imperfecta linked to mutations in COL1A1 and COL1A2, the two genes encoding type I collagen. However, in the past years, remarkable advancements in bone research have expanded our understanding of the intricacies behind bone metabolism and identified novel molecular mechanisms contributing to skeletal health and disease. Especially high-throughput sequencing techniques have made family-based studies an efficient way to identify single genes causative of rare monogenic forms of osteoporosis and these have yielded several novel genes that encode proteins partaking in type I collagen modification or regulating bone cell function directly. New forms of monogenic osteoporosis, such as autosomal dominant osteoporosis caused by WNT1 mutations or X-linked osteoporosis due to PLS3 mutations, have revealed previously unidentified bone-regulating proteins and clarified specific roles of bone cells, expanded our understanding of possible inheritance mechanisms and paces of disease progression, and highlighted the potential of monogenic bone diseases to extend beyond the skeletal tissue. The novel gene discoveries have introduced new challenges to the classification and diagnosis of monogenic osteoporosis, but also provided promising new molecular targets for development of pharmacotherapies. In this article we give an overview of the recent discoveries in the area of monogenic forms of osteoporosis, describing the key cellular mechanisms leading to skeletal fragility, the major recent research findings and the essential challenges and avenues in future diagnostics and treatments.

PLS3 Deletions Lead to Severe Spinal Osteoporosis and Disturbed Bone Matrix Mineralization

Mutations in the PLS3 gene, encoding Plastin 3, were described in 2013 as a cause for X-linked primary bone fragility in children. The specific role of PLS3 in bone metabolism remains inadequately understood. Here we describe for the first time PLS3 deletions as the underlying cause for childhood-onset primary osteoporosis in 3 boys from 2 families. We carried out thorough clinical, radiological, and bone tissue analyses to explore the consequences of these deletions and to further elucidate the role of PLS3 in bone homeostasis. In family 1, the 2 affected brothers had a deletion of exons 4-16 (NM_005032) in PLS3, inherited from their healthy mother. In family 2, the index patient had a deletion involving the entire PLS3 gene (exons 1-16), inherited from his mother who had osteoporosis. The 3 patients presented in early childhood with severe spinal compression fractures involving all vertebral bodies. The 2 brothers in family 1 also displayed subtle dysmorphic facial features and both had developed a myopathic gait. Extensive analyses of a transiliac bone biopsy from 1 patient showed a prominent increase in osteoid volume, osteoid thickness, and in mineralizing lag time. Results from quantitative backscattered electron imaging and Raman microspectroscopy showed a significant hypomineralization of the bone. Together our results indicate that PLS3 deletions lead to severe childhood-onset osteoporosis resulting from defective bone matrix mineralization, suggesting a specific role for PLS3 in the mineralization process. © 2017 American Society for Bone and Mineral Research.

New Genetic Forms of Childhood-Onset Primary Osteoporosis

Recent developments in genetic technology have given us the opportunity to look at diseases in a new and more detailed way. This Mini Review discusses monogenetic forms of childhood-onset primary osteoporosis, with the main focus on osteoporosis caused by mutations in WNT1 and PLS3, two of the most recently discovered genes underlying early-onset osteoporosis. The importance of WNT1 in the accrual and maintenance of bone mass through activation of canonical WNT signaling was recognized in 2013. WNT1 was shown to be a key ligand for the WNT-signaling pathway, which is of major importance in the regulation of bone formation. More recently, mutations in PLS3, located on the X chromosome, were shown to be the cause of X-linked childhood-onset primary osteoporosis affecting mainly males. The function of PLS3 in bone metabolism is still not completely understood, but it has been speculated to have an important role in mechanosensing by osteocytes and in matrix mineralization. In this new era of genetics, our knowledge on genetic causes of childhood-onset osteoporosis expands constantly. These discoveries bring new possibilities, but also new challenges. Guidelines are needed to implement this new genetic knowledge to clinical patient care and to guide genetic investigations in affected families.

Rare causes of osteoporosis

Osteoporosis is a metabolic bone disease characterized by loss of bone mass and strength, resulting in increased risk of fractures. It is classically divided into primary (post-menopausal or senile), secondary and idiopathic forms. There are many rare diseases, that cause directly or indirectly osteoporosis. The identification and classification of most of these rare causes of osteoporosis is crucial for the specialists in endocrinology and not, in order to prevent this bone complication and to provide for an early therapy. Several pathogenic mechanisms are involved, including various aspects of bone metabolism such as: decreased bone formation, increased bone resorption, altered calcium, phosphorus and/or vitamin D homeostasis, and abnormal collagen synthesis. In this review, less common forms of primary and secondary osteoporosis are described, specifying, if applicable: genetic causes, epidemiology, clinical features, and pathogenic mechanisms causing osteoporosis. A greater awareness of all rare causes of osteoporosis could reduce the number of cases classified as idiopathic osteoporosis and allow the introduction of appropriate and timely treatments.

