At what Glomerular Filtration Rate (GFR) cutoff do patients start to develop bone mineral disease, also known as Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD)?

From the Guidelines

Patients typically start to develop bone mineral disease when their glomerular filtration rate (GFR) falls below 60 mL/min/1.73m², corresponding to stage 3 chronic kidney disease (CKD) [ 1 ].

Key Points

• Bone mineral disease, also known as Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), is a common complication of chronic kidney disease (CKD) [ 1 ].
• The development of CKD-MBD is closely related to the decline in kidney function, particularly when GFR falls below 60 mL/min/1.73m² [ 1 ].
• As kidney function continues to decline, especially below 30 mL/min/1.73m² (stage 4 CKD), secondary hyperparathyroidism develops, further exacerbating bone mineral disease [ 1 ].
• Management of CKD-MBD should begin early with monitoring of calcium, phosphate, parathyroid hormone (PTH), and vitamin D levels [ 1 ].
• Interventions may include dietary phosphate restriction, phosphate binders, vitamin D supplementation, and calcimimetics like cinacalcet for severe secondary hyperparathyroidism [ 1 ].

Recommendations

• Monitor serum levels of phosphorus, calcium, and PTH when GFR falls below 60 mL/min/1.73m² and monitor these parameters thereafter in patients with CKD [ 1 ].
• Base treatment on trends in laboratory values rather than a single abnormal result and be cautious to avoid hypercalcemia when treating secondary hyperparathyroidism [ 1 ].
• Early recognition and management of CKD-mineral bone disorder is crucial to prevent complications such as vascular calcification, bone fractures, and increased cardiovascular morbidity and mortality [ 1 ].

From the Research

Glomerular Filtration Rate (GFR) Cutoff for Bone Mineral Disease

• The GFR cutoff at which patients start to develop bone mineral disease, also known as Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), is a topic of interest in several studies 2, 3, 4, 5.
• According to a study published in 2002, bone disease is observed in 75-100% of patients with chronic renal failure as the GFR falls below 60 ml/minute 2.
• Another study from 1975 notes that mild abnormalities in parathyroid hormone (PTH) secretion occur even when the GFR is greater than 30 cc/min, indicating that bone mineral disease may commence early in the course of renal failure 3.
• A 2016 guideline for the diagnosis, treatment, and management of CKD-MBD suggests that pathophysiologic mechanisms begin to occur early in CKD, but biochemical and bone matrix abnormalities become clinically apparent when the GFR declines to <50% of normal 4.
• A study from 1999 found that skeletal changes are initiated at an early stage of chronic renal failure, with reduced bone mineral density (BMD) and elevated levels of PTH and biochemical markers of bone turnover observed in patients with a mean GFR of 37 ml/min 5.
• While there is no single GFR cutoff value universally agreed upon, these studies suggest that bone mineral disease may develop at a GFR below 60 ml/minute 2 or when the GFR declines to <50% of normal 4.

Key Findings

• Bone mineral disease is a common complication of chronic kidney disease (CKD) 2, 3, 4.
• The GFR cutoff for bone mineral disease may vary depending on the population and the specific criteria used to define the disease 2, 4, 5.
• Early intervention and careful use of effective therapies can reduce the morbidity associated with bone mineral disease in CKD patients 2, 3, 4.