It is also a consensus that patients with hyperuricemia and gout need to drink more water; patients with hyperuricemia and gout need to alkalinize urine. However, under these two "consensuses", many gout patients believe that drinking soda can reduce uric acid, and many people have indeed lowered uric acid after drinking soda for a long time.
Among them, it is still in the prescription of drugs for the treatment of gout and hyperuricemia, sodium bicarbonate often appears. This has led some patient friends to think that taking sodium bicarbonate (baking soda) or drinking soda water can lower uric acid.
So, can sodium bicarbonate lower uric acid? Today I will talk about how to use this drug commonly known as baking soda.
Sodium bicarbonate, also known as baking soda, is one of the commonly used drugs for the clinical treatment of gout
<h1 class="pgc-h-arrow-right" >Why do I need sodium bicarbonate to treat gout? Or to protect the kidneys</h1>
First of all, Dr. Liu wants to tell everyone that sodium bicarbonate itself is not a drug that lowers uric acid. At present, the mainstream drugs that lower uric acid are mainly allopurinol, non-bustistat and other drugs that inhibit uric acid production, and drugs that promote uric acid excretion such as benzbromarone, in addition to labuli enzymes, Prikasy and other recombinant oxidase drugs that have not yet been listed in large quantities.
Since sodium bicarbonate cannot lower uric acid, why should many doctors use this drug in clinical treatment and prescription? Let's start with kidney damage caused by hyperuricemia and gout.
Pathology and pathogenesis of gout
01| uric acid is high and easy to cause kidney damage
Renal impairment is a common concomitant disease of hyperuricemia and gout, and the proportion of people with high uric acid and kidney disease is significantly higher than that of non-hyperuricemia. Let's look at a set of data:
About 20% of primary hyperuricemia has clinical symptoms of chronic uric acid nephropathy, 10% to 20% of gout patients have clinical nephropathy symptoms; about 25% of gout patients have urinary stones symptoms, of which about 80% belong to uric acid kidney stones; end-stage renal failure is caused by gout 0.6% to 1.0%.
Occurrence of gouty nephropathy
In other words, blood uric acid levels above 420 μmol/L are risk factors for gouty nephropathy and chronic kidney disease, and also affect the prognosis of kidney disease. Another group of studies showed that for every 60 μmol/L increase in blood uric acid levels, the risk of all-cause death from chronic kidney disease increased by 8%.
The cause of kidney damage caused by hyperuricemia and gout is mainly due to the long-term deposition of urate in the kidneys due to the long-term deposition of urate in the kidneys, crystallization and kidney damage dominated by renal interstitial inflammation, such as uric acidic kidney stones, interstitial nephritis, acute and chronic renal failure. If you want to alleviate kidney damage, then preventing the deposition of urate in the kidneys is the key.
Deposition of kidney stones in the kidneys
02| alkalizing urine prevents urate deposition in the kidneys
How can we prevent the deposition of urate in the kidneys? The use of drugs and other norms for the treatment of uric acid reduction is of course the focus. However, while treating hyperuricemia and gout, clinicians have noticed the characteristics of uric acid: uric acid is a weak organic acid, which exists in two forms of free uric acid and uric acid; uric acid, as a weakly acidic substance, is not easy to dissolve in an acidic environment, and can be converted into urate with higher solubility in an alkaline environment.
Relationship between undissolved uric acid and total uric acid and urine pH
When is uric acid easily dissolved and excreted from the urine, reducing kidney damage caused by uric acid deposition? Let's look at the physiological situation of the human body pH of 7.35 ~ 7.45, this range of sodium urate in the blood and tissue fluid solubility of 380 μmol / L. Most patients with gout and hyperuricemia have a significantly lower pH in their blood and tissue fluids. Or continue with another set of data:
When the pH of urine drops to 4.75, more than 90% of uric acid will form urate crystals and cause kidney damage in kidney deposition; when the urine pH rises from 5.0 to 7.0, the solubility of uric acid in the urine can increase by 20 times; the lower the pH of the urine, the higher the incidence of renal uric acid stones.
Such data tells us that for normal people, weakly acidic urine is not harmful; but for friends with high uric acid, weak acidity of urine can create conditions suitable for urate deposition in the kidneys.
That is to say, the basis of the doctor's recommendation of alkalized urine is that the pH of the urine of patients with hyperuricemia and gout is acidic, and the alkalinized urine is mainly to prevent the precipitation and deposition of uric acid.
Patients with high uric acid tend to have lower urine pH than normal
<h1 class= "pgc-h-arrow-right" > not everyone needs to alkalize urine, nor can it alkalinize urine endlessly</h1>
Almost all patients with untreated gout have a urine pH of less than 5.5. So how do I check the pH of my urine? Generally speaking, it can be detected on a routine urinalysis test. In patients with gout, there is generally no change in the urinalysis in the early stages of the disease, and if the kidneys are involved, proteinuria, hematuria, and thick urine can be found, and the urine pH is within 5.0 to 7.0. Urine pH can be detected at home using test strips.
Since gout patients need to alkalize urine, how should they alkalize urine? There are two questions before us: Do all patients with hyperuricemia and gout need to alkalinize urine with sodium bicarbonate? Is it that the higher the pH of the urine and the higher the alkalinity of the urine, the better? Let's take a look at them one by one.
A urine routine test can detect the pH of the urine
01｜吃苯溴马龙需碱化尿液
First of all, after checking the urine pH, if the urine pH < 5.5, it may be caused by an increase in uric acid concentration; if further examination proves that the uric acid production in the body is increased, then it is necessary to use a low-uric acid drug that inhibits uric acid production; if the examination finds that the proximal renal tubule has too much reabsorption of uric acid or a decrease in secretory function, then drugs that promote uric acid excretion such as benzbromomarone are needed.
