Recommendations for the diagnosis and management of Fabry disease in pediatric patients: a document from the Rare Diseases Committee of the Brazilian Society of Nephrology (Comdora-SBN) / Recomendações para o diagnóstico e manejo de pacientes pediátricos com doença de Fabry: documento do comitê de doenças raras da Sociedade Brasileira de Nefrologia (Comdora-SBN)

Fabry disease (FD) is a genetic disease, with X-chromosome linked inheritance, due to variants in the GLA gene that encodes the α-galactosidase A (α-GAL) enzyme. The purpose of the present study was to create a consensus aiming to standardize the recommendations regarding the renal involvement of FD with guidelines on the diagnosis, screening, and treatment of pediatric patients. This consensus is an initiative of the Rare Diseases Committee (Comdora) of the Brazilian Society of Nephrology (SBN). Randomized controlled clinical studies and studies with real-life data added to the authors' experience were considered for this review. The result of this consensus was to help manage patient and physician expectations regarding treatment outcomes. Thus, this consensus document recommends the investigation of the pediatric family members of an index case, as well as cases with suggestive clinical signs. From the diagnosis, assess all possible FD impairments and grade through scales. From an extensive review of the literature including pediatric protocols and particularly evaluating pediatric cases from general studies, it can be concluded that the benefits of early treatment are great, especially in terms of neuropathic pain and renal impairment parameters and outweigh the possible adverse effects that were mainly manifested by infusion reactions.

A doença de Fabry (DF) é uma doença genética, com herança ligada ao cromossomo X, devido a variantes no gene GLA que codifica a enzima α-galactosidase A (α-GAL). O propósito do presente estudo foi criar um consenso objetivando padronizar as recomendações em relação ao acometimento renal da DF com orientações sobre o diagnóstico, rastreamento, e tratamento de pacientes pediátricos. Esse consenso é uma iniciativa do Comitê de Doenças Raras (Comdora) da Sociedade Brasileira de Nefrologia (SBN). Foram considerados para esta revisão estudos clínicos controlados randomizados e estudos com dados de vida real somados à experiência dos autores. O resultado desse consenso foi auxiliar no gerenciamento das expectativas de pacientes e médicos quanto aos resultados do tratamento. Assim, este documento de consenso recomenda a investigação dos familiares pediátricos de um caso índice, assim como de casos com clínica sugestiva. A partir do diagnóstico, avaliar todos os possíveis acometimentos da DF e graduar através de escalas. A partir de uma revisão extensa da literatura incluindo protocolos pediátricos e avaliando particularmente os casos pediátricos de estudos gerais, pode-se concluir que os benefícios do tratamento precoce são grandes, principalmente quanto aos parâmetros de dor neuropática e do acometimento renal, e suplantam os possíveis adversos que foram sobretudo manifestados por reações infusionais.

Brazilian consensus recommendations for the diagnosis, screening, and treatment of individuals with fabry disease: Committee for Rare Diseases - Brazilian Society of Nephrology/2021 / Consenso brasileiro de doença de fabry: recomendações de diagnóstico, triagem e tratamento. Comitê de doenças raras (Comdora) - SBN/2021

Abstract Fabry disease (FD) is an X-linked inherited disorder caused by mutations in the GLA gene encoding enzyme alpha-galactosidase A (α-Gal A). The purpose of this study was to produce a consensus statement to standardize the recommendations concerning kidney involvement in FD and provide advice on the diagnosis, screening, and treatment of adult and pediatric patients. This consensus document was organized from an initiative led by the Committee for Rare Diseases (Comdora) of the Brazilian Society of Nephrology (SBN). The review considered randomized clinical trials, real-world data studies, and the expertise of its authors. The purpose of this consensus statement is to help manage patient and physician expectations concerning the outcomes of treatment. Our recommendations must be interpreted within the context of available evidence. The decisions pertaining to each individual case must be made with the involvement of patients and their families and take into account not only the potential cost of treatment, but also concurrent conditions and personal preferences. The Comdora intends to update these recommendations regularly so as to reflect recent literature evidence, real-world data, and appreciate the professional experience of those involved. This consensus document establishes clear criteria for the diagnosis of FD and for when to start or stop specific therapies or adjuvant measures, to thus advise the medical community and standardize clinical practice.

