Kidney stones (urinary stone disease) are one of the most common reasons people see a urologist. Once you have had one, the chances of forming more are high unless the cause is looked into.
This is a plain-English guide to what they are, the symptoms they cause, when to seek urgent help, the treatments available today and how to prevent them.
What is a kidney stone?
It is a solid deposit that forms when certain substances in the urine (calcium, oxalate, uric acid and others) become concentrated and crystallise. A stone can sit in the kidney for years without causing symptoms, or it can break loose and move into the ureter, the tube that carries urine from the kidney to the bladder. That is usually where the trouble starts: if the stone blocks the flow of urine, pain follows.
Not all stones are the same. They vary in size, position and composition, and those three factors determine the most suitable treatment in each case.
Symptoms: renal colic
The classic symptom is renal colic: severe pain that starts in the lower back or side and can spread towards the abdomen and groin. It tends to come in waves, is not relieved by changing position and often comes with:
- Feeling sick or vomiting.
- Needing to pass urine often and urgently.
- Blood in the urine (visible, or only picked up on a urine test).
- Stinging or discomfort when passing urine.
Not every stone causes pain. Some are found by chance on an ultrasound or CT scan done for another reason.
When to go to A&E
Most episodes of renal colic can be managed with pain relief and follow-up. But some situations need urgent attention, because they can put the kidney at risk or turn into a serious infection. Go to A&E (Urgencias) if the pain comes with any of these:
- A high temperature or shivering. A stone that causes a blockage and becomes infected is a medical emergency.
- Vomiting that stops you keeping down fluids or your medication.
- Pain that does not ease with ordinary painkillers.
- Not passing any urine, or a stone in someone who has only one kidney.
If you are in any doubt about these signs, do not wait: a blockage combined with an infection needs treating without delay.
How kidney stones are diagnosed
Diagnosis is based on your medical history, a urine test and a scan. Today the test of choice to confirm a stone, measure it and pinpoint its position is a CT scan without contrast, although ultrasound is very useful as a first look and for follow-up, especially when it is better to avoid radiation.
Knowing the stone’s exact size, its position and, where possible, its composition matters a great deal. It is the basis for deciding whether to wait for the stone to pass on its own or to treat it, and which technique to use.
Treatment options
Today the vast majority of stones are treated without open surgery, using minimally invasive techniques. The choice depends on the size, position and hardness of the stone and on the individual patient.
1. Monitoring and medication
Small stones in the ureter, especially in its lowest part, often pass on their own. In these cases the approach may be to wait, control the pain and, for selected stones, help the stone pass with medication. It is a sound and common option when the stone’s size and position allow it.
2. Shockwave lithotripsy (ESWL)
ESWL breaks the stone up from outside the body, using shock waves aimed precisely at it. The fragments, now small, then pass naturally in the urine.
It is the least invasive technique of all: it is done as a day case, with no incisions and usually without a general anaesthetic. It is a first-line option for many small kidney stones and for selected stones in the ureter. On the other hand, how well it works depends on the size and hardness of the stone, and in some cases more than one session may be needed.
You can read more about how it is done on my shockwave lithotripsy page.
3. Endoscopic surgery: ureteroscopy and RIRS (laser)
When the stone is larger, harder or in a position less suited to lithotripsy, it can be treated from the inside, with no incisions at all, by passing a very thin scope up through the urinary tract, the body’s natural route. Once the stone has been found, it is broken up or turned to dust with a laser. When the scope goes right up inside the kidney, the procedure is known as RIRS (retrograde intrarenal surgery).
It needs an anaesthetic and, in many cases, a ureteric stent (JJ stent) left in place for a while to protect the urinary tract. In return, it can deal with stones that lithotripsy does not treat well, and it makes it possible to confirm during the same procedure that the stone has been cleared.
4. Percutaneous surgery (PCNL)
For large or complex kidney stones, the technique of choice is percutaneous nephrolithotomy: the kidney is reached through a very small puncture in the back and the stone is removed. It works better for bulky stones and is reserved for those cases.
The main thing to remember: no technique is ‘better’ than the others in the abstract. The right one is the one that fits your stone and your circumstances. Part of a urologist’s job is to explain why, in your particular case, one option makes more sense than another.
How to prevent new stones
Having had one stone is the biggest risk factor for having another. So, beyond treating the episode, it is worth finding out why it formed. Some general measures backed by evidence:
- Drink enough water through the day to keep your urine pale. It is the simplest measure and one of the most effective.
- Cut down on salt, which increases the amount of calcium lost in the urine.
- Adjust your diet to the type of stone: they are not all prevented in the same way, which is why knowing the composition is key.
- Do not cut calcium from your diet out of fear: in most cases, reducing it drastically is counterproductive.
- A metabolic assessment for people who keep forming stones: finding the cause means prevention can be aimed at their particular case rather than being generic.
In short
Kidney stones are common and most are highly treatable with minimally invasive techniques. Three things matter: recognising the warning signs that mean you must go to A&E, choosing the treatment according to the size, position and hardness of the stone, and finding the cause so that you can prevent further stones.
If you have kidney stones or have had an episode of renal colic and would like your case assessed, book an appointment. I see patients in Palma (Quirónsalud Palmaplanas) and Manacor (Més Consultes Mèdiques), in English or Spanish.
Appointments: +34 971 918 000 (Palma) · +34 971 559 000 (Manacor). You can call in English.
This article is general information and does not replace a medical consultation. Each case needs to be assessed individually.
