Chronic kidney disease-mineral and bone disorder

Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD)

Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) is a systemic disorder of mineral and bone metabolism due to chronic kidney disease (CKD). It is characterized by abnormalities in calcium, phosphorus, parathyroid hormone (PTH), or vitamin D metabolism, abnormalities in bone turnover, mineralization, volume, linear growth, or strength, and vascular or other soft-tissue calcification.

Pathophysiology

CKD-MBD arises due to the kidneys' reduced ability to excrete phosphate, leading to hyperphosphatemia. This condition stimulates the secretion of fibroblast growth factor 23 (FGF23) and suppresses the production of calcitriol (active vitamin D). The decreased levels of calcitriol lead to hypocalcemia, which in turn stimulates the parathyroid glands to secrete more PTH, resulting in secondary hyperparathyroidism. Over time, these changes can lead to bone disease and vascular calcification.

Clinical Manifestations

Patients with CKD-MBD may present with bone pain, fractures, and skeletal deformities. Vascular calcification can lead to cardiovascular complications, which are a major cause of morbidity and mortality in CKD patients. Laboratory findings often include elevated serum phosphate, low or normal serum calcium, elevated PTH, and low levels of calcitriol.

Diagnosis

The diagnosis of CKD-MBD is based on clinical evaluation, laboratory tests, and imaging studies. Key laboratory tests include serum calcium, phosphate, PTH, and vitamin D levels. Bone density scans and X-rays may be used to assess bone health and detect vascular calcification.

Management

Management of CKD-MBD involves controlling serum phosphate levels through dietary phosphate restriction and the use of phosphate binders. Vitamin D analogs and calcimimetics may be used to manage secondary hyperparathyroidism. Regular monitoring of mineral levels and bone health is essential.

Prognosis

The prognosis of CKD-MBD depends on the stage of CKD and the effectiveness of treatment. Early intervention can help prevent complications, but advanced CKD-MBD is associated with increased risk of fractures and cardiovascular events.

Also see

• Chronic kidney disease
• Hyperparathyroidism
• Vascular calcification
• Bone mineral density