Bone biopsy in chronic kidney disease: still an option?

Focusing on Phosphorus Loads: From Healthy People to Chronic Kidney Disease

Phosphorus is an essential micromineral with a key role in cellular metabolism and tissue structure. Serum phosphorus is maintained in a homeostatic range by the intestines, bones, and kidneys. This process is coordinated by the endocrine system through the highly integrated actions of several hormones, including FGF23, PTH, Klotho, and 1,25D. The excretion kinetics of the kidney after diet phosphorus load or the serum phosphorus kinetics during hemodialysis support that there is a "pool" for temporary phosphorus storage, leading to the maintenance of stable serum phosphorus levels. Phosphorus overload refers to a state where the phosphorus load is higher than is physiologically necessary. It can be caused by a persistently high-phosphorus diet, renal function decline, bone disease, insufficient dialysis, and inappropriate medications, and includes but is not limited to hyperphosphatemia. Serum phosphorus is still the most commonly used indicator of phosphorus overload. Trending phosphorus levels to see if they are chronically elevated is recommended instead of a single test when judging phosphorus overload. Future studies are needed to validate the prognostic role of a new marker or markers of phosphorus overload.

A review and perspective on the assessment, management and prevention of fragility fractures in patients with osteoporosis and chronic kidney disease

This article aims to review the methods used for the assessment of fracture risk and the use of osteoporosis medications for fracture prevention in the population with CKD, and highlights the difficulties faced by clinicians in the management of these patients and the latest recommendations and guidelines. Chronic kidney disease (CKD) and osteoporosis often co-exist in older adults, and they present a major healthcare challenge. CKD mineral and bone disorder (CKD-MBD) occurs as renal function declines and this syndrome affects most patients in CKD stages 4 and 5. The biochemical abnormalities of CKD-MBD, renal bone disease and risk factors associated with age-related bone loss and osteoporosis lead to a cumulative effect on fracture risk and mortality. There is a need for routine evaluation of fracture risk and fracture prevention in this population. Measurement of bone mineral density (BMD) and the use of the FRAX tool have predictive value for incident fractures in the general population and in CKD. This enables physicians to identify CKD patients most at risk of sustaining a fragility fracture and allows a more targeted approach to fracture prevention. Data analysis from the pivotal trials of therapeutic agents used in osteoporosis show that these drugs can be considered in mild and moderate CKD (stages 1-3 CKD). Off-label drug use in patients with CKD-MBD and more severe renal impairment (CKD stages 4 and 5) could offer significant benefits to sub-groups of patients when carefully tailored to each individual's bone turnover and calcium and phosphate balance. However, this requires a selective approach and treatment decisions based on inference from pathophysiology while we await further trials. Guidelines advocate the correction and/or reduction of the biochemical abnormalities of CKD-MBD before initiation of treatment with osteoporosis drugs and close monitoring during treatment.