How stones form & The pain of a passing stone
Lesson 1 · 5 min
Based on MedlinePlus en español — Kidney Stones. Original educational summary, read by a medical doctor and confirmed reliable, pending formal approval. Not medical advice.
Learning objectives
- Explain how stones form.
- Explain the pain of a passing stone.
How stones form
Kidney stones are hard deposits of minerals and salts that form inside the kidneys. Urine normally contains substances that prevent crystals from forming, but when urine becomes concentrated, minerals such as calcium, oxalate, and uric acid can crystallize and stick together. Stones range from grains of sand to the size of a pebble. Small stones may pass unnoticed, while larger ones can block the flow of urine. Not drinking enough fluid is one of the most important risk factors.
The pain of a passing stone
A stone that stays in the kidney may cause no symptoms. Symptoms begin when it moves into the ureter, the narrow tube between kidney and bladder. The hallmark is severe pain in the side and back, below the ribs, which may radiate to the lower abdomen and groin and come in waves. Other signs include pink, red, or brown urine, painful or frequent urination, nausea, vomiting, and fever if infection is present.
Key concepts
- How stones form
- Kidney stones are hard deposits of minerals and salts that form inside the kidneys.
- The pain of a passing stone
- A stone that stays in the kidney may cause no symptoms.
- Diagnosis and treatment
- Doctors diagnose stones with urine tests, blood tests, and imaging such as CT scans or ultrasound.
- Preventing new stones
- A person who has had one stone has a higher chance of another, so prevention matters.