The kidney acts as a filter for the blood, removes waste products from the body, and produces urine.
It also helps regulate electrolyte levels that are important for body function.
Urine drains from the kidney through a narrow tube called a ureter in the bladder. When the bladder fills and there is an urge to urinate, the bladder empties out through the urethra, a tube much wider than the ureter.
In some people, the chemicals crystallize in the urine and can form kidney stones. These stones are very small when formed, smaller than a grain of sand, but can gradually grow over time to an inch or more.
Urolithiasis is the term that refers to the presence of stones in the urinary tract, while nephrolithiasis (nephro = kidney + lithiasis = stones) refers to kidney stones and ureterolithiasis refers to stones lodged in the ureter.
The size of the stone is important, but where it is and whether it blocks or prevents urine from draining can be just as important. When the stone settles in the kidney, it rarely causes pain, but when it falls into the ureter, it acts like a dam.
As the kidney continues to function and produce urine, pressure builds up behind the stone and causes the kidney to swell. This pressure is what causes kidney stone pain, but it also helps push the stone along the path of the ureter.
When the stone enters the bladder, the obstruction in the ureter is relieved and the symptoms of a kidney stone resolve.
What Causes Kidney Stones?
There is no consensus on why kidney stones form.
Some people are more susceptible to kidney stones, and heredity can play a role. Most kidney stones are made of calcium, and hypercalciuria (high levels of calcium in the urine) is a risk factor.
The predisposition to high levels of calcium in the urine can be passed from generation to generation. Some rare inherited diseases also predispose some people to kidney stones.
- People with renal tubular acidosis.
- People who have trouble metabolizing a variety of chemicals, including cystine (an amino acid), oxalate (a salt of an organic acid), and uric acid (as in gout).
There may be a geographic predisposition to form kidney stones, so where a person lives they may be more likely to form kidney stones.
There are regional “stone belts,” and people living in the southern United States are at increased risk of stone formation. The hot climate in this region combined with inadequate fluid intake can cause people to be relatively dehydrated.
This causes their urine to become more and more concentrated and allowing chemicals to come into closer contact to form the nest, or the beginning, of a stone.
Diet may or may not be a problem. If a person is susceptible to forming stones, then foods rich in animal protein and salt can increase the risk. However, if a person is not susceptible to stone formation, diet will probably not change that risk.
People who take diuretics (or “water pills”) and who consume too much antacids that contain calcium can increase the amount of calcium in their urine and potentially increase the risk of stone formation.
Taking excessive amounts of vitamins A and D is also associated with higher levels of calcium in the urine. HIV patients taking the drug indinavir (Crixivan) can form indinavir stones.
Other prescription medications commonly associated with stone formation include phenytoin (Dilantin) and antibiotics such as ceftriaxone (Rocephin) and ciprofloxacin (Cipro).
Some chronic diseases are associated with kidney stone formation, including cystic fibrosis, renal tubular acidosis, and inflammatory bowel disease.
Kidney stones in children
The appearance of a kidney stone in a child is a relatively rare event.
In countries where plants are the main source of protein in the diet, for example in Southeast Asia, the Middle East, India and Eastern Europe, the frequency of kidney disease in children is increasing. In developing countries, kidney stones made from uric acid are found more frequently.
Kidney stone symptoms in children are similar to those in an adult, although with very young children or infants, the symptoms may be more difficult to appreciate and understand. The main symptom in a baby can be intense and inconsolable crying, and the discomfort can be mistaken for colic.
Symptoms and Signs of Kidney Stones
When a tubular structure becomes blocked in the body, waves of pain occur as the body tries to unblock the obstruction. These waves of pain are called colic.
This is opposed to non-colicky pain, such as that associated with appendicitis or pancreatitis, in which movement causes increased pain and the patient tries to keep very still. kidney) has a classic presentation when a kidney stone is passed.
- The pain is intense and comes on suddenly. It can rise and fall, but there is usually significant underlying pain between acute pain spasms.
- It is usually found on the flank or side of the mid-back and can radiate to the groin. Men may complain of pain in the testicle or scrotum.
- The patient cannot find a comfortable position and often squirms or feels pain.
