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Guidelines call for decreasing phosphate, maintaining calcium levels in patients with CKD–MBD

The Kidney Disease: Improving Global Outcomes, or KDIGO, 2017 Clinical Practice Guideline Update for chronic kidney disease–mineral and bone disorder was recently published in Annals of Internal Medicine, emphasizing that serum phosphate levels be reduced, serum calcium levels be maintained and parathyroid hormone abnormalities be addressed in patients with the condition.

“Chronic kidney disease (CKD) is defined as abnormalities in kidney structure or function that are present for more than 3 months and have health implications... As kidney function decreases, marked changes in bone mineral metabolism occur, resulting in increased risk for fractures, cardiovascular disease, and overall mortality,” Markus Ketteler, MD, from Klinikum Coburg, Germany, and colleagues wrote.

Ketteler and colleagues developed the updated clinical practice guideline based on relevant systematic reviews to assist physicians in diagnosing, evaluating, preventing and treating chronic kidney disease–mineral and bone disorder (CKD–MBD).

The update includes revisions to multiple recommendations for patients with CKD stage G3a to G5D. Bone mineral density testing should be performed in patients who have suspected CKD–MBD and/or osteoporosis risk factors to determine their fracture risk, according to the guideline.

If treatment decisions would be impacted by the type of renal osteodystrophy, physicians should perform a bone biopsy.

Consecutive assessments of phosphate, calcium and parathyroid hormone levels should be conducted to inform which CKD–MBD treatment should be used. The guideline also recommends that elevated phosphate levels be lowered to and maintained in the normal range. Hypercalcemia should be avoided in these patients, according to the researchers.

A dialysate calcium concentration between 1.25 and 1.5 mmol/L should be used in patients with CKD G5D.

The researchers also suggest that physicians base their decisions about phosphate-lowering treatment for patients with CKD G3a to G5D on progressively or persistently elevated serum phosphate. The dose of calcium-based phosphate binders should be restricted in adult patients with CKD stage G3a to G5D receiving phosphate-lowering treatment. Physicians should limit the intake of dietary phosphate when treating patients for hyperphosphatemia alone or hyperphosphatemia and other conditions, according to the guideline.

The optimal parathyroid hormone level for patients not on dialysis is unknown, but the researchers recommend that those with gradually increasing levels or levels consistently above the upper normal limit for the assay be assessed for hyperphosphatemia, hypocalcemia, high phosphate intake and vitamin D deficiency.

Additionally, physicians should not routinely use calcitriol and vitamin D analogues for patients not on dialysis, though they can use these analogues for those with CKD stage G4 to G5 with severe and progressive hyperparathyroidism. The researchers recommend that calcimimetics, calcitriol or vitamin D analogues or a combination of calcimimetics with calcitriol or vitamin D analogues be used in patients with CKD stage G5D who require parathyroid hormone lowering therapy.

Treatment decisions should consider bone biopsy and the magnitude and reversibility of the biochemical abnormalities and the progression of CKD in patients with CKD G3a to G5D with biochemical abnormalities of CKD–MBD and low bone mineral density and/or fragility fractures, according to the guideline.

“Despite the recent clinical trials discussed in the updated guideline, significant gaps remain in the knowledge base for treatment of CKD–MBD, as demonstrated by the relatively small number of recommendations updated in the 2017 guideline,” Ketteler and colleagues concluded. “Future research should address many of these gaps.” – by Alaina Tedesco

Disclosure: Ketteler reports receiving grants from Amgen and personal fees from Amgen, Fresenius Medical Care, Medice, Sanofi and Vifor Fresenius Medical Care Renal Pharma. Please see study for all other authors’ relevant financial disclosures.