Kidney stones

A kidney stone is a hard mineral lump, sometimes tiny and sometimes pearl-sized, that develops in either or both kidneys when urine carries excess minerals. Small stones are common and often cause no symptoms, but larger ones can lodge in the urinary tract and block urine flow. Poor hydration, metabolic syndrome, certain medicines, a high-protein, low-fibre diet, inactivity, recurrent urinary infections and a family history all make stones more likely. Severe pain in the back or side, sometimes spreading to the groin, often comes with blood in the urine, nausea, vomiting, fever and chills. Clinicians usually diagnose stones from history and examination, supported by urine tests, blood tests and imaging such as CT or ultrasound. Most stones pass naturally with plentiful fluids and medicines for pain and nausea; shock waves, a scope or surgery remove larger ones.

Seek urgent care for fever with flank pain, inability to pass urine, or blood in the urine. See a doctor for burning on urination that lasts more than two days, urinary symptoms that keep returning, or any change in urinary flow in men over 50. Call the local emergency number for any symptom that is sudden and severe. This page is a reference for healthcare professionals and does not replace an assessment.