Sweating, nausea, and vomiting are also common symptoms.
Blood may or may not be visible in the urine because the stone has irritated the kidney or ureter. Blood in the urine (hematuria), however, does not always mean that a person has a kidney stone.
There may be other reasons for the blood, including kidney and bladder infections, trauma, or tumors. Urinalysis under a microscope can detect blood even if it is not visible to the naked eye. Sometimes if the stone causes complete obstruction, no blood can be found in the urine because it cannot pass the stone.
If an infection is present along with a kidney stone, fever and chills may occur.
How are kidney stones diagnosed?
The classic presentation of renal colic associated with blood in the urine suggests the diagnosis of kidney stones.
Many other conditions can mimic this disease, and the care provider may need to order tests to confirm the diagnosis.
In older patients, it is always important to at least consider the diagnosis of a leaky or ruptured abdominal aortic aneurysm (abnormal widening of the large blood vessel that leads from the heart to supply blood to the body) as a source of this type of pain.
Physical examination is often not helpful in patients with kidney stones, other than the finding of tenderness in the flank (side of the body between the ribs and hips). The exam is often done to look for potentially dangerous conditions.
The doctor may palpate or palpate the abdomen, trying to find a pulsating or throbbing mass that may indicate the presence of an abdominal aortic aneurysm.
Listening to the abdomen with a stethoscope may reveal a murmur or noise from abnormal blood flow through the aneurysm. Tenderness below the right margin of the rib cage may be a sign of gallbladder disease.
Lower quadrant tenderness may be associated with appendicitis, diverticulitis, or ovarian disease. Scrotal examination can exclude testicular torsion.
In children, colicky abdominal pain may be associated with intussusception.
Symptom control is very important, and pain and nausea medications may be given before the diagnosis is confirmed.
A urinalysis can detect blood in the urine. It is also done to look for evidence of infection, a complication of kidney stone disease. Sometimes crystals can be seen in the urine and can give a clue as to what type of stone might be present.
Blood tests are generally not indicated, unless the doctor has concerns about the diagnosis or is concerned about kidney stone complications.
Computed tomography (CT) of the abdomen without oral or intravenous contrast dye is the most commonly used diagnostic test. The scan will show:
- The anatomy of the kidneys, ureter and bladder,
- It can also detect a stone, its location, its size, and whether it causes ureter dilation and kidney inflammation.
- CT can also evaluate many other organs in the abdomen, including the appendix, gallbladder, liver, pancreas, aorta, and intestine.
However, since contrast material is not used, there are some limitations in the details that can be seen in the scan images.
Ultrasound is another way to look for kidney stones and obstruction and can be helpful when the radiation risk from a CT scan is unwanted (for example, if a woman is pregnant).
Ultrasound requires a specially trained person to obtain and interpret the images. That person may not always be present.
Emergency physicians are increasingly being trained to use bedside ultrasound. If ultrasound can make the diagnosis, a CT scan may not necessarily be ordered.
In those patients who already have a diagnosis of kidney stones, plain abdominal radiographs can be used to track their movement up the ureter into the bladder. CT scans should be limited to no more than one per year unless absolutely necessary to minimize radiation exposure.
What are the treatments for kidney stones?
In the emergency department, IV fluids may be given to help with hydration and to allow the administration of medications to control pain and nausea.
Ketorolac (Toradol), an injectable anti-inflammatory drug, and narcotics can be used to control pain, with the goal of alleviating suffering and not necessarily to relieve the patient of pain.
Nausea and / or vomiting can be treated with antiemetic medications such as ondansetron (Zofran), promethazine (Phenergan), or droperidol (Inapsin).
The decision to send a patient home will depend on the response to the medication.
If pain is intractable (difficult to control) or vomiting persists, hospitalization may be necessary. Also, if an infection is associated with the stone, hospital admission will be considered.
Pain management at home follows the lead of hospital treatment. Ibuprofen (OTC) over the counter (Advil) is used as an anti-inflammatory drug and narcotic pain reliever pills can be given. Anti-nausea medications can be prescribed orally or by suppository.
Tamsulosin (Flomax, a medicine used to help urinate in men with an enlarged prostate) may be used to help the stone pass from the ureter to the bladder.
