Longitudinal Changes of Cardiac Structure and Function in CKD (CASCADE Study)

Little is known regarding the natural longitudinal changes in cardiac structure and function in CKD. We hypothesized that baseline CKD stage is associated with progressive worsening in cardiac structure and function. We conducted a prospective longitudinal study, recruiting 300 patients with stages 3–5 CKD from a major regional tertiary center and university teaching hospital in Hong Kong. Baseline CKD stages were studied in relation to natural longitudinal changes in echocardiographic and tissue Doppler imaging–derived parameters. Over 1 year, the prevalence of left ventricular (LV) hypertrophy increased from 40.3% to 48.9%, median left atrial volume index increased 4.8 (interquartile range [IQR], 2.1, 7.7) ml/m² (P<0.001), peak systolic mitral annular velocity decreased 0.5 (IQR, −1.5, 0.5) cm/s (P<0.001), early diastolic mitral annular velocity decreased 0.5 (IQR, −1.5, 0.5) cm/s (P<0.001), and eGFR declined 2.0 (IQR, −5.0, 0.0) ml/min per 1.73 m². CKD stages 4 and 5 were associated with more baseline abnormalities in cardiac structure and function and predicted greater longitudinal progression in LV mass index (odds ratio [OR], 3.02; 95% confidence interval [95% CI], 1.39 to 6.58), volume index (OR, 2.58; 95% CI, 1.18 to 5.62), and left atrial volume index (OR, 2.61; 95% CI, 1.20 to 5.69) and worse diastolic dysfunction grade (OR, 3.17; 95% CI, 1.16 to 8.69) compared with stage 3a in the fully adjusted analysis. In conclusion, more advanced CKD at baseline may be associated with larger longitudinal increases in LV mass and volume and greater deterioration in diastolic function.     

Prevalence of chronic kidney disease (CKD) and significant contributors to CKD in HIV-infected patients

We investigated the prevalence of CKD and factors associated with CKD in HIV-infected patients who were under stable medical control. We retrospectively abstracted the medical records of 748 HIV-infected outpatients(659 males and 89 females). Their mean age was 44.9+/-11.7 (range; 21 to 79) years. The following parameters were reviewed: urinalysis including proteinuria and microscopic hematuria, urinary N-acetyl-beta-glucosaminidase (NAG) level as a marker of tubular damage, serum creatinine level, estimated glomerular filtration rate calculated based on the Modification of Diet in Renal Disease formula (eGFR), CD4 count in peripheral blood, HIV-RNA copies in serum, use and vintage of highly active antiretroviral therapy (HAART), and use of anti-hypertensive drugs (AHTD). Stages of CKD were determined based on the K/DOQI stages of kidney disease. Chronic renal failure (CRF) was defined as an eGFR value of less than 60 mL/min/1.73 m2. The chi-square test was used to evaluate differences in the prevalence of dichotomous variables. Multivariable logistic regression analysis was applied to assess independent contributors to existence of CRF, proteinuria, and tubular damage. Proteinuria was positive in 50.0 % and hematuria was positive in 11.3 %. Both were positive in 8.41%. Tubular damage (> 11 U/L of urinary NAG levels) was positive in 42 out of 112(37.5 %). Prevalence of CKD and CRF was 87.8 % and 16.2 %, respectively. Stages of CKD were: stage 5D, 4 patients (0.53 %); stage 5, 0 patients (0%); stage 4, 3 patients (0.40 %); stage 3, 114 patients (15.2 %); stage 2, 487 patients (65.1%); stage 1, 49 patients (6.6%); and non-CKD, 91 patients (12.2 %). Statistically, use of HAART, urinary NAG level, and age were significant contributors to proteinuria. Proteinuria, age, and use of AHTD were strong predictors for CRF. Tubular damage was related to HAART vintage, age, and TG levels. In addition, HAART vintage of more than 2.5 years was statistically associated with the existence of tubular damage in HIV-infected patients. Prevalence of CKD in stable HIV-infected patients was unexpectedly high in our hospital. Aged patients with a long HAART vintage who have proteinuria and hypertension are predisposed to the development of CRF through tubular damage.     

Regulation of parathyroid function in chronic kidney disease (CKD)

In chronic kidney disease (CKD), several abnormalities in bone and mineral metabolism develop in the majority of patients. The parathyroid plays a very important role in regulating bone and mineral metabolism; thus, control of parathyroid function is one of the main targets of the management of CKD-mineral and bone disorder (CKD-MBD). In the development of secondary hyperparathyroidism, it has recently been suggested that fibroblast growth factor 23 (FGF23) plays a crucial role, both as a phosphaturic factor and as a suppressor of active vitamin D (1,25D) production in the kidney. FGF23 is originally secreted to prevent hyperphosphatemia in CKD, but this occurs at the expense of low 1,25D and hyperparathyroidism (“trade-off” hypothesis revisited). Furthermore, recent data suggest that FGF23 could be another useful marker for the prognosis of hyperparathyroidism, because a high serum level may reflect the cumulative dose of vitamin D analogues previously administered. We have also demonstrated that severe hyperparathyroidism was associated with the production and secretion of a new form of parathyroid hormone (PTH) molecule, which can be detected by third-generation assays for PTH, but not by the second-generation assays. For the regression of already established nodular hyperplasia, the more advanced type of parathyroid hyperplasia, it is certainly necessary, in the near future, to develop new agents that specifically induce apoptosis in parathyroid cells. Until such agents are developed, prevention and early recognition of nodular hyperplasia is mandatory for the effective and safe management of hyperparathyroidism in CKD.     

Cardiovascular risk in chronic kidney disease (CKD): the CKD-mineral bone disorder (CKD-MBD)

Recent advances in our understanding of the excess mortality of chronic kidney disease (CKD) due to cardiovascular complications, obtained through observational studies, demonstrate that vascular calcification and hyperphosphatemia are major cardiovascular risk factors. Mechanistic studies demonstrate that these two risk factors are related and that hyperphosphatemia directly stimulates vascular calcification. The role of hyperphosphatemia in stimulating vascular calcification in CKD is associated with a block to the skeletal reservoir function in phosphate balance due to excess bone resorption. This has led to the realization that renal osteodystrophy is linked to vascular calcification by disordered mineral homeostasis (phosphate) and that a multiorgan system fails in CKD, leading to cardiovascular mortality. In children with renal disease, the multiorgan system fails, just as in adults, but the outcomes have been less well studied, and perceptions of differences from adults are possibly incorrect. Vascular calcification and cardiovascular mortality are less prevalent among pediatric patients, but they are present. However, CKD-induced vascular disease causes stiffness of the arterial tree causing, in turn, systolic hypertension and left ventricular hypertrophy as early manifestations of the same pathology in the adult. Because of the role of the skeleton in these outcomes, renal osteodystrophy has been renamed as the CKD mineral bone disorder (CKD-MBD). This review, which focuses on the pediatric patient population, describes our current state of knowledge with regards to the pathophysiology of the CKD-MBD, including the new discoveries related to early stages of CKD. As a new necessity, cardiovascular function issues are incorporated into the CKD-MBD, and new advances in our knowledge of this critical component of the disorder will lead to improved outcomes in CKD.     

Subtyping CKD Patients by Consensus Clustering: The Chronic Renal Insufficiency Cohort (CRIC) Study

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