The role of vitamin D in mild to moderate chronic kidney disease

Secondary Hyperparathyroidism in Chronic Kidney Disease: Focus on Clinical Consequences and Vitamin D Therapies

Objective:

To assess vitamin D–based treatment approaches for secondary hyperparathyroidism and its complications.

Data Sources:

A literature search was performed using MEDLINE (1990–February 28, 2006). Key words used were chronic kidney disease and vitamin D to identify relevant papers published in English.

Study Selection and Data Extraction:

From the database of articles generated, 48 papers were identified. Titles and abstracts were examined to identify those directly related to the objective. Discussion was expanded through the bibliographies of cited articles.

Data Synthesis:

The increasing prevalence of chronic kidney disease (CKD) in the US indicates an urgent need for treatment strategies to delay or prevent disease progression. Abnormalities in phosphorus and calcium homeostasis, vitamin D levels, and the subsequent development of secondary hyperparathyroidism (SHPT) are secondary complications of CKD associated with increased morbidity and mortality. Management options include dietary phosphorus restriction, phosphate binders and/or calcium supplementation, vitamin D supplementation, and calcimimetics. Vitamin D supplementation has received increased attention given the prevalence of vitamin D deficiency in patients with CKD and the beneficial effect of correcting this deficiency.

Conclusions:

Early identification and intervention appropriate to the stage of CKD are likely to improve patient outcomes. Improved knowledge of interactions between vitamin D and vitamin D receptors has led to the development of vitamin D analogs and calcimimetics, which offer benefits in the management of SHPT. Integrating available treatment options into practice to achieve optimal therapeutic goals of SHPT based on the stage of CKD is a significant challenge for pharmacists managing patients with CKD.

Systemic disorders of calcium dynamics in rats with adenine-induced renal failure: implication for chronic kidney disease-related complications

AIM

Chronic kidney disease (CKD) causes the dysregulation of systemic mineral metabolism. A major issue in CKD patients is the emergence of ectopic calcification in soft tissues, presumably due to increased levels of calcium (Ca) or inorganic phosphorus (Pi); however, the precise mechanisms have not been fully elucidated. Therefore, this study aims to evaluate Ca dynamics in an animal model of CKD.

METHODS

Renal failure was produced in rats by feeding an adenine-containing diet for 4 weeks, and time-course changes in biochemical parameters, including Ca, Pi, creatinine (Cr), blood urea nitrogen (BUN), parathyroid hormone (PTH), 1,25-dihydroxyvitamin D(3), and N-telopeptide and cross-linked collagen type I (NTx), were monitored once a week during the feeding period. Intestinal absorption, tissue contents, and urinary excretion of Ca were monitored using radioisotope (RI) (45)Ca.

RESULTS

Adenine-fed rats exhibited renal failure, ectopic calcification and altered serum parameters, including elevated levels of serum Pi, Cr, PTH and BUN. Serum Ca levels were not increased in rats with renal failure. RI-based experiments revealed that abnormal Ca dynamics including attenuated intestinal absorption, increased incorporation into soft tissues, particularly aortic tissue, in which it was increased threefold, and enhanced urinary excretion occurred in renal failure rats.

CONCLUSION

Rats with renal failure induced by an adenine diet exhibited severe abnormality of Ca dynamics, including Ca shortage and ectopic accumulation of Ca. These findings would provide useful information to research CKD-related complications.

Impact of secondary hyperparathyroidism on disease progression, healthcare resource utilization and costs in pre-dialysis CKD patients

BACKGROUND AND OBJECTIVES

Secondary hyperparathyroidism (SHPT) can lead to significant morbidity, mortality, and additional healthcare resource utilization in chronic kidney disease (CKD) stage 5. The objective of this study was to examine healthcare costs and utilization, and the risks of dialysis or mortality, among pre-dialysis CKD patients with and without SHPT.

RESEARCH DESIGN AND METHODS

This retrospective cohort study examined insurance claims from 66 644 adult, pre-dialysis, CKD patients with and without SHPT during a 72-month period. Annualized estimates of healthcare costs and utilization, and disease progression to dialysis or death following index CKD diagnosis were compared.

RESULTS

Post-index annualized costs and inpatient healthcare resource utilization was higher in those with SHPT in both unadjusted and adjusted (controlling for gender, age, plan type, payer type, geographic region, physician specialty, pre-index co-morbidities, and pre-index total healthcare costs), and unmatched and matched analyses. Kaplan-Meier analysis demonstrated that the rate of progression to dialysis or death was higher for CKD with SHPT compared to CKD without SHPT, and Cox proportional hazard models suggested that CKD patients with SHPT were more than four to five times as likely to initiate dialysis or die as compared to CKD without SHPT.

CONCLUSION

SHPT in pre-dialysis CKD patients is associated with significantly greater healthcare costs, inpatient hospitalizations, and a faster rate of disease progression compared to pre-dialysis CKD without SHPT. Since observational studies are designed to demonstrate associations rather than causality, further investigation is required to confirm these findings.