Resumo A doença de Fabry (DF) é uma doença genética, com herança ligada ao cromossomo X, que ocorre devido a variantes no gene GLA que codifica a enzima α-galactosidase A (α-GAL). O propósito do presente estudo foi criar um consenso objetivando padronizar as recomendações em relação ao acometimento renal da DF com orientações sobre o diagnóstico, rastreamento e tratamento de pacientes adultos e pediátricos. Esse consenso é uma iniciativa do Comitê de Doenças Raras (Comdora) da Sociedade Brasileira de Nefrologia (SBN). Foram considerados para esta revisão estudos clínicos controlados randomizados e estudos com dados de vida real somado à experiência dos autores. O resultado desse consenso foi auxiliar no gerenciamento das expectativas de pacientes e médicos quanto aos resultados do tratamento. Nossas recomendações devem ser interpretadas no contexto das evidências e ressaltando que as decisões finais devem ser tomadas individualmente, em uma decisão conjunta com o paciente e familiares, considerando os custos envolvidos, não apenas financeiros, doenças concomitantes e preferências pessoais. O Comdora pretende atualizar essas recomendações regularmente, e assim seguir novas evidências na literatura, considerar dados de vida real e valorizar a experiência profissional dos envolvidos. Esse consenso estabelece critérios claros para o diagnóstico da DF, início e interrupção de terapia específica e de medidas adjuntas, orientando a comunidade médica e uniformizando condutas.

Recommendations for the diagnosis and management of Fabry disease in pediatric patients: a document from the Rare Diseases Committee of the Brazilian Society of Nephrology (Comdora-SBN).

Fabry disease (FD) is a genetic disease, with X-chromosome linked inheritance, due to variants in the GLA gene that encodes the α-galactosidase A (α-GAL) enzyme. The purpose of the present study was to create a consensus aiming to standardize the recommendations regarding the renal involvement of FD with guidelines on the diagnosis, screening, and treatment of pediatric patients. This consensus is an initiative of the Rare Diseases Committee (Comdora) of the Brazilian Society of Nephrology (SBN). Randomized controlled clinical studies and studies with real-life data added to the authors' experience were considered for this review. The result of this consensus was to help manage patient and physician expectations regarding treatment outcomes. Thus, this consensus document recommends the investigation of the pediatric family members of an index case, as well as cases with suggestive clinical signs. From the diagnosis, assess all possible FD impairments and grade through scales. From an extensive review of the literature including pediatric protocols and particularly evaluating pediatric cases from general studies, it can be concluded that the benefits of early treatment are great, especially in terms of neuropathic pain and renal impairment parameters and outweigh the possible adverse effects that were mainly manifested by infusion reactions.

Brazilian consensus recommendations for the diagnosis, screening, and treatment of individuals with fabry disease: Committee for Rare Diseases - Brazilian Society of Nephrology/2021.

Fabry disease (FD) is an X-linked inherited disorder caused by mutations in the GLA gene encoding enzyme alpha-galactosidase A (α-Gal A). The purpose of this study was to produce a consensus statement to standardize the recommendations concerning kidney involvement in FD and provide advice on the diagnosis, screening, and treatment of adult and pediatric patients. This consensus document was organized from an initiative led by the Committee for Rare Diseases (Comdora) of the Brazilian Society of Nephrology (SBN). The review considered randomized clinical trials, real-world data studies, and the expertise of its authors. The purpose of this consensus statement is to help manage patient and physician expectations concerning the outcomes of treatment. Our recommendations must be interpreted within the context of available evidence. The decisions pertaining to each individual case must be made with the involvement of patients and their families and take into account not only the potential cost of treatment, but also concurrent conditions and personal preferences. The Comdora intends to update these recommendations regularly so as to reflect recent literature evidence, real-world data, and appreciate the professional experience of those involved. This consensus document establishes clear criteria for the diagnosis of FD and for when to start or stop specific therapies or adjuvant measures, to thus advise the medical community and standardize clinical practice.