Idiopathic juvenile osteoporosis: A case report and review of the literature

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Absence of family history of pediatric or adolescent osteoporosis.

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Presence of osseous osteoporosis on radiography.

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Absence of collagen defect on skin biopsy.

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No other identifiable causes of bone loss.

Introduction

Idiopathic Juvenile Osteoporosis is an uncommon condition that has few case reports in the literature. Reported series indicate that it is a condition classically accompanying vertebral and metaphyseal fractures during the immediate pre-puberty years but that seems to develop naturally during puberty. Current clinical treatment is complicated because of lack of understanding on the origins of Idiopathic Juvenile Osteoporosis.

Presentation of case

The 13-year-old female patient with no former complaints had pain in her left hip while walking 2 years ago. Excluding the secondary osteoporosis reasons, the patient was diagnosed with Idiopathic Juvenile Osteoporosis and after the medical treatment she was followed-up.

Discussion

The patient was subjected to a rehabilitation program for muscle weakness. She had difficulty in walking as a result of prolonged immobilization. At the end of a two-year treatment, significant improvement was achieved in muscle strength in the extremities, walking distance, and posture.

Conclusion

With this report, we would like to raise awareness about a possible association of persistent fractures with this rare metabolic disorder, Idiopathic Juvenile Osteoporosis, which should be included in differential diagnosis of patients with persistent appendicular skeleton fractures.

The ever-expanding conundrum of primary osteoporosis: aetiopathogenesis, diagnosis, and treatment

In recent years, as knowledge regarding the etiopathogenetic mechanisms of bone involvement characterizing many diseases has increased and diagnostic techniques evaluating bone health have progressively improved, the problem of low bone mass/quality in children and adolescents has attracted more and more attention, and the body evidence that there are groups of children who may be at risk of osteoporosis has grown. This interest is linked to an increased understanding that a higher peak bone mass (PBM) may be one of the most important determinants affecting the age of onset of osteoporosis in adulthood. This review provides an updated picture of bone pathophysiology and characteristics in children and adolescents with paediatric osteoporosis, taking into account the major causes of primary osteoporosis (PO) and evaluating the major aspects of bone densitometry in these patients. Finally, some options for the treatment of PO will be briefly discussed.

Juvenile osteoporosis in a 5-year-old girl

Idiopathic juvenile osteoporosis (IJO) is a term used to describe a primary osteoporosis of unknown etiology in prepubertal children. It is rarely described in the literature and treatment modalities vary with spontaneous remission also being reported at the time of puberty. We report a 5-year-old girl with IJO who had spinal deformities and was successfully treated with oral alendronate.

Pamidronate treatment stimulates the onset of recovery phase reducing fracture rate and skeletal deformities in patients with idiopathic juvenile osteoporosis: comparison with untreated patients

Although spontaneous remission occurs in patients with idiopathic juvenile osteoporosis (IJO), permanent bone deformities may occur. The effects of long-term pamidronate treatment on clinical findings, bone mineral status, and fracture rate were evaluated. Nine patients (age 9.8 ± 1.1 years, 7 males) with IJO were randomized to intravenous pamidronate (0.8 ± 0.1 mg/kg per day for 3 days; cycles per year 2.0 ± 0.1; duration 7.3 ± 1.1 years; n = 5) or no treatment (n = 4). Fracture rate, phalangeal quantitative ultrasound, and lumbar bone mineral density (BMD) by dual energy X-ray absorptiometry at entry and during follow-up (range 6.3-9.4 years) were assessed. Bone pain improved in treated patients. Difficulty walking continued for 3-5 years in untreated patients, and vertebral collapses occurred in three of them. During follow-up, phalangeal amplitude-dependent speed of sound (AD-SoS), bone transmission time (BTT), and lumbar BMDarea and BMDvolume progressively increased in treated patients (P < 0.05-P < 0.0001). In untreated patients AD-SoS and BTT decreased during the first 2-4 years of follow-up (P < 0.05-P < 0.01); lumbar BMDarea increased after 6 years (P < 0.001) whereas BTT and lumbar BMDvolume increased after 7 years of follow-up (P < 0.05 and P < 0.001, respectively). At the end of follow-up, AD-SoS, BTT, lumbar BMDarea, and BMDvolume Z-scores were lower in untreated patients than in treated patients (-2.2 ± 0.3 and -0.5 ± 0.2; -1.9 ± 0.2 and -0.6 ± 0.2; -2.3 ± 0.3 and -0.7 ± 0.3; -2.4 ± 0.2 and -0.7 ± 0.3, P < 0.0001, respectively). Fracture rate was higher in untreated patients than in treated patients during the first 3 years of follow-up (P < 0.02). Our study showed that spontaneous recovery of bone mineral status is unsatisfactory in patients with IJO. Pamidronate treatment stimulated the onset of recovery phase reducing fracture rate and permanent disabilities without evidence of side-effects.

