- Heredity: Some people are more susceptible to forming
kidney stones, and heredity certainly plays a role. The majority of 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 may be passed on from generation to generation. Some rare
hereditary diseases also predisposecystine (an amino acid), oxalate, (a
type of salt), and uric acid (as in gout).
some people to form kidney stones. Examples include people with renal tubular acidosis and people with problems metabolizing a variety of chemicals including
- Geographical location: There is also a geographic predisposition in some people who form kidney stones. There are regional "stone belts," with people living in the Southern United States, having an increased risk. This is likely because of the hot climate, since these people can get dehydrated, and their urine becomes more concentrated, allowing chemicals to come in closer contact and begin forming the nidus of a stone.
- Diet: Diet may or may not be an issue. If a person is susceptible to forming stones, then foods high in calcium may increase the risk, however if a person isn't susceptible to forming stones, nothing in the diet will change that risk.
- OTC products: People taking diuretics (or "water pills") and those who consume excess calcium-containing antacids can increase the amount of calcium in their urine and increase their risk of forming stones. Patients with HIV who take the medication indinavir (Crixivan) can form indinavir stones.
- Renal colic (renal is the medical term for things related to the kidney) has a classic presentation when a kidney stone is being passed.
- The pain is intense and comes on suddenly.
- It is usually located in the flank or the side of the mid back and radiates to the groin. Those affected cannot find a comfortable position, and many writhe in pain.
- This is opposed to non-colicky type pain, like appendicitis or pancreatitis, where movement causes increased pain and affected persons hold very still.
- Sweating, nausea and vomiting are common.
- Blood may be visible in the urine because the stone has irritated the ureter. Blood in the urine, however, does not always mean a person has a kidney stone. There may be other reasons for the blood, including kidney and bladder infections, trauma, or tumors. Urinalysis with a microscope may detect blood even if it is not appreciated by the naked eye. Sometimes, if the stone causes complete obstruction, there may be no blood in the urine because it cannot get past the stone.
- The classic presentation of renal colic associated with blood in the urine suggests the diagnosis of kidney stone. Unfortunately, many other conditions can mimic this disease, and the physician or healthcare provider may need to order tests to confirm the diagnosis. There should always be a concern about the possibility of a leaking abdominal aortic aneurysm when dealing with a patient who presents with the typical symptoms of a kidney stone.
- Physical examination is not very helpful in patients with kidney stones, aside from the finding of flank (side of the body between the ribs and hips) tenderness. The examination is often directed to ensuring that other potentially dangerous diagnoses don't exist. As examples, when examining the abdomen, the physician will be looking for a palpable mass that pulsates, which may be a sign of an aneurysm. Tenderness under the right rib cage margin may signal gallbladder disease.
- Symptom control is very important, and medication for pain and nausea may be provided before the confirmation of the diagnosis occurs.
- A urinalysis will show whether there is blood in the urine. It is also done to ensure that there is no infection associated with the kidney stone.
- Blood tests are usually not done, except when the physician has concerns about the diagnosis or is worried about kidney stone complications.
- CT scanning of the abdomen is the diagnostic test of choice. It is done without asking the patient to drink contrast material to outline the bowel and without intravenous dye injection. The scan will show the anatomy of the kidneys, ureter, and bladder and will show if a stone exists, how big it is, and how much blockage it is causing. The CT also demonstrates many other organs in the abdomen, like the appendix, pancreas, and aorta and may give extra information in case the preliminary diagnosis of kidney stone was wrong.
- Ultrasound is another way of looking for kidney stones and obstruction and may be useful when the radiation risk of a CT scan is unwanted (for example, if a woman is pregnant).
- In those patients who already have the diagnosis of a kidney stone, plain abdominal x-rays may be used to track its movement down the ureter toward the bladder.
- Since most patients have two kidneys, a temporary obstruction of one is not of great significance. For those patients with only one kidney, an obstructing stone can be a true emergency, and the need to relieve the obstruction becomes greater. A kidney that remains completely obstructed for a prolonged period of time may stop working.
- Infection associated with an obstructing stone is another emergent situation. When urine is infected and cannot drain, it acts like an abscess and can spread the infection throughout the body (sepsis). Fever is a major sign of this complication, but urinalysis may show an infection and cause the urologist to act to place a stent or remove the stone.
- For the first-time kidney stone patient, there should be an attempt to catch the stone by straining the urine, so that it can be sent for analysis. The stone may be so tiny that it may not be recognized. While most stones are made of calcium oxalate, should that not be the case, knowing what type of stone is the culprit may be helpful in preventing further episodes. For those whose stone disease is recurrent and the kind of stone is known, this instruction is omitted.
- Drinking plenty of water will help push the stone down the ureter to the bladder and hasten its elimination.
- A follow-up visit with a urologist will be arranged one to two weeks after the initial visit, allowing the stone to pass on its own.
- Patients should call their physician or return to the emergency department if the pain medication is not working to control the pain, if there is persistent vomiting, or if a fever occurs.
- While kidney stones and renal colic probably cannot be prevented, the risk of forming a stone can be minimized by avoiding dehydration. Keeping the urine dilute will not allow the chemical crystals to come out of solution and form the nidus of a stone. Making certain that the urine remains clear and not concentrated (yellow) will help minimize stone formation.
- Medication may be prescribed for certain types of stones, and compliance with taking the medication is a must to reduce the risk of future stone episodes.