Endothelial Microparticles in Uremia: Biomarkers and Potential Therapeutic Targets.

Endothelial microparticles (EMPs) are vesicles derived from cell membranes, which contain outsourced phosphatidylserine and express adhesion molecules, such as cadherin, intercellular cell adhesion molecule-1 (ICAM-1), E-selectin, and integrins. EMPs are expressed under physiological conditions and continue circulating in the plasma. However, in pathologic conditions their levels increase, and they assume a pro-inflammatory and pro-coagulant role via interactions with monocytes; these effects are related to the development of atherosclerosis. Chronic kidney dysfunction (CKD) characterizes this dysfunctional scenario through the accumulation of uremic solutes in the circulating plasma, whose toxicity is related to the development of cardiovascular diseases. Therefore, this review aims to discuss the formation of EMPs and their biological effects in the uremic environment. Data from previous research demonstrate that uremic toxins are closely associated with the activation of inflammatory biomarkers, cardiovascular dysfunction processes, and the release of EMPs. The impact of a decrease in circulating EMPs in clinical studies has not yet been evaluated. Thus, whether MPs are biochemical markers and/or therapeutic targets has yet to be established.

Bone biopsy in nephrology practice.

Renal osteodystrophy (ROD), a group of metabolic bone diseases secondary to chronic kidney disease (CKD), still represents a great challenge to nephrologists. Its management is tailored by the type of bone lesion - of high or low turnover - that cannot be accurately predicted by serum biomarkers of bone remodeling available in daily clinical practice, mainly parathyroid hormone (PTH) and alkaline phosphatase (AP). In view of this limitation, bone biopsy followed by bone quantitative histomorphometry, the gold-standard method for the diagnosis of ROD, is still considered of paramount importance. Bone biopsy has also been recommended for evaluation of osteoporosis in the CKD setting to help physicians choose the best anti-osteoporotic drug. Importantly, bone biopsy is the sole diagnostic method capable of providing dynamic information on bone metabolism. Trabecular and cortical bones may be analyzed separately by evaluating their structural and dynamic parameters, thickness and porosity, respectively. Deposition of metals, such as aluminum and iron, on bone may also be detected. Despite of these unique characteristics, the interest on bone biopsy has declined over the last years and there are currently few centers around the world specialized on bone histomorphometry. In this review, we will discuss the bone biopsy technique, its indications, and the main information it can provide. The interest on bone biopsy should be renewed and nephrologists should be capacitated to perform it as part of their training during medical residency.

Bone biopsy in nephrology practice / Biópsia óssea na prática nefrológica

Abstract Renal osteodystrophy (ROD), a group of metabolic bone diseases secondary to chronic kidney disease (CKD), still represents a great challenge to nephrologists. Its management is tailored by the type of bone lesion - of high or low turnover - that cannot be accurately predicted by serum biomarkers of bone remodeling available in daily clinical practice, mainly parathyroid hormone (PTH) and alkaline phosphatase (AP). In view of this limitation, bone biopsy followed by bone quantitative histomorphometry, the gold-standard method for the diagnosis of ROD, is still considered of paramount importance. Bone biopsy has also been recommended for evaluation of osteoporosis in the CKD setting to help physicians choose the best anti-osteoporotic drug. Importantly, bone biopsy is the sole diagnostic method capable of providing dynamic information on bone metabolism. Trabecular and cortical bones may be analyzed separately by evaluating their structural and dynamic parameters, thickness and porosity, respectively. Deposition of metals, such as aluminum and iron, on bone may also be detected. Despite of these unique characteristics, the interest on bone biopsy has declined over the last years and there are currently few centers around the world specialized on bone histomorphometry. In this review, we will discuss the bone biopsy technique, its indications, and the main information it can provide. The interest on bone biopsy should be renewed and nephrologists should be capacitated to perform it as part of their training during medical residency.

