Kidney stones: symptoms, treatment and ways to lower your risk

Kidney stones are a common cause of sudden, severe pain. This article explains what they are, how they are found and treated and how to lower the chance of getting them again, using information from the NHS, MedlinePlus and the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

1. Introduction

A kidney stone is a solid, hard mass that forms in one or both kidneys when certain minerals are present at high levels in the urine ^{[1, 3]}. MedlinePlus says stones range from about the size of a grain of sand to about the size of a pearl. Most pass without medical help, but a stone that gets stuck can block the flow of urine and cause severe pain ^[2]. The NIDDK says kidney stones rarely cause permanent damage if they are treated by a health care professional ^[3]. Still, a stone that blocks urine flow can cause great pain, and fever or chills with a suspected stone need urgent attention, so it is important to know which symptoms need quick attention ^{[1, 2]}. This article is general information, and your doctor decides which tests and treatment suit you.

2. Causes and risk factors

The NHS explains that stones form when chemicals build up in the urine and form hard lumps in the kidneys ^[1]. It lists these risk factors for a first stone ^[1]:

• Not drinking enough water
• Medical conditions that raise certain chemicals in the body, such as metabolic syndrome
• Certain medicines, including some antacids, diuretics (water tablets), antibiotics and aspirin

Factors linked with stones coming back include a high-protein, low-fibre diet, being inactive or bed-bound, frequent kidney or urine infections, a close family history of stones and having had stones before ^[1]. The NIDDK says tests may reveal problems that led to the stone forming ^[3].

3. Signs and symptoms

Small stones often cause no symptoms and may pass in the urine unnoticed ^{[1, 3]}. The NHS says larger stones can cause severe pain that usually starts in the side of the abdomen or lower back, may spread to the groin, and can come and go. Other symptoms are fever, chills, nausea or vomiting, needing to pass urine often and cloudy urine ^[1]. The NIDDK lists sharp pain in the back, side, lower abdomen or groin, and blood in the urine ^[3]. MedlinePlus adds foul-smelling urine and burning when passing urine ^[2].

4. Diagnosis and tests

A doctor usually starts with your symptoms, medical history, medicines, diet and family history of stones, and may order urine or blood tests ^{[1, 3]}. For severe pain, hospital tests may include a CT scan in adults, or an ultrasound in pregnant people and children under 16 ^[1]. MedlinePlus says imaging, urine tests and blood tests are used to diagnose stones ^[2].

5. Treatment and management

The NHS says most stones can be managed at home with medicine, though passing a stone can take a few weeks. Advice includes drinking plenty of water, and a doctor may prescribe pain relief, anti-sickness medicine or medicine to help the stone pass. You may be asked to collect a passed stone so it can be examined ^[1].

Larger stones may need hospital treatment ^{[1, 2]}:

• Shock wave therapy (lithotripsy): sound waves from outside the body break the stone into small pieces.
• Ureteroscopy: a thin tube is passed up the urethra, the tube that carries urine out of the body, to reach the stone.
• Surgery: a thin tube may be passed through a small cut in the back, under general anaesthetic.

6. Prevention and self-care

The NHS suggests these steps to lower the risk of stones ^[1]:

• Drink plenty of water. Adults are advised to drink 2.5 to 3 litres a day and children 1 to 2 litres, unless a doctor says otherwise.
• Add fresh lemon juice to water.
• Limit fizzy, caffeinated and alcoholic drinks.
• Get enough calcium in your diet.
• Check your urine colour, since dark urine suggests dehydration.
• Limit salt. Adults should have less than 6g a day, and children under 11 less, depending on age.

The NIDDK says you may be able to prevent future stones by changing how much sodium (a part of salt), animal protein, calcium and oxalate you consume, and that taking medicines may also help ^[3]. Speak to a doctor before making big changes to your diet ^[1].

7. Special groups

Children and pregnant people may need different imaging, such as ultrasound instead of CT ^[1]. Children are advised to drink less water than adults, and children under 11 should have less salt, depending on age ^[1]. People who have had stones before, or have a close relative with stones, are more likely to get them again, so a doctor may look for an underlying cause ^{[1, 3]}.

8. When to see a doctor

The NHS advises urgent medical help for kidney stones that are causing symptoms ^[1]. Ask for an urgent GP appointment or call NHS 111 or your local advice line if you have severe pain, or a fever or chills with a suspected stone ^[1]. MedlinePlus lists severe back or side pain that does not go away, blood in the urine, fever and chills and vomiting as signs a stone needs medical attention ^[2].

In an emergency, call your local emergency number (112 in India, 911 in the United States).

9. Conclusion

Kidney stones form when minerals build up in urine, and many small stones pass without help. Larger or painful stones can be treated in hospital, and drinking enough water and limiting salt can help lower the chance of more. See a doctor promptly if pain, fever or blood in the urine appears.