Low bone mass in children and adolescents

Osteoporosis is a disease characterized by low bone mass and micro architectural alterations of bone tissue leading to enhanced bone fragility and increased fracture risk. Although research in osteoporosis has focused mainly on the role of bone loss in the elderly population, it is becoming increasingly clear that the amount of bone that is gained during growth is also an important determinant of future resistance to fractures. Thus, considerable interest is being placed on defining preventive strategies that optimize the gain of bone mass during childhood and adolescence. Knowledge of the determinants accounting for the physiologic and genetic variations in bone accumulation in children will provide the best means toward the early diagnosis and treatment of osteoporosis. This article reviews the techniques available for bone mass measurements in children and the major determinants and diseases influencing bone accretion during childhood and adolescence.

How to manage osteoporosis in children

Osteoporosis is increasingly being seen in young people. The primitive forms are relatively rare, but the secondary forms--particularly in long-term corticosteroid therapy--are a relevant problem given the much longer survival in chronic diseases such as cystic fibrosis, chronic renal insufficiency, leukaemia, and Duchenne muscular dystrophy. Controlled, prospective studies to evaluate the results of prevention and therapy in children are still lacking. The basis of therapy is the correct daily intake of calcium and the use of vitamin D (or active metabolites). This helps the growing skeleton to restore its equilibrium in many cases. Restraining the long-term use of corticosteroids to the minimum effective dose and shorter duration is essential. In severe cases, particularly in the presence of fractures, bisphosphonates can be remarkably effective. In some cases, such as idiopathic juvenile osteoporosis, the rule is spontaneous resolution, and the advisability of an aggressive drug therapy is discussed.

Osteoporosis in children and adolescents: etiology and management

Bone mass increases progressively during childhood, but mainly during adolescence when approximately 40% of total bone mass is accumulated. Peak bone mass is reached in late adolescence, and is a well recognised risk factor for osteoporosis later in life. Thus, increasing peak bone mass can prevent osteoporosis. The critical interpretation of bone mass measurements is a crucial factor for the diagnosis of osteopenia/osteoporosis in children and adolescents. To date, there are insufficient data to formally define osteopenia/osteoporosis in this patient group, and the guidelines used for adult patients are not applicable. In males and females aged <20 years the terminology 'low bone density for chronologic age' may be used if the Z-score is less than -2. For children and adolescents, this terminology is more appropriate than osteopenia/osteoporosis. Moreover, the T-score should not be used in children and adolescents. Many disorders, by various mechanisms, may affect the acquisition of bone mass during childhood and adolescence. Indeed, the number of disorders that have been identified as affecting bone mass in this age group is increasing as a consequence of the wide use of bone mass measurements. The increased survival of children and adolescents with chronic diseases or malignancies, as well as the use of some treatment regimens has resulted in an increase in the incidence of reduced bone mass in this age group. Experience in treating the various disorders associated with osteoporosis in childhood is limited at present. The first approach to osteoporosis management in children and adolescents should be aimed at treating the underlying disease. The use of bisphosphonates in children and adolescents with osteoporosis is increasing and their positive effect in improving bone mineral density is encouraging. Osteoporosis prevention is a key factor and it should begin in childhood. Pediatricians should have a fundamental role in the prevention of osteoporosis, suggesting strategies to achieve an optimal peak bone mass.

Osteoporosis and measurement of bone mass in children and adolescents

Osteoporosis increasingly is recognized as a pediatric concern. Fragility fractures occur in children and adolescents with genetic disorders and those with a variety of chronic diseases. Others may not fracture in childhood but reach adulthood with a reduced peak bone mass and increased lifelong risk of osteoporosis. This article reviews the indications for pediatric bone density testing, the strengths and limitations of densitometry methods, and the challenges of interpreting the results. The goals are to demystify the densitometry report and to clarify the role of bone density tests in assessing and managing skeletal health in children.

