Struvite kidney stones (infection stones): causes and treatment

Kidney stones are hard lumps that form in the kidneys, according to the NHS. They come in several types. NHS inform lists calcium stones, struvite stones, uric acid stones and cystine stones. Calcium stones are the most common, and South Tees Hospitals NHS Foundation Trust notes that the majority are calcium oxalate, followed by calcium phosphate.

Struvite stones are different in how they form. South Tees explains that they are produced by urea-splitting bacteria in people with urinary tract infections. Because the infection is the driver, they are sometimes called infection stones. NHS inform describes them as often caused by infections, most commonly after a urinary tract infection that has lasted a long time.

The NHS says small stones are common and may cause no symptoms and pass unnoticed in the urine. Larger stones can cause severe pain that usually starts in the side of the tummy or lower back, may spread to the groin, and may come and go. Other symptoms include a high temperature or feeling hot, cold or shivery, feeling or being sick, needing to pee often and cloudy pee.

With struvite stones the infection component adds to this picture. Recurrent or persistent urine infection symptoms, such as needing to pee often, cloudy urine, or repeated treatment for the same infection, together with loin pain, are a reason to ask for the urinary tract to be checked for a stone.

• Severe pain in the side or lower back that comes in waves.

• High temperature, shivering, sickness.

• Frequent urination, cloudy or unpleasant-smelling urine.

• Repeated urine infections that keep returning after antibiotics.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you think you have kidney stones and you are in severe pain, or have a high temperature or feel hot, cold or shivery. An infected, blocked kidney is an emergency, and a high temperature together with kidney stone pain should not be left to settle at home. If you feel very unwell, are confused, or have a rapid heartbeat or breathing, call 999 or go to A&E.

The NHS says a doctor can usually diagnose kidney stones from symptoms, and may ask about conditions, medicines, diet and family history. Urine and blood tests may be used, and if you have severe pain you may be referred to hospital for a CT scan if you are an adult, or an ultrasound scan if you are pregnant or under 16.

NICE guideline NG118 covers assessment and management of renal and ureteric stones. When a stone is passed or removed, it can be sent for analysis, and South Tees' pathology service describes stone analysis as the test used to identify what the stone is made of. Knowing that a stone is struvite shapes the prevention plan.

The NHS says most kidney stones can be treated at home with medicine, with painkillers, anti-sickness medicines and medicines to help the stone pass, and that larger stones may need a procedure or surgery in hospital to break them up or remove them, for example using shock waves.

For struvite stones in particular, NHS inform says antibiotics may be prescribed to help prevent a urinary tract infection or kidney infection, which are the main causes. Plymouth Hospitals says urine needs to be kept free of infection and may require long-term antibiotics. The exact combination of stone removal and infection treatment is a decision for the urology team looking after you.

General prevention advice from Plymouth Hospitals also applies: increasing fluid intake is almost always possible and reduces the risk of forming stones, and reducing salt intake is usually helpful.

Stones that are treated fully, together with control of urine infection, have a good chance of not coming back, but recurrence is common across stone types: Plymouth Hospitals says half of people with a stone go on to form further stones over the next 10 years. Follow-up with urology and prompt treatment of any new urinary infection are the main protections.

On the NHS, a GP or emergency department arranges urgent imaging and urology referral, and procedures to remove stones are provided by urology services. Private urology is available for imaging and procedures, but ongoing infection surveillance and antibiotic planning benefit from continuity with one team.