What is renal osteodystrophy?
Renal osteodystrophy, also known as renal osteodystrophy , is one of the main complications of chronic kidney disease (CKD) patients. It is a serious bone damage secondary to CKD, which can cause abnormalities in bone transformation, mineralization, volume, linear growth and strength. As well as calcification of blood vessels or other soft tissues, increasing the risk of fractures and even death in CKD patients, manifested as bone pain, fractures, bone deformation, joint pain, muscle weakness, etc. Bone pain often occurs in the waist, back, and pelvis. It can occur also in the lower limbs, especially the thighs, ankles and heels, and often worsens when changing positions.
Renal osteodystrophy is caused and mediated by a variety of different factors, the main cause of which is renal failure, which is unable to remove metabolic waste from the body in time, resulting in increased serum phosphate concentration, which in turn leads to a decrease in serum calcium, the formation of calcium-phosphorus products, and bone tissue lesions. Changes in calcium concentration are regulated by the activity of calcium-sensitive receptors in parathyroid cells and stimulate or inhibit the secretion of parathyroid hormone (PTH). Long-term hypocalcemia promotes the development of parathyroid hyperplasia and significantly increases the content of parathyroid tissue available for PTH synthesis.
When PTH levels rise, it enhances calcium mobilization in bones, increases calcium and phosphorus reabsorption in the proximal renal tubules and intestines, and restores blood calcium levels through serum 25-hydroxyvitamin D. However, CKD patients experience severe dysfunction in the concentration and function of cytokines and hormones that regulate bone turnover, making it impossible to maintain normal blood calcium levels, ultimately leading to renal osteodystrophy[1].
Diagnosis of renal osteodystrophy
Bone biopsy is the gold standard for diagnosing renal osteodystrophy. Bone biopsy is generally safe, with a complication rate of about 0.5%. Before biopsy, dual labeling with tetracycline is crucial for diagnosis. Tetracycline can promote bone union and help with histological diagnosis. Serological markers can also be used for diagnosis. The most important marker is intact PTH. Generally speaking, serum PTH >450 pg/ml can be used as a diagnostic standard. In addition, bone-specific alkaline phosphatase and osteocalcin are both synthesized in osteoblasts. It can also be used as markers for detecting osteoblast activity.
Treatment of renal osteodystrophy
General early treatment
Pay attention to diet, it is recommended to avoid excessive protein intake, limit phosphate to 800 mg/d, and give active vitamin D metabolites after serum phosphate levels normalize.
Drug treatment
Generally, targeted treatment is carried out for important targets of the disease. (1) Targeted PTH treatment: The phosphate transporter EOS789 is use to inhibit the absorption of phosphorus. Reduce the levels of fibroblast growth factor 23 and PTH, and delay the deterioration of kidney disease; calcimimetic agents such as cinacalcet and etidakatide are used to increase the receptor’s response to serum calcium through allosteric binding mechanism and activation of calcium-sensitive receptors , reduce PTH content and fracture risk, and do not increase intestinal absorption of calcium and phosphorus.
(2) Targeted bone treatment: There are 6 bisphosphonates approved by the US Food and Drug Administration for the treatment of renal osteodystrophy. Including zoledronate, pyridyl bisphosphonate, alendronate , etc. Which can increase bone mass. Increase bone strength, prevent bone loss, and reduce the risk of fracture.
(3) Traditional Chinese medicine treatment: Traditional Chinese medicine theory believes that “the kidney produces marrow to fill the bones”. The main pathogenesis of renal osteodystrophy is in the kidney. Which is closely related to the deficiency of the liver and spleen. According to TCM, acupuncture and Chinese medicine can be used for combined treatment of different syndromes.,
In short, once CKD patients experience problems such as back pain and leg pain. They must not ignore them, as they may be signs of chronic bone malnutrition