Resumo A osteodistrofia renal (OR), um grupo de doenças ósseas metabólicas secundárias à doença renal crônica (DRC), ainda representa um grande desafio para os nefrologistas. Seu manejo é individualizado de acordo com o tipo de lesão óssea - de alto ou baixo remodelamento - cujo diagnóstico não pode ser prevista com precisão pelos biomarcadores séricos de remodelação óssea disponíveis na prática clínica diária, principalmente o paratormônio (PTH) e a fosfatase alcalina (FA). Em vista dessa limitação, biópsia óssea seguida de histomorfometria óssea quantitativa, método padrão-ouro para o diagnóstico de OR, ainda é considerado um procedimento de grande importância. A biópsia óssea também é recomendada na avaliação da osteoporose em indivíduos com DRC, a fim de auxiliar na escolha do melhor medicamento anti-osteoporótico. É importante observar que a biópsia óssea é o único método diagnóstico capaz de proporcionar informações dinâmicas sobre o metabolismo ósseo. Os ossos trabecular e cortical podem ser analisados separadamente por meio da avaliação de seus parâmetros estruturais e dinâmicos, espessura e porosidade, respectivamente. A deposição óssea de metais como alumínio e ferro também pode ser detectada. Apesar de suas características singulares, o interesse pela biópsia óssea diminuiu nos últimos anos. Poucos centros em todo o mundo são especializados em histomorfometria óssea. A presente revisão discute a técnica de biópsia óssea, suas indicações e as principais informações que ela pode oferecer. O interesse pela biópsia óssea deve ser renovado e os nefrologistas devem ser capacitados a realizá-la durante o período de residência médica.

The impact of type 2 diabetes on bone metabolism.

Diabetes complications and osteoporotic fractures are two of the most important causes of morbidity and mortality in older patients and share many features including genetic susceptibility, molecular mechanisms, and environmental factors. Type 2 diabetes mellitus (T2DM) compromises bone microarchitecture by inducing abnormal bone cell function and matrix structure, with increased osteoblast apoptosis, diminished osteoblast differentiation, and enhanced osteoclast-mediated bone resorption. The linkage between these two chronic diseases creates a possibility that certain antidiabetic therapies may affect bone quality. Both glycemic and bone homeostasis are under control of common regulatory factors. These factors include insulin, accumulation of advanced glycation end products, peroxisome proliferator-activated receptor gamma, gastrointestinal hormones (such as the glucose-dependent insulinotropic peptide and the glucagon-like peptides 1 and 2), and bone-derived hormone osteocalcin. This background allows individual pharmacological targets for antidiabetic therapies to affect the bone quality due to their indirect effects on bone cell differentiation and bone remodeling process. Moreover, it's important to consider the fragility fractures as another diabetes complication and discuss more deeply about the requirement for adequate screening and preventive measures. This review aims to briefly explore the impact of T2DM on bone metabolic and mechanical proprieties and fracture risk.

Vildagliptin has the same safety profile as a sulfonylurea on bone metabolism and bone mineral density in post-menopausal women with type 2 diabetes: a randomized controlled trial.

BACKGROUND: Several antidiabetic therapies affect bone metabolism. Sulfonylureas have the lowest impact on bone among oral antidiabetics. The objective of this study is to compare the effects of vildagliptin and gliclazide modified release (MR) on bone turnover markers (BTMs) and bone mineral density (BMD) in postmenopausal women with uncontrolled type 2 diabetes (T2D). METHODS: Forty-two postmenopausal women with uncontrolled T2D were randomly allocated into vildagliptin or gliclazide MR (control) groups. The primary endpoint was the change in the BTMs in months 6 and 12 compared with the baseline. The secondary endpoint was the variation in the BMD, which was assessed via dual-energy X-ray absorptiometry at the lumbar spine, femoral neck and total hip at baseline and month 12. RESULTS: After a 12-month treatment, the BTM serum carboxy-terminal telopeptide of type 1 collagen increased 0.001 ± 0.153 ng/mL in the vildagliptin group versus 0.008 ± 0.060 ng/mL in the gliclazide MR group (p = 0.858). The serum osteocalcin, serum amino-terminal propeptide of procollagen type I and urinary amino-terminal telopeptide of type 1 collagen remained stable in both groups, and there was no statistically significant difference between the effect of vildagliptin and gliclazide MR on these variables. The lumbar spine BMD did not change in the vildagliptin or gliclazide MR groups after a 12-month treatment (0.000 ± 0.025 g/cm2 versus -0.008 ± 0.036, respectively, p = 0.434). Furthermore, there was a similar lack of change in the femoral neck and total hip BMD values in both treatments. CONCLUSIONS: Bone turnover markers and BMD remained unchanged after a 12-month treatment in both groups, which suggests that vildagliptin has the same safety profile as gliclazide MR on bone metabolism. Trial Registration ClinicalTrials.gov number NCT01679899.

