In the outpatient clinic, I often encounter such patients, after taking blood tests again, the patient takes the blood biochemistry sheet and asks us, “Doctor, look, my blood calcium and blood phosphorus are normal, do I still need to take calcium carbonate?” At this time, I will feel a sense of grief and loss, so many times in the past, the big lecture, small lecture is wasted, how so many years of old patients still ask such questions. Therefore, I would like to tell you about the calcium and phosphorus metabolism in dialysis patients. In fact, this calcium and phosphorus metabolism problem is very complex, and I still do not fully understand the mystery of it, this problem is not only a bone problem, it also includes the neuroendocrine, cardiovascular system, and even connective tissue is also involved. So this disorder of calcium and phosphorus metabolism can be involved in almost all the diseases you can imagine, what skin breakdown, limb gangrene, myocardial infarction, stroke, bone fracture pain and so on and so forth. So calcium and phosphorus metabolism is a systemic disease, and these pathological changes do not appear all at once, but gradually develop over the years. You could say that calcium and phosphorus metabolism disorders are a secret agent lurking around the patient, hiding the identity of the disease until years later when it suddenly kills. Since doctors can see patients at all stages, from those who have just entered dialysis to those who have been on dialysis for 20 years, they can observe the clinical symptoms of calcium and phosphorus metabolism disorders at all different times, so they are very sensitive to this issue of calcium and phosphorus metabolism and hope that none of them will go to the final stage of the disease. However, patients do not anticipate their condition in 10 or 20 years, and always think that what doctors say is sensational and scary, so many patients do not pay much attention to this kind of embolism until they have a gangrenous limb that needs to be amputated, or a myocardial infarction but cannot be implanted with a stent, then they realize the seriousness of the problem, but usually at that time the intervention of calcium and phosphorus metabolism is no longer effective, and the calcified narrowed The vessel has already formed and cannot be recanalized. Although the principles of calcium and phosphorus metabolism are complex, clinical intervention is not very complicated. Many clinical trials have been done to answer the questions of how to treat and where to go. Most of the trials concluded that the increase of blood phosphorus is closely related to the mortality of patients (18% increase in the risk of death for every 1 mg/dl increase in blood phosphorus and 10% increase in the risk of cardiovascular death), while iPTH is a phenomenon secondary to low calcium and high phosphorus, which does not directly affect the survival of patients. Therefore, strict control of blood phosphorus and calcium becomes a top priority for treatment. As the old cliché goes, the control of blood phosphorus depends firstly on Diet, secondly on Drugs and thirdly on Dialysis, which is the 3D principle. Diet: Phosphorus is widely present in various foods, especially in nutrient-rich substances with high phosphorus content, such as egg yolk, animal offal, scaleless fish, soybean products, coarse grains, some varieties of tea, etc.. In living organisms, most of the organic forms of phosphorus are combined with proteins and other carbon-containing molecules in cells, and most of the phosphorus in plants is in the form of phytic acid, which is rarely absorbed by the body; therefore, foods rich in animal protein are the main source of phosphorus for the human body. Some people have studied the effect of food processing methods on phosphorus and found that the more complex the cooking steps, the higher the phosphorus content of the food. For example, the “old hot soup” is cooked for a long time with various phosphorus-containing seasonings, and the soup is very high in phosphorus, but the protein is lost, which is one of the least desirable diets for people with uremia. This study also tells us that if food is “watered down” before cooking, many unwanted substances such as phosphorus and potassium can be removed (although some water-soluble nutrients are also lost and can be replaced by other means). In addition, the absorption rate of phosphorus in natural foods is mostly 40-60%, but many food additives contain 100% of inorganic phosphorus to be absorbed by the body, so all kinds of cooked and packaged foods purchased outside should be avoided. To summarize, it is recommended that dialysis patients, choose natural foods (consume proteins with low phosphorus content, of which egg whites are one of the foods with high protein content with little phosphorus), make them reasonably (soak or blanch them before making, reduce various seasonings and keep the original taste of the food) and reduce phosphorus intake. The following list of some food phosphorus content (all per 100g edible part of the phosphorus content): oats 451mg, wheat 405mg, brown rice 280mg, rice (cooked) 51mg; melon seeds 984mg, dried lotus seeds 583mg, sesame 574mg, soybeans 506mg, peanuts 392mg, tofu 169mg, soy milk 40mg; white potatoes 110mg. Xm7mg; pig liver 521mg, muscle 230mg, beef 177mg, mutton 134mg, pork 123mg, pig blood 11mg; various sea fish between 200-300mg, various river fish between 100-200mg, sea cucumber 8mg; wood fungus 210mg, shiitake mushroom 190mg, spinach 36mg, eggplant 30mg, celery 23mg, White radish 11mg; black date 128mg, most of the rest of fruits are below 50mg; egg yolk 547mg, milk 85mg, egg white 12mg; yeast powder 1600mg, green tea 550mg, soy sauce 153mg. Drugs: Some patients still have high blood phosphorus no matter how strict the control diet is, it is necessary to apply drugs to control it. Since most dialysis patients have calcium deficiency, calcium carbonate, a phosphorus binding