Yes, many small kidney stones cause no symptoms at all and are often referred to as ‘silent stones’. In the UK, it is common for these stones to be discovered incidentally during a scan for an unrelated health issue, such as an ultrasound or CT scan for abdominal discomfort or a routine check-up. As long as a stone remains stationary within the kidney and does not block the flow of urine, it can exist for years without the person ever knowing it is there. However, even a very small stone can cause excruciating pain the moment it shifts and enters the narrow drainage tubes.
What We will cover in this Article
- The definition and discovery of ‘silent stones’
- Why location is more important than size for pain
- How a tiny stone can remain undetected for years
- The triggers that turn a silent stone into a symptomatic one
- A data table of stone size vs. the likelihood of symptoms
- UK clinical advice on managing incidentally found stones
The Concept of the ‘Silent Stone’
A kidney stone only causes pain when it creates an obstruction or irritates the sensitive lining of the urinary tract. The internal chambers of the kidney (the calyces) have a relatively large volume compared to the ureter (the tube that carries urine to the bladder).
If a small stone typically less than 4mm is sitting quietly in one of these lower chambers, it may not interfere with the kidney’s function at all. Because it isn’t blocking the flow of urine, there is no pressure build-up (hydronephrosis), and therefore no ‘renal colic’ pain. Many people in the UK carry these stones for decades, and they are only found when a person has an imaging test for something else, like a suspected gallstone or a pulled muscle.
- No Obstruction: Urine can flow around the stone freely.
- No Inflammation: The stone is not moving enough to scrape the kidney’s lining.
- Incidental Finding: Discovery occurs by chance during unrelated medical imaging.
When Size Doesn’t Matter: The Role of Location
A common misconception is that larger stones always hurt more. In reality, a massive 15mm stone that is ‘fixed’ in a corner of the kidney might cause no pain, while a tiny 2mm stone can cause a medical emergency if it gets stuck in the ureter.
Once a small stone moves out of the kidney and enters the ureter, the situation changes instantly. The ureter is a narrow, muscular tube only a few millimetres wide. Even a very small stone can cause the tube to spasm or block the flow of urine entirely. This leads to the characteristic ‘waves’ of intense pain that radiate from the back to the groin. Therefore, a stone’s ‘silence’ is entirely dependent on its current position within the renal system.
- Renal Pelvis: Stones here can grow quite large without causing symptoms.
- Ureteric Junction: This is the most common ‘choke point’ where silent stones become painful.
- Bladder: Once a stone reaches the bladder, the intense pain often subsides, leaving only minor irritation.
Triggers: Why Silent Stones ‘Wake Up’
While a stone can be asymptomatic for years, several factors can cause it to shift, leading to a sudden ‘attack’.
The most frequent trigger is a change in hydration. A sudden increase in fluid intake can increase the volume and pressure of urine behind the stone, physically pushing it out of its quiet corner. Conversely, severe dehydration can cause the kidney to contract, dislodging a stone. Jarring physical activities such as running, jumping, or even a bumpy car ride can also provide enough mechanical force to move a stone from the kidney into the drainage system.
- Hydration Spikes: Changes in urine flow can ‘flush’ a stone forward.
- Physical Movement: High-impact exercise can dislodge small stones.
- Gravity: Simply changing sleeping positions or standing for long periods can shift a stone’s position.
Data Table: Stone Size vs. Symptom Likelihood
The following data represents the typical clinical profile of patients in the UK based on the size of the stone when it is first discovered.
| Stone Size | Likelihood of Being ‘Silent’ | Chance of Passing Naturally | Clinical Action |
| <3mm | Very High | ~90-95% | Observation / Hydration |
| 3mm – 5mm | Moderate | ~70% | Medical Expulsive Therapy |
| 5mm – 7mm | Low | ~40-50% | Possible Lithotripsy |
| >7mm | Very Low | <20% | Surgical Intervention |
To Summarise
Small kidney stones frequently cause no symptoms at all as long as they remain stationary and do not obstruct the flow of urine. These ‘silent stones’ are often discovered by chance during scans for other conditions. While they are harmless in their stationary state, they represent a ‘potential’ for future pain if they shift into the narrower parts of the urinary tract. In the UK, if a silent stone is found, the usual advice is to increase hydration to prevent it from growing and to monitor for any sudden changes in comfort.
If you experience severe, sudden, or worsening symptoms, such as intense pain in your side, blood in your urine, or a high fever with chills, call 999 immediately.
How many people have ‘silent’ stones without knowing it?
Estimates suggest that a significant minority of the UK population may have small, asymptomatic stones that are never diagnosed unless they move.
If a scan finds a silent stone, should I have it removed?
In most cases, UK clinicians prefer ‘watchful waiting’ for small, silent stones, as the risks of surgery may outweigh the benefits if the stone isn’t causing trouble.
Can a silent stone damage my kidney?
Generally, no. As long as the stone isn’t blocking urine flow or causing recurring infections, it is unlikely to cause long-term renal damage.
Do silent stones eventually grow?
They can. If the underlying chemical imbalance in your urine isn’t corrected through hydration and diet, a small silent stone can gradually become a large symptomatic one.
Is blood in the urine a sign of a silent stone?
Sometimes. Even if there is no pain, a stone can occasionally scrape the kidney lining, causing ‘microscopic’ blood that only shows up on a dipstick test.
Can I dissolve a silent stone so it never hurts?
Most stones (calcium oxalate) cannot be dissolved. However, uric acid stones can sometimes be dissolved with medication, preventing a future attack.
What should I do if my GP finds a silent stone?
The most important step is to significantly increase your daily water intake to ensure the stone stays small and has a better chance of passing easily if it does move.
Authority snapshot
This article was reviewed by Dr. Stefan Petrov, a UK-trained physician with an MBBS and postgraduate certifications including ACLS and BLS. Dr. Petrov has extensive experience in the NHS, particularly in interpreting diagnostic imaging and managing patients with incidentally discovered urological issues. This guide follows the standards set by the British Association of Urological Surgeons to provide clear, evidence-based information on asymptomatic renal stones.