Secondary hyperparathyroidism status in Brazil: Brazilian census of parathyroidectomy.

INTRODUCTION: Secondary hyperparathyroidism (SHP) is a common and serious complication of chronic kidney disease (CKD), with a negative impact on morbidity and mortality. Despite advances in the clinical management of SHP, treatment failure still occurs in a significant number of patients. In such cases, parathyroidectomy (PTx) is indicated. OBJECTIVE: To have an overview of the prevalence of severe SHP and of its surgical treatment in hemodialysis (HD) patients in Brazil. METHODS: This was an observational and descriptive study. Data were obtained from questionnaires posted to 660 dialysis units (DU). RESULTS: Results are expressed in absolute values and percentages, or means and standard deviation, as appropriate. 226 (34%) DU answered the questionnaire, providing data about 32,264 HD patients. The prevalence rate of severe SHP (PTH > 1,000 pg/mL) was 10.7 % (n = 3,463). 68 hospitals countrywide perform PTX. Around 40% of them are university centers. 49 (21.7%) DU reported not to have a specialized medical center to refer their patients with severe SHP. 74 (33%) DU reported that the time interval between surgery indication and its performance was over 6 months. The main recognized obstacles to surgery performance were: difficulty to perform the preoperative exams, lack of head and neck surgeons and the long waiting time. CONCLUSIONS: Although severe SHP is highly prevalent in Brazil, a significant number of patients do not have access to PTx. Better public health policies and liaison between nephrologists and head and neck surgeons are urgently required to change this reality.

Situação do hiperparatireoidismo secundário autônomo no Brasil: dados do censo brasileiro de paratireoidectomia / Secondary hyperparathyroidism status in Brazil: Brazilian census of parathyroidectomy

INTRODUÇÃO: O hiperparatireoidismo secundário (HPS) é uma complicação comum e grave no curso da doença renal crônica (DRC), com impacto direto sobre a morbidade e mortalidade desses pacientes. Apesar dos avanços no tratamento clínico do HPS a falência terapêutica ocorre em parcela significativa dos pacientes. Nesses casos, a paratireoidectomia (PTx) é indicada. OBJETIVO: Este trabalho visa abordar a situação atual no Brasil de pacientes com HPS em hemodiálise com indicação de PTx. MÉTODOS: Estudo observacional, descritivo, com dados obtidos de questionário enviado a 660 centros de diálise (CD). RESULTADOS: Os resultados estão expressos em valores absolutos, médias e desvio padrão; 226 (34 por cento) CD responderam ao questionário, representando 32.264 pacientes em hemodiálise (HD). A prevalência de pacientes com paratormônio (PTH) > 1.000pg/mL foi de 3.463 (10,7 por cento). Em 49 (21,7 por cento) CD não é possível encaminhar os pacientes para PTx. Cerca de 40 por cento dos serviços que realizam PTx são ligados a centros universitários. Em 74 (33 por cento) CD o tempo de espera para que um paciente seja operado é superior a 6 meses. Foram contabilizados 68 serviços que realizam PTx. Os principais problemas relacionados para a realização de PTx foram: dificuldades com a realização dos exames pré-operatórios, escassez de cirurgiões de cabeça e pescoço, e longa fila de espera. CONCLUSÕES: a prevalência de HPS grave é elevada em nosso meio. Uma parcela significativa de pacientes não tem acesso ao tratamento cirúrgico. Uma melhor organização das políticas de saúde pública, além de um maior entrosamento entre nefrologistas e cirurgiões de cabeça e pescoço, em torno dessa questão, são necessários para a mudança dessa realidade.