agent containing calcium, is now more widely used (another advantage is that it is cheap!) . This can have a phosphorus-lowering effect while supplementing calcium. So how does calcium carbonate reduce phosphorus? In the intestine, phosphorus in food combines with ionic calcium to form CaHPO4, which is insoluble in water and is eventually excreted from the body. To combine more phosphorus, calcium and food need to be mixed well, so doctors and nurses take great pains to tell dialysis patients to “chew calcium carbonate with meals! . And in the absence of cheaper phosphorus-binding agents, most patients need to chew calcium carbonate for life. However, calcium carbonate should not be used indefinitely to bind phosphorus in food. Excessive calcium intake can increase calcification of blood vessels or other soft tissues, causing ischemic disease in various organs. In order to solve the problem of excessive calcium intake, calcium acetate is now available on the market (self-pay, about 1,000 yuan per month), which is said to have a stronger phosphorus binding power than calcium carbonate and is less likely to cause hypercalcemia and metastatic calcification (calcification of blood vessels and other soft tissues). In recent years, metastatic calcification caused by excessive calcium intake has received increasing attention, so many calcium-free phosphorus-binding agents have been developed. These drugs have been widely used in clinical practice abroad, but in China they are still non-reimbursable self-pay drugs, which greatly limits their use. However, if you are financially able to do so, you can ask your supervising physician about lanthanum carbonate, Civalam, and iron citrate. These drugs have been used in many patients and have proven to be very effective in reducing phosphorus to the standard range and do not increase the calcium load on the body, reducing the incidence of metastatic calcification. Some other intestinal detoxification drugs, such as packaged aldehyde starch and urinary toxicity clear granules, also have some phosphorus-lowering effect. Although elevated blood phosphorus is the culprit in disorders of calcium and phosphorus metabolism, excessive PTH is also an accomplice in the overall disease process that should not be overlooked; PTH is produced as a result of low calcium and high phosphorus stimulation, and the natural role of PTH is to raise blood calcium and lower blood phosphorus to achieve homeostasis in the body. Excessive PTH causes bone (Ca10(PO4)6(OH)2) to dissolve to release calcium and phosphorus, which then tells the kidneys to work more to expel blood phosphorus. and osteoporosis. So too much PTH also needs to be controlled. In the past, when medications were limited, doctors used active vitamin D3 to inhibit PTH production, but one of the side effects of this drug is that it works in the intestine to absorb more calcium and phosphorus, which directly raises blood calcium and phosphorus (perhaps your patients’ brains are confused, that’s how complicated this thing is). By the way, Calcium D is not suitable for most dialysis patients, it is a mixture of calcium and vitamin D. It is not possible to take the two orally separately, except in isolated cases, so do not take it without permission and always Consult your doctor. However, there is a drug called Sinacace that can significantly lower PTH without the side effects of elevated calcium and phosphorus. Dialysis: Although the atomic weight of phosphorus itself is very small (only 31), phosphorus exists in the body in the form of hydrated phosphate, and the molecular weight may exceed 500 (I have consulted many articles, but there is no uniform statement, but phosphate can be bound to 12 water molecules, the molecular weight will be significantly higher), the dialysis clearance pattern is close to the medium molecular toxin, so the ordinary hemodialysis dialysis for phosphorus removal is limited. removal is limited. It is generally accepted that four exchanges of peritoneal dialysis per day can remove more than 300 mg of phosphorus, and each hemodialysis session can remove 800 mg of phosphorus, but this is not enough to remove the daily phosphorus intake of the patient (usually 1000 mg of phosphorus per day), no matter how you calculate it. Therefore, at least hemodialysis three times a week and peritoneal dialysis with 4 bags of fluid per day and nighttime abdominal storage are required to remove as much phosphorus as possible. To increase phosphorus excretion, for hemodialysis patients, high-flux filters, longer dialysis times, increased dialysis frequency, and the addition of hemofiltration or perfusion may be effective. For patients on peritoneal dialysis, it is necessary to increase the amount of dialysis fluid instilled into the peritoneal cavity in a single session, prolong the duration of abdominal storage, or combine with hemodialysis to increase the excretion of phosphorus. In addition, protection of residual kidney function can also increase phosphorus clearance, don’t underestimate this poor little kidney, its presence can greatly improve the quality of life of patients. Therefore, patients who are already on dialysis still need to protect their kidneys and cannot ignore them. They should continue to treat the original disease, continue to restrict salt and water, and try not to use nephrotoxic drugs, so as to delay the speed of kidney death. In addition, if the patient after a variety of conservative treatment methods, still can not stabilize calcium and phosphorus metabolism, control PTH, then you can only seek surgical treatment, this will be introduced in the future. This will be described later. If you have already seen dizzy, do not give me a brick, because this problem is really very complex. As long as you recognize the seriousness of the problem, it is good to cooperate with the doctors and nurses because they are the only ones who care about the patients and have professional knowledge at the same time.