From the Guidelines
Evaluation of a patient for Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) should include regular monitoring of serum calcium, phosphorus, parathyroid hormone (PTH), and vitamin D levels, along with assessment of bone health and vascular calcifications. For patients with CKD stages 3-5D, measure serum calcium and phosphorus every 1-3 months, PTH every 3-6 months, and 25-hydroxyvitamin D levels annually, as recommended by the Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline update 1. Target phosphorus levels within the normal range (2.5-4.5 mg/dL), calcium within normal limits (8.5-10.2 mg/dL), and PTH levels based on CKD stage (generally 2-9 times the upper limit of normal for dialysis patients) 1. Some key points to consider in the evaluation of CKD-MBD include:
- Bone mineral density testing should be performed to assess fracture risk, particularly in patients with CKD stages 3-5D with evidence of CKD-MBD 1.
- Lateral abdominal X-rays can help detect vascular calcifications, while bone biopsies may be necessary in certain cases to diagnose specific bone disorders 1.
- The 2017 KDIGO clinical practice guideline update provides recommendations for the diagnosis, evaluation, prevention, and treatment of CKD-MBD, including the use of DXA BMD testing and bone biopsy 1.
- More recent studies, such as the 2023 expert consensus statement from ERKNet and OxalEurope, also provide guidance on the evaluation and management of CKD-MBD, including the measurement of serum intact parathyroid hormone (iPTH), calcium, phosphorus, alkaline phosphatase (ALP), and bicarbonate levels 1. This comprehensive evaluation is crucial because CKD-MBD involves complex interactions between declining kidney function and mineral metabolism, leading to bone abnormalities, vascular calcifications, and increased cardiovascular risk, as noted in the Annals of Internal Medicine 1 and the Journal of the American College of Radiology 1. Early detection and management can help prevent complications like fractures, cardiovascular events, and mortality associated with mineral and bone disorders in CKD patients.
From the FDA Drug Label
Ninety-six percent of patients were on hemodialysis and 4% on peritoneal dialysis. At study entry, 66% of the patients were receiving vitamin D sterols and 93% were receiving phosphate binders. Cinacalcet (or placebo) was initiated at a dose of 30 mg once daily and titrated every 3 or 4 weeks to a maximum dose of 180 mg once daily to achieve an iPTH of ≤ 250 pg/mL The dose was not increased if a patient had any of the following: iPTH ≤ 200 pg/mL, serum calcium < 7.8 mg/dL, or any symptoms of hypocalcemia.
To evaluate a patient for Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), the following steps can be taken:
- Measure iPTH levels: Evaluate the patient's intact parathyroid hormone (iPTH) levels, with a goal of achieving an iPTH of ≤ 250 pg/mL.
- Assess serum calcium levels: Monitor serum calcium levels, with a target range of ≥ 7.8 mg/dL to avoid hypocalcemia.
- Evaluate phosphate levels: Assess serum phosphorus levels, as phosphate binders may be necessary to control hyperphosphatemia.
- Consider vitamin D sterols: Evaluate the need for vitamin D sterols in patients with CKD-MBD, as 66% of patients in the study were receiving these supplements.
- Monitor Ca x P product: Calculate the Ca x P product to assess the risk of cardiovascular calcification and bone disease. These steps can help guide the evaluation and management of patients with CKD-MBD, although the specific approach may vary depending on individual patient needs and circumstances 2.
From the Research
Evaluation of CKD-MBD
To evaluate a patient for Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), the following steps can be taken:
- Assess serum calcium, phosphorus, and parathyroid hormone (PTH) levels, as abnormalities in these parameters are common in CKD-MBD 3
- Evaluate vitamin D status, as vitamin D deficiency is associated with secondary hyperparathyroidism and mineral and bone disorder in CKD 4, 5
- Consider the patient's kidney function, as CKD-MBD is a complex and multifactorial process that involves alterations in mineral metabolism, bone turnover, and vascular calcification 6
- Monitor for bone fragility, as CKD-MBD is associated with an increased risk of fractures and osteoporosis 6, 5
Laboratory Parameters
The following laboratory parameters can be used to evaluate CKD-MBD:
- Serum calcium and phosphorus levels, which can be abnormal in CKD-MBD 3, 7
- Intact parathyroid hormone (iPTH) levels, which can be elevated in CKD-MBD 3, 7
- Vitamin D levels, which can be deficient in CKD-MBD 4, 5
- Fibroblast growth factor-23 (FGF-23) levels, which can be elevated in CKD-MBD 6, 5
Treatment Targets
The following treatment targets can be used to manage CKD-MBD: