Race and Ethnicity Predict Bone Markers and Fracture in Pediatric Patients With Chronic Kidney Disease

Phenotypes of Mineral Bone Disorder in Chronic Kidney Disease in a Dialysis Population

BACKGROUND

Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) is associated with clinical outcomes. It is necessary to identify the phenotype to make clinical decisions that optimize resources and follow-up.

OBJECTIVE

To determine the frequency of the CKD-MBD phenotype in dialysis patients and the associated factors.

METHODS

Cross-sectional study in 440 patients, evaluated for CKD-MBD. Phenotypes show frequency of high, low or on target levels of PTH, vitamin D and phosphorus. The most common phenotype was used for comparisons.

RESULTS

Age was 37.5 ± 15.8 years, 53% male, 28% were diabetic, 60% on peritoneal dialysis (PD), dialysis vintage was 12.0 months (IQR 3.0-34.3). High PTH was 58%, low vitamin D 82%, high phosphorus 39%, low calcium 50%, and vascular calcification 55%. The combination of high PTH and low vitamin D and high on-target phosphorus was 39%. Those with high PTH and low vitamin D were more likely to use PD (71 vs 51%; p <0.0001), had higher lipids: total cholesterol (159 vs. 152; p = 0.002) and triglycerides (137 vs. 123; p = 0.02), higher potassium (4.7 ± 0.7 vs. 4.9 ± 0.9 mg/dL; p = 0.04), and higher serum creatinine (11.9 ± 4.4 vs. 10.6 ± 3.7 mg/dL; p = 0.01). Predictors of the most common phenotypes were PD use, total cholesterol, and serum creatinine.

CONCLUSIONS

More than one third (38%) of our sample of patients had high PTH and low vitamin D with either high or normal phosphorus. Patients with these phenotypes more frequently used PD, had higher lipids and low potassium. PD use, total cholesterol and serum creatinine were significantly associated with these phenotypes.

Transcription factor HNF4α2 promotes osteogenesis and prevents bone abnormalities in mice with renal osteodystrophy

Renal osteodystrophy (ROD) is a disorder of bone metabolism that affects virtually all patients with chronic kidney disease (CKD) and is associated with adverse clinical outcomes including fractures, cardiovascular events, and death. In this study, we showed that hepatocyte nuclear factor 4α (HNF4α), a transcription factor mostly expressed in the liver, is also expressed in bone, and that osseous HNF4α expression was dramatically reduced in patients and mice with ROD. Osteoblast-specific deletion of Hnf4α resulted in impaired osteogenesis in cells and mice. Using multi-omics analyses of bones and cells lacking or overexpressing Hnf4α1 and Hnf4α2, we showed that HNF4α2 is the main osseous Hnf4α isoform that regulates osteogenesis, cell metabolism, and cell death. As a result, osteoblast-specific overexpression of Hnf4α2 prevented bone loss in mice with CKD. Our results showed that HNF4α2 is a transcriptional regulator of osteogenesis, implicated in the development of ROD.

Mineral bone disorder in children with chronic kidney disease: Data from the KNOW-Ped CKD (Korean cohort study for outcome in patients with pediatric chronic kidney disease) study

BACKGROUND

Children with chronic kidney disease (CKD) are at high risk of mineral bone disorder (MBD), which leads to fractures, growth retardation, and cardiovascular disease. We aimed to comprehensively understand the relationship between renal function and factors related to MBD and evaluate the prevalence and distribution characteristics of MBD, specifically among Korean patients from the KNOW-PedCKD cohort.

METHODS

From the baseline data of the KNOW-PedCKD cohort, we examined the prevalence and distribution of MBD in 431 Korean pediatric CKD patients, including the level of corrected total calcium, serum phosphate, serum alkaline phosphatase, serum intact parathyroid hormone (iPTH), fibroblast growth factor 23 (FGF-23), serum vitamin D, fractional excretion of phosphate (FEP), and bone densitometry Z-scores.

