Portuguese version: CĂLCULO RENAL (PEDRA NOS RINS)
Do you know what causes kidney stones? What are the symptoms?
kidney stones, also known as nephrolithiasis or urolithiasis, is a very common disease, affecting 5% of world population. If the UTI is more common in women, the stones affects mainly men
To Understand how a kidney stone is formed is crucial to learn how to prevent new cases.
Over 80% of stones are composed of calcium salts, mainly calcium oxalate and calcium phosphate. Other less frequent types are uric acid (read: GOUT AND URIC ACID), struvite (magnesium ammonium phosphate), and cystine stones.
What causes kidney stones ?
Imagine a glass of water. Pure water is clear and transparent. Now, if you throw some salt in the water, it will dilute and disappear. If you keep throwing more and more salt, the water becomes cloudy to point where the salt begins to precipitate at the bottom of the cup. This happens when the amount of solvent (water) is not sufficient to dissolve all the solute (salt). Every solute needs a specific amount of water to stay soluble
This is the principle of formation of the kidneys stones. When the amount of water in urine is not sufficient to dissolve all the salts present, they return to their solid form and precipitate along in the urinary tract.
Therefore, to simplify a complex process, we can say that the formation of calculi occurs when there is lack of solvent (water), excess of solute (salt), or even both. The substances not diluted form crystals, which become anchored in the kidney and gradually increase in size, forming a kidney stone.
Now, that is not difficult to understand why the majority of kidney stones occur due to little intake of fluids. People with a family history of nephrolithiasis should urinate at least 2L per day. It is not practical to measure your daily urine., so a simple tip is to watch the color of the urine. A well diluted urine is bright yellow, almost transparent like water (read: CHANGES IN URINE COLOR )
A diluted urine solves the problem of most people with kidney stones. However, there is a group of patients that even drinking plenty of water, continues to form stones. Those are the ones with disturbances in their urinary composition. They have excess of solutes in their urine.
This is the most important concept of the text. Everyone with more than 1 episode of kidney stone should be investigated for metabolic disorders that cause excess solute in the urine.
If you have recurrent nephrolithiasis and had never investigated the etiology, it’s time to look for a nephrologist. Depending on your problem, there are drugs that can prevent new stones.
Sometimes, a simple change in your diet can prevent the appearance of new stones. You might be thinking: OK, if the stones are formed mainly by calcium, and you are saying that excess of solute causes kidney stone, so, all I have to do is consume less calcium. That’s well thought, but that’s wrong.
The excess of calcium in the urine has nothing to do with your diet. It’s an intrinsic problem of the kidneys. Now imagine, if you are losing calcium in the urine, and you are not consuming enough to replace it, what do you think will happen? That’s right, your blood calcium will be low and your body will start to take calcium off your bones to maintain a desirable level.
So, if you have recurrent kidney stones, you should start drinking more water while you wait for your appointment with a nephrologist
Recurrent kidney stones are one of the most common causes of chronic renal failure. Therefore, it is not just a matter of dealing with the pain, you can actually lose your kidney if don’t seek for help.
What are the symptoms of a kidney stone?
Symptoms of a kidney stone usually occur when the stone passes from the kidney into the ureter (the tube that leads from the kidney to the bladder). Excruciating back pain, blood in the urine (hematuria), passing small stones in the urine, nausea or vomiting, and the urgent need to urinate are common symptoms of kidney stones.
The pain is usually described as the worst the patient ever had. It starts in the back and irradiates toward the groin. Typically, the pain waxes and wanes in severity. Waves of severe pain, known as renal colic, usually last 20 to 60 minutes, although less severe pain can be present between episodes of renal colic.
Fever is not an expected symptom and its presence suggests an associated infection.
Many patients with kidney stones have no symptoms at all. The stones are accidentally found when an imaging study (such as an ultrasound, x-ray or CT scan) is performed for other purposes.
How to diagnose a kidney stone?
Clinical symptoms, laboratory tests, and imaging studies are usually used to diagnose a kidney stone.
When it’s not the first stone, it’s easier to establish the diagnosis. Actually, most of the times the patients comes to the doctor already knowing the diagnosis.
CT scan , ultrasonography and abdominal x-ray are the most commons image exams performed. The former is the best one. Blood and urine tests can help in the differential diagnosis.
Kidney stone treatment
The initial treatment consists of powerful analgesics and fluids. If the stones are smaller than 0,5 cm, they might pass spontaneously within the next hours. If the stones are 1 cm or bigger, they will not pass and further treatment is required.
The options are:
- Shock wave lithotripsy (SWL)
- Percutaneous nephrolithotomy (PNL)
- Ureteroscopy
Your doctor will decide between one of them depending on your case
