Salt and kidney stones: what to know

The kidneys filter waste into urine. A high-salt diet can change the balance of minerals in urine, including increasing calcium loss for some people. When urine becomes concentrated, crystals may join together and form a stone. Stone type, family history, medicines, diet, and dehydration all influence risk, so salt is only one part of the picture.

A stone may cause severe pain in the flank or abdomen, pain when passing urine, nausea, or difficulty passing urine. These symptoms can have other causes; their presence does not by itself confirm a stone.

Drink fluids regularly unless a clinician has given you a fluid restriction, and reduce heavily salted packaged foods, preserved foods, and salty sauces. Do not make extreme diet changes or remove calcium-containing foods without advice. If you have had a stone, a GP consultation can help review its type, medicines, fluid habits, and whether testing is appropriate. An abdominal ultrasound may be used when imaging is needed.

Seek urgent care for severe or persistent pain, fever or chills with urinary symptoms, repeated vomiting, blood in the urine, or difficulty passing urine. A blocked urinary passage with infection can become serious. Prompt assessment is also sensible if you have one functioning kidney, known kidney disease, or cannot maintain fluids.

Ask which stone type is suspected, how much fluid is suitable for you, whether your medicines affect stone risk, and whether urine or stone analysis would guide prevention. Report flank pain, painful urination, or reduced urine clearly.