Coronavirus Disease 2019: Facts sheet to stay safe from the outbreak   Learn More

How Big are Kidney Stones?

Aastha Kapoor   by Aastha Kapoor, MS, Biotechnology    Last updated on March 4, 2020,

Contents:

 

Kidney Stones (Renal Calculi)

Kidney stones are hard substances formed within the urinary system. They are also referred as Nephrolithasis. Stones are formed due to decrease in urine volume or accumulation of unwanted toxic substances. Dehydration is the major cause of occurrence of kidney stones. Renal Calculi have a highly distant physical appearance.

 

Size of kidney stones

Kidney stones are of variable sizes. They range from small sized crystals (small kidney stones) to large sized stones (large kidney stones) such as the size of a golf ball. Variations in sizes of kidney stones affect the following things:

 

Treatment of kidney stones

The size of kidney stones affect the treatment method required for their removal. Small-sized stones can easily pass through the kidney without any medical assistance but large-sized stones require medical intervention. Certain tests are conducted which help in determining the size of kidney stones, such as KUB, an Ultrasound or an IVP. They help in analyzing which treatment should be effective for the removal of your kidney stones.

 

“It is estimated that one in ten people will have a kidney stone sometime in their lives. The prevalence of kidney stones has increased significantly in the United States from 3.8% in the late 1970s to about 9% in the 2000s. The lifetime risk of developing kidney stones is about 19% in men and 10% in women.”

 

Time needed for passing kidney stones

The size of kidney stones determine the time needed for their removal from the kidneys. Smaller the size of a stone, the faster it can pass through the urinary tract. For example, a 2mm stones may pass through the kidneys in about 12 days but stones of size 4mm can take about 30 days to pass out.

 

Read about passing of the kidney stones in urine.

 

Composition of kidney stones

The size of the stones can also indicate the compounds they are made of. Kidney stones can have a variety of compositions such as calcium, uric acid, struvite and cystine stones. They are formed by deposition of toxic compounds in the kidneys. An increased deposition of toxic compounds may result in the formation of large-sized kidney stones, which can cause blockage in the urine path.


Here is a chart that indicates the types of kidney stones and their shapes/sizes.

Type of stones Incidence rate Shape Cause Clinical risk factors
Calcium oxalate About 80% Envelop Increased calcium and oxalate in urine Higher chances in middle age men than women
Calcium phosphate < 5% Amorphous Increased calcium and pH Hyperparathyroidism and renal tubular acidosis
Uric acid About 10% Diamond or rhomboid Increased uric acid and pH of urine Gout and diabetes mellitus
Struvite About 10% Coffin-lid Increased  pH of urine Neurogenic bladder and other anatomic abnormality
Cystine < 1% Hexagonal Rare genetic disorder: increased cystine in urine  

stone types

Can small kidney stones pass naturally?

Kidney stones of less than 5mm are considered to be small. Small kidney stones can easily pass through the urinary tract without any medical assistance. 4mm size stones have 80% chances to pass through the kidneys in about a month, but 5mm size stones have 60% chances of passage in about 45 days.

To pass small-sized kidney stones naturally in urine, certain home remedies can be helpful such as increased fluid intake, increased water, lemon and citrus juice consumption and low salt, calcium and protein diet. High water concentration does not allow growth of kidney stones and they can slowly pass along with the urine. Read about passing of kidney stones with urine.

If you experience any pain in the lower abdomen during passing of the kidney stones, you can take an analgesic such as ibuprofen or any other painkiller as suggested by the doctor. Painkillers help in relieving pain and also speed up the process of passing the stone. Read about relieving kidney pain.

 

How big are kidney stones? How can they be removed?

Have you ever wondered how big are kidney stones? Stones of > 5mm size are considered as large kidney stones.

Large-sized stones cannot pass through the kidneys without any medical intervention. If they are left to pass on their own, they may take longer time, about a year or more than that and there is a risk of complications. Large sized stones may get struck in the urinary tract and cause extreme pain and bleeding during urination.