RESULTS

The median serum calcium level remained relatively normal regardless of the CKD stage. The levels of 1,25-dihydroxy vitamin D, urine calcium-to-creatinine ratio, and bone densitometry Z-score significantly decreased with advancing CKD stage, while those of serum phosphate, FGF-23, and FEP significantly increased with CKD stage. The prevalence of hyperphosphatemia (17.4%, 23.7%, and 41.2% from CKD stages 3b, 4, and 5, respectively) and hyperparathyroidism (37.3%, 57.4%, 55.3%, and 52.9% from CKD stages 3a, 3b, 4, and 5, respectively) significantly increased with the CKD stage. Prescriptions of medications, such as calcium supplements (39.1%, 42.1%, 82.4%), phosphate binders (39.1%, 43.4%, 82.4%), and active vitamin D (21.7%, 44.7%, and 64.7%) significantly increased with CKD stage 3b, 4, and 5, respectively.

CONCLUSIONS

The results demonstrated the prevalence and relationship of abnormal mineral metabolism and bone growth according to CKD stage in Korean pediatric CKD patients for the first time.

Skeletal Outcomes in Children and Young Adults with Glomerular Disease

BACKGROUND

Children with glomerular disease have unique risk factors for compromised bone health. Studies addressing skeletal complications in this population are lacking.

METHODS

This retrospective cohort study utilized data from PEDSnet, a national network of pediatric health systems with standardized electronic health record data for more than 6.5 million patients from 2009 to 2021. Incidence rates (per 10,000 person-years) of fracture, slipped capital femoral epiphysis (SCFE), and avascular necrosis/osteonecrosis (AVN) in 4598 children and young adults with glomerular disease were compared with those among 553,624 general pediatric patients using Poisson regression analysis. The glomerular disease cohort was identified using a published computable phenotype. Inclusion criteria for the general pediatric cohort were two or more primary care visits 1 year or more apart between 1 and 21 years of age, one visit or more every 18 months if followed >3 years, and no chronic progressive conditions defined by the Pediatric Medical Complexity Algorithm. Fracture, SCFE, and AVN were identified using SNOMED-CT diagnosis codes; fracture required an associated x-ray or splinting/casting procedure within 48 hours.

RESULTS

We found a higher risk of fracture for the glomerular disease cohort compared with the general pediatric cohort in girls only (incidence rate ratio [IRR], 1.6; 95% CI, 1.3 to 1.9). Hip/femur and vertebral fracture risk were increased in the glomerular disease cohort: adjusted IRR was 2.2 (95% CI, 1.3 to 3.7) and 5 (95% CI, 3.2 to 7.6), respectively. For SCFE, the adjusted IRR was 3.4 (95% CI, 1.9 to 5.9). For AVN, the adjusted IRR was 56.2 (95% CI, 40.7 to 77.5).

CONCLUSIONS

Children and young adults with glomerular disease have significantly higher burden of skeletal complications than the general pediatric population.

Chronic kidney disease emerging trends in children and what to do about it

Chronic Kidney disease (CKD) is a major public health problem associated with increased health costs, morbidity, and mortality. There is a 30-fold higher mortality rate and severely impaired quality of life in children with chronic kidney disease (CKD), requiring dialysis or kidney transplant compared to the aged-match general population. The early diagnosis and treatment of pediatric CKD can reverse, delay or prevent progression to advanced kidney disease. It is worth noting that CKD with rapid progression, which carries a poor prognosis, is more common in African American children. Thus, the development of a universal pediatric CKD screening program for high-risk children can be vital for social equity. The disparity in prevalence and severity of CKD is likely due to a complex interaction between biological and nonbiological risk factors that influence the development and progression of CKD in children of African descent. For example, high-risk alleles in the gene encoding for apolipoprotein L1 (APOL1) have been recognized as the most important factor in the high incidence of some chronic kidney diseases in African Americans. In this review, we will focus on the trends in the incidence of pediatric CKD and management strategies aimed at enhancing health outcomes and reducing disease progression.

Adverse Consequences of Chronic Kidney Disease on Bone Health in Children

Chronic kidney disease (CKD) mineral bone disorder has long-term effects on skeletal integrity and growth. Abnormalities in serum markers of mineral metabolism are evident early in pediatric CKD. Bone deformities, poor linear growth, and high rates of fractures are common in children with CKD. Newer imaging modalities such as high-resolution peripheral quantitative computed tomography shows promise in assessing bone mineral density more comprehensively and predicting incident fractures. A lack of large-scale studies that provide a comprehensive assessment of bone histology and correlations with serum biomarkers has contributed to the absence of evidence-based guidelines and suboptimal management of CKD mineral bone disorder in children with CKD.