Renal osteodystrophy, now known as Chronic Kidney Disease - Mineral Bone Disorder (CKD-MBD), is a condition that arises due to low calcium and high phosphorus levels. This situation arises due to inability of the kidneys to produce adequate calcitriol or active vitamin D, which is necessary for absorption of calcium from food. Hence, calcium is removed from the bone, leading to increase in levels of phosphorus.
Raised phosphorus levels are also due to inadequate removal of phosphorus from the body by the kidneys. Due to low calcium levels, parathyroid glands are stimulated and levels of parathyroid hormone are elevated. This hormone draws calcium from bones to maintain optimum blood calcium levels.
Over time with continuous removal of calcium from bones along with high phosphorus levels, bones become weak and brittle and carry high risk of developing fractures.
This condition is common in patients with existing kidney disease or in patients who are already on dialysis for long period of time. It can occur in both adults and children.
This condition is more severe in children, as many children do not manifest any symptoms of kidney disease, but damage to bones does occur. Chances of bone deformities, stunted growth and fractures is high. Children in growing age may develop deformity in the lower legs in the form of bending inside or outside. This condition is also referred to as renal rickets.
Signs and Symptoms of Renal Osteodystrophy / Mineral Bone Disorder (MB)
Renal Osteodystrophy primarily affects bone health. Patients might complain of bone/joint pain, increased tendency of fractures, bone deformities and stunted growth.
Most patients with renal osteodystrophy do not exhibit any symptoms. It affects kidney disease patients and most commonly those who are on dialysis for a few years.
The severity of symptoms is more in children, because when this condition affects children in the growing age, stunted growth, deformities and fractures risks increase.
Symptoms of Renal Osteodystrophy:
• Bone pain
• Joint pain
• Short stature
• Bone deformities
• Increased risk of bone fractures due to weak and brittle bones.
Diagnosis and Treatment of Renal Osteodystrophy / Mineral Bone Disorder (MB)
Renal Osteodystrophy or Chronic Kidney Disease- Mineral Bone Disorder is diagnosed by estimating the levels of calcium, phosphorus, parathyroid hormone and calcitriol in the blood. A bone biopsy is done to assess the bone density. Treatment is with diet modifications, dialysis and drug therapy.
The classical picture of lab reports in a patient with Renal Osteodystrophy shows:
• Low calcium levels
• High phosphorus levels
• Raised parathyroid hormone levels
• Low calcitriol levels
• A bone biopsy is also useful to check whether the cells are building normal bone or not
Treatment of Renal Osteodystrophy:
The main goal of treatment is to achieve balance between calcium, phosphorus levels. For this following steps need to be followed:
Maintaining phosphorus levels in the body:
• Foods that contain phosphorus like milk, cheese, beans, dark sodas and beer should be avoided.
• Drugs like phosphate binders are helpful in lowering phosphorus levels. Calcium carbonate and calcium acetate are some of them.
Maintaining adequate calcium levels to improve bone health:
• If calcitriol is inadequately produced by the kidney, then supplementation of synthetic calcitriol is required.
• Calcium supplements are also given to maintain bone health.