The methods involved in the removal of large-sized kidney stones are as follows:

Extracorporeal shock wave lithotripsy (ESWL)

Extracorporeal shock wave lithotripsy is the most common method for the treatment of stones which cannot pass through the urine. This involves administration of ultrasound (high-frequency sound waves), which results in breakdown of the stones into smaller pieces so they can easily pass along with urine.

lithotripsy

Ureteroscopy

Ureteroscopy is also known as retrograde intrarenal surgery (RIS). When large-sized kidney stones get struck in the ureter, ureteroscopy may be carried out.

This involves inserting a ureterscope (long, thin telescope) through urethra into the bladder, to the site where the stone got struck in the ureter. Your surgeon may remove the stone using another instrument or by laser energy, which breaks the stone into smaller pieces and allow it to pass naturally through the kidneys.

Percutaneous nephrolithotomy (PCNL)

Percutaneous nephrolithotomy is suitable for removal of extremely large-sized stones and for obese people. This involves passing a nephroscope (thin telescopic instrument) into the kidneys through a small incision in the back. The stone is then either pulled out or broken into small pieces by pneumatic energy.

Open Surgery for kidney stones removal

Open surgery is carried out in rare cases, either when you have a huge stone or abnormal anatomy. This involves an incision to be made in the back to provide access to your ureter or kidneys from where the stone can be easily removed.

 

What is a kidney stone size chart?

Kidney stones vary in sizes. Therefore, as discussed above, the composition, their treatment and removal, time they take in passing through the urine, and their other characteristics may also vary based on their sizes. A kidney stone size chart is an easy way to tabulate and illustrate the important pieces of information about one or more of these factors associated with varying sizes of kidney stones.

A kidney stone size chart may show a correlation between possible treatment options and various sizes of the kidney stone. Another type of a kidney stone size chart may show correlation between kidney stone sizes and their compositions and so on.

 

Kidney stone size chart and its features

This is a simple kidney stone size chart that that provides important information about the chances of passing stones naturally, time taken, and treatment required for various sizes of the kidney stones. More types of kidney stone charts can be possible to show different types of information pieces about kidney stones and their sizes.

Size of kidney stones Chances of passing naturally Time required to pass naturally Treatment
Less than 2mm About 80% 8 days (average) Home remedies
2-4 mm About 80% 12 days (average) Home remedies
4mm About 80% 31 days (average) Home remedies
4-7mm About 60% 45 days (average) Home remedies and painkiller
Larger than 7mm About 20% 12 months (average) Ureteroscopy
1-2cm Cannot pass   Lithotripsy
Larger than 2cm Cannot pass   Percutaneous nephrolithotomy

 

Frequently Asked Questions

The size of your kidney depends on the size of your body. The normal size of an adult human kidney is 10-13cm (4 to 5 inches). A normal adult male kidney is at least 11 centimeters long and a normal adult female kidney is at least 10 centimeters long. The right kidney is slightly longer than the left in general, but some people are born with a larger left kidney than their right kidney. The difference in their sizes is generally less than 1 cm.

Yes, kidney stones larger than 2 cm are considered big and cannot pass on their own. Based on their size, they may have difficulty moving through the urinary tract out of the body. Shock Wave Lithotripsy (SWL) is a procedure used by doctors to treat stones in the kidney and ureter that are big in size. The procedure involves breaking the bigger stones into smaller crystals which can then easily pass through urine.

Kidney stones smaller than 4 millimeters (mm) are considered as normal in mm. They can pass on their own. It takes about 31 days for these small stones to pass on an average. It is generally safe to wait four to six weeks for these small-sized kidney stone to pass out of the body. If they still cause problem and do not pass out, your doctor may recommend other procedures to remove them.

Kidney stones not kill by themselves but they can cause problems and complications which may kill someone if not treated quickly. For example, the stones may obstruct the kidneys which may cause the urine to become so infected that the bacteria gets into the blood stream and gets all over the body. This is called sepsis. It can also kill someone by blocking the ureter in a person who has only one kidney. There can be other ways in which the stones can damage your kidneys.

Kidney stones start small in size in the beginning but can grow larger in size. They can fill the inner hollow structures of your kidneys as they grow in size if they are not removed. This may lead to severe complications. It is recommended to contact your doctor if you feel you may have have a stone in the kidney or if you are at high risk of them so they can be prevented or removed in early stages when they are small.