Phosphorus is present plentiful in our body next to calcium and it plays a very important role in bone metabolism energy metabolism and formation of cells. It is richly present in our teeth and bones. Our body utilizes phosphorus to keep our bones and teeth’s strong, to provide energy by helping to break down fat protein and carbohydrates, as a source to produce hormones and mainly maintain normal pH balance of our body.
Phosphorus in our bloodstream is controlled by calcium, vitamin D, parathyroid hormone and phosphorus itself with its interaction with the kidney. Phosphorus in our diet is absorbed by intestines and excreted through stools and urine by kidneys. In dialysis patients, as the kidney functions are compromised there will not be proper elimination of excess phosphorus from the body.
Excess amount of phosphorus in the blood causes the abnormal release of parathyroid hormone which weakens the bone which later develops into Renal Osteodystrophy. It also decreases the amount of calcium in the bloodstream causing calcification of tissues of the heart, skin, and lungs. Uremic Pruritus (Itching) due to phosphorus overload is also seen in many dialysis patients.
When it comes to dialysis treatment phosphorus is poorly filtered by the dialysis filter due to its vast distribution in the body and slow shift from the cells into blood vessels and to the plasma where it filters off across the dialysis membrane. This is not the only reason for it to be poorly filtered. Phosphorus even though it is of low molecular weight is coated with water particles that bind strongly to phosphorus, thus increasing its dimension which makes it more difficult to pass across the dialysis membrane.
The removal of excess phosphorus particularly in dialysis patients is indicated as highly important due to the above-mentioned disorders which can occur very swiftly in dialysis patients and it is life-threatening. Phosphorus in dialysis patients can be maintained normal or near-normal with the help of diet, medication and treatment methods.
Phosphorus is present in many foods we consume in our daily diet; it is very rich in protein-rich foods which make it very hard to manage phosphorus as dialysis patients must limit phosphorus intake despite increased demand for protein supply. And it is most commonly used as additives or preservatives which are found in canned foods, bottled drinks, ready to eat foods and most processed foods.
Cooking and boiling are some of the most effective methods of phosphorus reduction in the food, by utilizing this method sodium, potassium, calcium, etc. from the food can also be reduced. The loss of mineral is dependent on the amount of liquid used for boiling as well as on-time and degree of food shredding. Boiling meat reduces phosphorus content to a greater extent than protein content in it, but this is poorly practiced as it is time-consuming and reduces the taste of food.
To maintain normal phosphorus balance in a dialysis patient is very difficult because of the high protein requirement. But it can still be achieved with intestinal phosphorus binders. Intestinal phosphorus binders are medications that are taken along with meals and snacks. It is available in pills, chewable tablets, powders, and liquids. These intestinal phosphorus binders bind to the phosphorus in the intestine and block its absorption by the intestinal enzymes reducing its bioavailability. Even though intestinal phosphorus binders are used, a large dose of these can block dietary phosphorus up to 200 – 300 mg whereas uncontrolled phosphorus intake through diet can easily surpass 1000 – 1500 mg/day. Because of this, control in dietary phosphorus should still be stressed more even under intestinal phosphorus binders.
Phosphorus removal in dialysis treatment can be enhanced by utilizing large surface area and high permeability dialysis membrane and an increase in the dialysis session duration. Nocturnal dialysis at least three times a week said to enhance phosphorus removal along with better dialysis efficiency.
Out of all the above most importantly proper dietary and nutritional counseling place a very important role in the control and management of phosphorus in dialysis patients. Proper training and better information provided to dialysis professionals and patients will make it easier and more effective in controlling dietary phosphorus thus reducing the cost and improving the quality of life in dialysis patients.
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