INTRODUCTION: Secondary hyperparathyroidism (SHP) is a common and serious complication of chronic kidney disease (CKD), with a negative impact on morbidity and mortality. Despite advances in the clinical management of SHP, treatment failure still occurs in a significant number of patients. In such cases, parathyroidectomy (PTx) is indicated. OBJECTIVE: To have an overview of the prevalence of severe SHP and of its surgical treatment in hemodialysis (HD) patients in Brazil. METHODS: This was an observational and descriptive study. Data were obtained from questionnaires posted to 660 dialysis units (DU). RESULTS: Results are expressed in absolute values and percentages, or means and standard deviation, as appropriate. 226 (34 percent) DU answered the questionnaire, providing data about 32,264 HD patients. The prevalence rate of severe SHP (PTH > 1,000 pg/mL) was 10.7 percent (n = 3,463). 68 hospitals countrywide perform PTX. Around 40 percent of them are university centers. 49 (21.7 percent) DU reported not to have a specialized medical center to refer their patients with severe SHP. 74 (33 percent) DU reported that the time interval between surgery indication and its performance was over 6 months. The main recognized obstacles to surgery performance were: difficulty to perform the preoperative exams, lack of head and neck surgeons and the long waiting time. CONCLUSIONS: Although severe SHP is highly prevalent in Brazil, a significant number of patients do not have access to PTx. Better public health policies and liaison between nephrologists and head and neck surgeons are urgently required to change this reality.

Phosphate binder impact on bone remodeling and coronary calcification--results from the BRiC study.

BACKGROUND AND AIMS: Calcium-containing phosphate binders have been shown to increase the progression of vascular calcification in hemodialysis patients. This is a prospective study that compares the effects of calcium acetate and sevelamer on coronary calcification (CAC) and bone histology. METHODS: 101 hemodialysis patients were randomized for each phosphate binder and submitted to multislice coronary tomographies and bone biopsies at entry and 12 months. RESULTS: The 71 patients who concluded the study had similar baseline characteristics. On follow-up, the sevelamer group had higher levels of intact parathyroid hormone (498 +/- 352 vs. 326 +/- 236 pg/ml, p = 0.017), bone alkaline phosphatase (38 +/- 24 vs. 28 +/- 15 U/l, p = 0.03) and deoxypyridinoline (135 +/- 107 vs. 89 +/- 71 nmol/l, p = 0.03) and lower LDL cholesterol (74 +/- 21 vs. 91 +/- 28 mg/dl, p = 0.015). Phosphorus (5.8 +/- 1.0 vs. 6 +/- 1.0 mg/dl, p = 0.47) and calcium (1.27 +/- 0.07 vs. 1.23 +/- 0.08 mmol/l, p = 0.68) levels did not differ between groups. CAC progression (35 vs. 24%, p = 0.94) and bone histological diagnosis at baseline and 12 months were similar in both groups. Patients of the sevelamer group with a high turnover at baseline had an increase in bone resorption (eroded surface, ES/BS = 9.0 +/- 5.9 vs. 13.1 +/- 9.5%, p = 0.05), whereas patients of both groups with low turnover at baseline had an improvement in bone formation rate (BFR/BS = 0.015 +/- 0.016 vs. 0.062 +/- 0.078, p = 0.003 for calcium and 0.017 +/- 0.016 vs. 0.071 +/- 0.084 microm(3)/microm(2)/day, p = 0.010 for sevelamer). CONCLUSIONS: There was no difference in CAC progression or changes in bone remodeling between the calcium and the sevelamer groups.

Association of changes in bone remodeling and coronary calcification in hemodialysis patients: a prospective study.