Due to their size or location, some stones may not be able to pass without assistance. If the stone does not pass, then a urologist may need to use lithotripsy or shock wave therapy (ESWL) to break the stone into smaller pieces and allow those small pieces to pass more easily into the bladder.
Shock waves are a type of ultrasound that fragments stones.
If the stone is in a place where lithotripsy cannot be used, or if there is a need for emergent relief of the obstruction (an example could include the presence of an infection), the urologist may perform a ureteroscopy.
In ureteroscopy, the instruments are screwed into the ureter and may allow the doctor to use a laser to break up the stone. Occasionally, the urologist may use instruments to grasp the stone and remove it.
Home remedies for kidney stones
Prevention is always the best way to treat kidney stones. Staying well hydrated keeps urine thin and helps prevent kidney stone formation. Keeping the urine dilute is the most important intervention for stone prevention.
Those who have never had a kidney stone may not appreciate the severity of the symptoms. There is little a person can do at home to manage the debilitating pain and vomiting that can occur with a kidney stone, other than seek emergency care.
If this is the first episode and a previous diagnosis has not been established, it is important to see a doctor to confirm the diagnosis and a urologist for treatment.
For those who have a history of stones, home therapy may be appropriate. Most kidney stones will, over time, go untreated and treatment is directed at controlling symptoms.
The patient should be instructed to drink plenty of fluids by mouth. Ibuprofen can be used as an anti-inflammatory drug and for pain relief if there are no contraindications to its use.
If more pain relievers are needed, your primary care physician or urologist may be willing to prescribe stronger narcotic pain medications. Note that if fever is associated with symptoms of a kidney stone, this becomes an emergency and medical attention should be accessed immediately.
Urinary tract infections associated with a kidney stone often require urgent evaluation and may require the intervention of a urologist to remove or bypass the stone.
What are the possible complications that kidney stones could bring?
Since most patients have two kidneys, a temporary obstruction of one is not of great importance. For those patients with only one kidney, an obstructing stone can be a true emergency, and the need to relieve the obstruction increases.
A kidney that remains completely blocked for a long period of time may stop working.
Infection associated with a clogging stone is another emerging situation. When the urine is infected and cannot drain, the situation is like an abscess that can spread the infection throughout the body ( sepsis ).
Fever is an important sign of this complication, but urinalysis may show an infection and prompt the urologist to consider placing a stent, nephrostomy tube, or removing the stone to relieve the obstruction. The use of antibiotics can be considered.
What is the follow-up for kidney stones?
- For the first-time kidney stone patient, an attempt should be made to catch the stone by forcing the urine so that it can be sent for analysis.
- In addition, blood tests and a 24-hour urine collection may be done to try to determine the cause of the stone formation.
- While most stones are made from calcium oxalate, stones can also consist of other chemicals. It is possible to prevent future stone formation by taking medicine.
- Drinking lots of water will help push the stone up the ureter into the bladder and speed up its removal.
- A follow-up visit with a urologist can be arranged one to two weeks after the initial visit, allowing the stone to pass on its own.
Patients should call their doctor or return to the emergency department if pain medication does not work to control pain, if there is persistent vomiting, or if a fever develops.
How to prevent kidney stones
- While kidney stones and renal colic cannot always be prevented, the risk of forming a stone can be minimized by avoiding dehydration. Keeping the urine diluted will not allow the chemical crystals to come out of solution and form the initial nest of a stone.
- Ensuring that the urine remains clear and unconcentrated (dark yellow) will help minimize stone formation.
- Medications may be prescribed for certain types of stones, and adherence to taking medications is imperative to reduce the risk of future episodes.
- Some home remedies to prevent kidney stones may or may not work.
- Lemonade or lemon juice can help prevent kidney stone formation.
Kidney stone prognosis
Once a patient has passed a stone, there is a high probability that they will pass another stone in their life. Since kidney stones can also be inherited, this probability is passed on to the next generation.
A patient who has experienced a stone is unlikely to forget the experience and will often come to the health center that already knows the diagnosis. People with recurring stones can be given medicine to keep at home if symptoms recur.