Effective parenteral clodronate treatment of a child with severe juvenile idiopathic osteoporosis

We report on an 8 years and 3 months old boy with severe idiopathic juvenile osteoporosis (IJO). Clinical features included multiple fractures, especially of the vertebrae, and neurological symptoms. Biological studies showed non-parathyroid hormone-mediated excessive bone resorption and massive urinary calcium loss. Although IJO is usually a self-limiting condition after puberty, the severity of our patient's manifestations required therapeutic intervention. Clodronate (dichloromethylene-bisphosphonate) was administered parenterally every 3 months for a period of 2 years. Dramatic clinical and biochemical improvement was noted within 2 weeks. All parameters of bone resorption normalised and no new fractures occurred. After 6 months of treatment, radiological improvement with healing of fractures and rebuilding of the vertebral plates was documented. Bone mineral density increased to normal within 1 year and growth velocity was accelerated. After 2 years, treatment was stopped at the age of 10 years and 3 months. One year later, back pain and increasing pain in the knee region recurred. A tibial fracture was evident and, again, bone mineral density was far below normal. Bisphosphonate medication was reinstituted leading to rapid improvement. No side-effects were observed.

CONCLUSION

Parenteral clodronate therapy is effective in managing severe idiopathic juvenile osteoporosis.

Osteoporosis in children and adolescent girls: case report of idiopathic juvenile osteoporosis and review of the literature

The diagnosis and treatment of osteoporosis is an important aspect of gynecologic training and practice. Idiopathic juvenile osteoporosis (IJO) is a rare disease of children and adolescents that resolves after the onset of puberty. A case report is presented and current methods of diagnosis and treatment of IJO are discussed as well as the differential diagnosis. A MEDLINE search was performed of the following terms: idiopathic juvenile osteoporosis, pediatric osteoporosis, adolescent osteoporosis, bisphosphonates pediatric adolescent, and pregnancy osteoporosis, and references from bibliographies of selected papers were used as well. All papers in English, French, and German are considered in this review. There were 114 papers selected as relevant to the topic. Data relevant to the diagnosis, pathogenesis, methods of imaging, laboratory evaluation, differential diagnosis, and treatment of IJO are presented. IJO is a diagnosis of exclusion in the pediatric and adolescent patient with osteoporosis. Although bone density gradually improves after the onset of puberty, treatment of currently affected children and adolescents involves activity restriction, calcium, vitamin D, and bisphosphonate therapy. Future reproductive concerns are discussed and areas requiring additional study are reviewed.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader will be able to describe the condition idiopathic juvenile osteoporosis, compare the clinical features of this condition to other similar conditions, outline the diagnostic workup of a child with this condition, and list the potential therapeutic options for a patient with idiopathic juvenile osteoporosis.

Osteoporosis in childhood: bone density of children in health and disease

Bone mineral density in later life largely depends on the peak bone mass achieved in adolescence or young adulthood. A reduced bone density is associated with increased fracture risk in adults as well as in children. Pediatricians should therefore play an important role in the early recognition and treatment of childhood osteoporosis. Juvenile idiopathic osteoporosis and osteogenesis imperfecta are examples of primary osteoporosis in childhood. However, osteoporosis is more frequently a complication of a chronic disease or its treatment. This paper provides an overview of bone and bone metabolism in healthy children and the use of diagnostic tools, such as biochemical markers of bone turnover and several bone densitometry techniques. Furthermore, a number of diseases associated with osteoporosis in childhood and possible treatment strategies are discussed.

Osteoporosis in children and adolescents: diagnosis, risk factors, and prevention

Bone mass acquired during childhood and adolescence is a key determinant of adult bone health. Peak bone mass, which is achieved in late adolescence, is a main determinant of osteoporosis in adulthood. Therefore, any factor adversely impacting on bone acquisition during childhood or adolescence can potentially have long-standing detrimental effects on bone health predisposing to osteoporosis and fracture risk. Thus, osteoporosis can well have its origin in childhood and adolescence. Pediatricians should be playing an active role in osteoporosis diagnosis and prevention. It is increasingly recognized that osteoporosis may occur in some disorders of children and adolescents. In this paper we review the diagnostic criteria of osteopenia/osteoporosis by densitometric assessment of bone mineral density, the contributing factors, and the mechanisms whereby several disorders may affect the acquisition of bone mass in children and adolescents. Finally, some recommendations to optimize peak bone mass in order to prevent osteopenia/osteoporosis are suggested.