BACKGROUND: Vascular calcification is common and constitutes a prognostic marker of mortality in the hemodialysis population. Derangements of mineral metabolism may influence its development. The aim of this study is to prospectively evaluate the association between bone remodeling disorders and progression of coronary artery calcification (CAC) in hemodialysis patients. STUDY DESIGN: Cohort study nested within a randomized controlled trial. SETTING & PARTICIPANTS: 64 stable hemodialysis patients. PREDICTOR: Bone-related laboratory parameters and bone histomorphometric characteristics at baseline and after 1 year of follow-up. OUTCOMES: Progression of CAC assessed by means of coronary multislice tomography at baseline and after 1 year of follow-up. Baseline calcification score of 30 Agatston units or greater was defined as calcification. Change in calcification score of 15% or greater was defined as progression. RESULTS: Of 64 patients, 38 (60%) of the patients had CAC and 26 (40%) did not [corrected]. Participants without CAC at baseline were younger (P < 0.001), mainly men (P = 0.03) and nonwhite (P = 0.003), and had lower serum osteoprotegerin levels (P = 0.003) and higher trabecular bone volume (P = 0.001). Age (P = 0.003; beta coefficient = 1.107; 95% confidence interval [CI], 1.036 to 1.183) and trabecular bone volume (P = 0.006; beta coefficient = 0.828; 95% CI, 0.723 to 0.948) were predictors for CAC development. Of 38 participants who had calcification at baseline, 26 (68%) had CAC progression in 1 year. Progressors had lower bone-specific alkaline phosphatase (P = 0.03) and deoxypyridinoline levels (P = 0.02) on follow-up, and low turnover was mainly diagnosed at the 12-month bone biopsy (P = 0.04). Low-turnover bone status at the 12-month bone biopsy was the only independent predictor for CAC progression (P = 0.04; beta coefficient = 4.5; 95% CI, 1.04 to 19.39). According to bone histological examination, nonprogressors with initially high turnover (n = 5) subsequently had decreased bone formation rate (P = 0.03), and those initially with low turnover (n = 7) subsequently had increased bone formation rate (P = 0.003) and osteoid volume (P = 0.001). LIMITATIONS: Relatively small population, absence of patients with severe hyperparathyroidism, short observational period. CONCLUSIONS: Lower trabecular bone volume was associated with CAC development, whereas improvement in bone turnover was associated with lower CAC progression in patients with high- and low-turnover bone disorders. Because CAC is implicated in cardiovascular mortality, bone derangements may constitute a modifiable mortality risk factor in hemodialysis patients.

Fisiopatologia do hiperparatireoidismo secundário / Pathophysiology of secondary hyperparathyroidism

O hiperparatireoidismo secundário desenvolve-se cedo no curso da doença renal crônica como um mecanismo compensatório para controlar os níveisséricos de cálcio, fósforo e vitamina D. Seu controle inadequado está associado a conseqüências clínicas importantes, como calcificação vascular, e a umimpacto negativo na sobrevida do paciente renal crônico. O conhecimento de sua patogênese é importante para uma escolha terapêutica adequada.Recentemente, a descoberta do receptor de cálcio e das fosfatoninas acrescentou significativos avanços acerca do assunto. Nessa revisão, os mecanismosfisiopatológicos do hiperparatireoidismo secundário são examinados em tópicos: papel do cálcio e do seu receptor, do fósforo, da vitamina D e daresistência óssea ao PTH. Além disso, o papel do fator de crescimento de fibroblastos–23 também é discutido. Embora abordados separadamente, estesfatores estão inter-relacionados podendo um ou mais deles predominar de acordo com o tipo e a fase da doença renal crônica.

Secondary hyperparathyroidism (SHPT) occurs early in the course of chronic kidney disease (CKD) as an adaptive mechanism to control the serum levelsof calcium, phosphorus and vitamin D. If not treated adequately, it is associated with serious complications, like vascular calcification, with a negative impacton survival of CKD patients. A better understanding of its pathogenesis can help clinicians as to an appropriate therapeutic choice for SHPT. In this regard, the recent identification of both the calcium sensing receptor and the phosphatonins have shed some light to the field. In the present review, thepathophysiologic pathway of the SHPT is discussed in topics: role of calcium and calcium sensing receptor, role of phosphorus, and role of vitamin D andbone resistance to PTH. Furthermore, the role of fibroblast growth factor-23 is also discussed. Although analyzed separately, these factors are inter-related and according to the etiology and phase of CKD one or more of them may prevail.