Management of hyperphosphatemia (3D principle)

As the kidney function and glomerular filtration function of patients with chronic kidney disease (CKD) decrease, hyperphosphatemia will inevitably occur. Under normal circumstances, urinary phosphate excretion can be reduced in CKD stage 2, followed by hyperphosphatemia in CKD stage 3. Since the phosphorus in the extracellular fluid only accounts for 1% and is partially bound to proteins, its exchange with phosphorus in cells and bones is slow. Therefore, conventional hemodialysis can only remove about 800 mg of phosphorus at one time. Most hemodialysis patients currently The treatment methods, which are three times a week for 4 hours each time, cannot effectively remove blood phosphorus. For peritoneal dialysis patients, only about 300 mg of blood phosphorus can be removed every day, which is far from being able to effectively remove excess phosphorus.

Generally, we can reduce high blood phosphorus from three aspects: limiting phosphorus intake, rational use of phosphorus binders, adequate dialysis or increasing the removal of phosphorus by dialysis, which is often referred to as the 3D principle: DIET ( Diet, restriction of phosphorus intake); DRUG (drugs, use of phosphate binders); DIALYSIS (dialysis, adjustment of dialysis regimen). Let’s talk about it in detail:

Diet: Control your diet and limit phosphorus intake. For patients with CKD stages 3-5, it is recommended to consume 800-1000mg of dietary phosphorus every day, choose foods with a low phosphorus/protein ratio (phosphorus/protein ratio 12mg/g) and low phosphorus absorption rate, and limit the intake of foods containing large amounts of phosphate additives food. In addition, proper cooking methods are also one of the effective measures to reduce phosphorus. For example, blanching or boiling can remove phosphorus. The proportion of phosphorus removal is: vegetables 51%, beans 48%, meat 38%, flour Class 70% etc. In short, we should try to eat natural plant proteins and animal proteins on the basis of ensuring nutrition, and avoid foods containing a large number of additives, such as processed meat, ham, sausages, canned fish, baked foods, cola and Other soft drinks.

In terms of drugs: There are currently three types of commonly used phosphorus-lowering drugs, namely ① Calcium-free phosphorus binding agents: Aluminum hydroxide and aluminum carbonate were once widely used clinical phosphorus binding agents with low cost and The phosphorus binding rate is high, but long-term use can lead to aluminum deposition, bone disease and nervous system damage. In addition, children are prone to aluminum poisoning, so this treatment method is no longer advocated; ② Calcium-containing phosphorus binding agents: representative drugs There are calcium carbonate and calcium acetate. Taking large amounts of calcium-containing phosphate binders can cause an increase in blood calcium in CKD patients and accelerate the progression of cardiovascular and soft tissue calcification in patients; ③ New phosphate binders: representative drugs lanthanum carbonate and sevelamer , the lanthanum ions in lanthanum carbonate have a strong affinity for phosphorus, and combine with phosphorus in the intestine to form an insoluble lanthanum phosphate complex and then be excreted; while sevelamer is a cationic hydrogel polymer that passes ions The exchange effect combines with the phosphate in the intestine, thereby reducing the blood phosphorus concentration, and is not absorbed by the gastrointestinal tract, so the incidence of hypercalcemia and tissue calcification is very small, and the safety is high.

Dialysis includes hemodiafiltration, hemodialysis, peritoneal dialysis and other methods. The adequacy of blood phosphate removal by the above three methods is as follows: hemodiafiltration is the highest, hemodialysis is the second, and peritoneal dialysis is the lowest. Serum phosphorus concentration can be effectively controlled by extending the dialysis time and increasing the frequency of dialysis.

In summary, through the above methods, we can stably control the blood phosphorus level of patients with CKD hyperphosphatemia within the normal range, and improve the quality of life and survival time of the majority of kidney patients. For most patients, the choice of phosphorus-lowering method often depends on economic status. Currently, high-flux dialysis and new phosphate binders are relatively expensive. For patients with poor economic status, strengthening health education and controlling phosphorus intake are the most economical and effective ways to reduce phosphorus.