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BONE HEALTH IN DIALYSIS

nephroplus | January 20, 2021

By: Apeksha Ekbote, Msc, RD, Chief Dietician, NephroPlus

Having healthy bones is essential to maintaining body structure and mobility. Calcium is a mineral that builds and strengthens bones. It’s found in many foods, particularly milk and other dairy products. If calcium levels in the blood become too low, four small glands in the neck called the parathyroid glands release a hormone called parathyroid hormone (PTH). This hormone draws calcium from the bones to raise blood calcium levels. Too much PTH in the blood will remove too much calcium from the bones; over time, the constant removal of calcium weakens the bones.

Phosphorus, which is found in most foods, also helps regulate calcium levels in the bones. Healthy kidneys remove excess phosphorus from the blood. When the kidneys stop working normally, phosphorus levels in the blood can become too high, leading to lower levels of calcium in the blood and resulting in the loss of calcium from the bones.

Healthy kidneys also produce calcitriol, a form of vitamin D, to help the body absorb dietary calcium into the blood and the bones. If calcitriol levels drop too low, PTH levels increase, and calcium is removed from the bones. Calcitriol and PTH work together to keep calcium balance normal and bones healthy. In a patient with kidney failure, the kidneys stop making calcitriol. The body then can’t absorb calcium from food and starts removing it from the bones

Renal osteodystrophy is a collective term describing the mixture of pathophysio­logical conditions that afflict the skeletal system of patients with chronic kidney disease.

It is necessary to know that bone disease in patients with CKD is usually asymptomatic, and the symptoms, if any, appear late during Renal Osteodystrophy. Patients with secondary hyperparathyroidism have a range of symptoms that affect their quality of life and daily functioning. These include:

  1. a) Musculoskeletal symptoms: Bone pain, which occurs in the low back, hips and legs and is aggravated by weigh bearing. Bone deformities are common in patients with severe hyperparathyroidism. They are due to fractures, which can lead to kypho-scoliosis or chest wall deformity.

 

  1. b) Itchy Skin/Pruritus: Itchy Skin also called as Pruritus is caused due to dryness which occurs in advanced renal failure, especially in patients on dialysis, and is possibly related to deposition of calcium and phosphorus in the skin.

 

  1. c) Cardiovascular calcification: Coronary artery calcification is commoner and more severe in patients on haemodialysis than in persons without renal failure and is probably due to excessive use of calcium-containing phosphate binders and vitamin D analogues.

Dietary treatment of Renal Osteodystrophy: – The Goal to treat renal osteodystrophy is to restore balance between calcium, PTH, phosphorus and vitamin D in the body. Restricting phosphorus intake is advisable which can be achieved by reducing intake of dairy products, certain vegetables, and colas. According to K/DOQI (National Kidney Foundation) guidelines, phosphorus intake should be restricted to 800-1000 mg daily when the serum phosphorus level is > 5.5 mg/dl in patients with CKD stage 5.

Many patients with CKD, and all dialysis patients, require administration of oral phosphate binders to limit the absorption of dietary phosphorus. Taking these medications with food is always recommended.

A good treatment program includes proper attention to dialysis, diet, and medications, which can improve body’s ability to repair bones damaged by renal osteodystrophy.High levels of Parathyroid hormone can be treated with medications.

Disclaimer: Contact your Nephrologist or Physician to know about the most suitable treatment for your condition. 

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