When we hear about renal calculi, often they are referred to as simply being ‘kidney stones’; however did you know that there are different types of kidney stones?
When we hear about renal calculi, often they are referred to as simply being ‘kidney stones’; however did you know that there are different types of kidney stones? The type of kidney stones as well as their size, will often determine the type of treatment that you receive. A sample of the stone may be retrieved for analysis to determine the preventative measures that you should take in order to reduce your risk of developing them again in the future.
What are kidney stones?
Also known as renal calculi, kidney stones as they are more commonly referred to, form when salts in the urine form solid crystals and combine to make larger ‘stones’. They are quite common, affecting around 1 in 10 men and 1 in 35 women during their lifetime.
Once a person has had a kidney stone, the chance of developing another stone is around five to ten percent each year. Some people have recurring stones throughout their lives.
Kidney stones are usually asymptomatic to begin with, but as they grow larger with time, they may cause painful symptoms. They can block the kidney, interrupting the flow of urine, cause infection, kidney damage and in some cases even kidney failure.
Types of kidney stones
The types of kidney stones that exist are named so based upon the types of crystals that combine in order to form them. These include:
- Calcium oxalate
- Calcium phosphate
- Uric acid
- Struvite
- Cystine
You may be more likely to develop a particular type of stone based on your lifestyle, diet, or family history.
Types of kidney stones: Calcium oxalate
Calcium oxalate are the most common types of kidney stones. Calcium oxalate stones form when the urine contains a low level of citrate and a high level of calcium (and either high oxalate or high uric acid). These types of kidney stones are therefore also often linked to diets that include a large proportion of high-oxalate foods. Oxalates are compounds that occur naturally in many plant and animal products. Such foods include black tea, chocolate, some nuts, spinach, beets, and more.
For patients that continually develop calcium oxalate stones, the urologist may recommend some dietary modifications alongside medical treatment.
Types of kidney stones: Calcium phosphate
Calcium phosphate stones form when calcium combines with phosphoric acid in the urine. These types of kidney stones occur when the urine is abnormally alkaline (pH above 6.3-6.5), usually due to some abnormality in the way that the urinary system functions. There are some systemic conditions that can cause this. Calcium phosphate stones can occur simultaneously with calcium oxalate stones, too.
Types of kidney stones: Uric acid
Uric acid stones tend to be one of the types of kidney stones that are more common in men, and in people who consume a diet high in animal protein. They also tend to occur in people who don’t drink enough water, which leads to the urine becoming highly concentrated and acidic. Uric acid stones can form very quickly. They are often passed in the urine (appearing as an orangey-red gravel), but if they are retained, they can block the kidney, causing severe pain.
Types of kidney stones: Struvite
Struvite kidney stones often form as a result of certain types of bacterial infections in the urinary tract. These stones are composed of the magnesium, ammonium and phosphate. When a bacterial infection inters the urinary tract and goes unnoticed or is left untreated, very large and painful struvite stones can develop. Urinary tract infections are more common in women, due to their shorter urethra, which makes entry by bacteria more easy.
Struvite stones require prompt medical attention. If they are left untreated, they can grow very quickly, sometimes occupying the entire kidney and causing injury to it. Sepsis (entry of the infection into the patient’s bloodstream) can also occur, and this is considered a medical emergency.
Types of kidney stones: Cystine
Cystine stones develop as the result of an inherited kidney abnormality known as cystinuria. In this condition, excessive amounts of the amino acid, cystine, collect in the urine and collect to form crystals or stones. These types of kidney stones can grow large and quickly. They can be formed in the kidneys, bladder, and ureters. Patients with cystinuria generally form kidney stones throughout their lives.
Treating different types of kidney stones
Our urological specialists at Melbourne Urology Centre are highly experienced and skilled in the treatment and long-term management of all different types of kidney stones. The treatment of kidneys stones is tailored to the individual patient, depending on the type, size and number of kidney stones. Once a diagnosis is made, your doctor will advise you on which treatment approach is most appropriate and effective for your individual circumstances. If you would like to make an appointment, please contact our clinic.
Written by Dr. Shekib Shahbaz and Dr. Tony de Sousa