Secondly, when the patient has urinary urate stones or uses drugs that promote uric acid excretion, alkalized urine therapy is required, which is the current consensus of the rheumatic immunology community; then the common clinical situation is that when the urine pH is found to be less than 6.0, it is also necessary to appropriately alkaline urine therapy.
The transport mechanism of uric acid in the kidneys and intestines of the human body
02| the pH of alkalized urine has a range
It is not that the higher the pH of the urine, the easier the uric acid is excreted from the urine. Many people have not paid attention to this problem, but some people will be complacent after the long-term use of baking soda has dropped the blood uric acid value. In general, when the urine pH is higher than 7.0, it is true that urate stones are not prone to occur, but the following conditions also occur.
That is, after excessive alkalinization of urine, it is easy to form other types of kidney stones such as calcium oxalate, calcium phosphate, and calcium carbonate; or it will form a phosphate shell on the surface of uric acid stones that have already appeared, preventing the dissolution of urate stones or leading to the appearance of mixed stones.
Kidney stones include other types of stones in addition to urate stones
That is to say, even if alkalinization of urine is required, the pH of the urine cannot be too high or too low. When the urine pH is maintained between 6.2 and 6.9, the incidence of both urate stones and calcium stones is low; that is, this value can both increase the solubility of urate and the risk of other types of stones.
It should be noted here that the use of sodium bicarbonate alkalized urine can increase the solubility of uric acid to a certain extent and promote the excretion of uric acid. That is to say, sodium bicarbonate has a certain uric acid-lowering effect on the side, but this effect cannot be used in the "frontal battlefield" of fighting gout.
Factors associated with hyperuricemia
< h1 class = "pgc-h-arrow-right" > even if gout patients need to alkalize urine, sodium bicarbonate can not be used casually</h1>
If clinicians feel that patients with gout and hyperuricemia need to alkalize urine, of course, they will write down the relevant drugs on the prescription; but the drugs that alkalinize the urine are not only sodium bicarbonate, but also drugs such as sodium bibrate; but sodium bicarbonate (baking soda) is a commonly used clinical drug.
Indications and precautions for drugs that mainly alkalinize the urine
As I said earlier, alkalizing urine is to maintain the urine pH between 6.2 and 6.9, and not to overly alkalinize. So let me talk about what other things to pay attention to or easily ignore after alkalizing urine after following the doctor's instructions:
01| pay attention to gastrointestinal reactions: sodium bicarbonate is excreted by the kidneys in the form of bicarbonate, and can also be excreted from the lungs in the form of carbon dioxide; after taking sodium bicarbonate, carbon dioxide is produced in the stomach, increasing gastric pressure, easy to appear belching, acid reflux, bloating and other symptoms, but also aggravate gastric ulcers, resulting in gastric perforation. Therefore, long-term use should pay attention to gastrointestinal reactions, and gastroparesis, stomach pain is unknown, upper peptic ulcer, upper gastrointestinal bleeding and recent gastrointestinal surgery patients should not be used or used with caution.
Sometimes sodium bicarbonate is also required for high stomach acid
02| pay attention to electrolyte disorders: long-term large-scale use, can cause alkemia and electrolyte disorders, so there is sodium retention, congestive heart failure, edema and renal insufficiency should be used with caution; increased sodium load when hypertensive patients take it can easily lead to further increased blood pressure, so we must pay attention to the control of blood pressure; even if sodium bicarbonate is not used and sodium potassium bi citrate and other drugs are used, we must also pay attention to serum potassium concentration to prevent hyperkalemia.
Patients with chronic kidney disease and gout need to pay attention to the use of the drug
03| pay attention to uric acid-lowering drugs: after alkalizing urine, uric acid-lowering drugs can not be taken casually, and in some cases it is not recommended to use drugs that promote uric acid excretion, such as patients with chronic kidney disease stage 3 and above, it is generally recommended to use xanthine oxidase inhibitors such as allopurinol and non-busta, rather than using drugs that promote uric acid excretion such as benzbromarone.
The mechanism of action of the three major uric acid-lowering drugs
04| pay attention to daily diet: in general, alkalizing urine is to facilitate uric acid excretion to avoid uric acid deposition in the kidneys, then it is also necessary to drink more water, to maintain the daily urine output of more than 2000ml; drinking water should not be over-drinking, each time drinking water is about 200 ~ 250ml, take small sips of water; and the use of sodium bicarbonate needs to avoid taking with a large amount of milk and dairy products to prevent the occurrence of lactic alkali syndrome.
The types of medicines that require more water to drink when taking them, and the representative drugs
05| pay attention to the use of soda: soda water can also alkalinize urine, but it is not as strong as sodium bicarbonate. And many sodas are carbonated drinks that contain carbon dioxide rather than sodium bicarbonate; in addition, some sodas contain fructose, sweeteners or flavors, which can actually cause elevated blood uric acid. If you want to drink soda, it is recommended to use natural soda water, and it is not suitable for long-term use like sodium bicarbonate.
Not all sodas contain sodium bicarbonate
All in all, sodium bicarbonate is an auxiliary drug to reduce uric acid, it is generally recommended to be taken after dinner, and it is not advisable to take any drugs within 1 to 2 hours after oral sodium bicarbonate tablets; and while using sodium bicarbonate, it is also necessary to often measure the urine pH and adjust the drug according to the change of pH.