A kidney stone is a hard piece of material that forms in the kidney from substances dissolved in urine. It can be the size of a grain of sand or a pearl. Looking for photos of stones and their descriptions is normal — there is nothing to be ashamed of.
What kidney stones are and how they form
Urolithiasis, also known as nephrolithiasis, refers to calculi in the organs of the urinary system. These can be sand, small grains, and stones reaching a considerable size. They form due to the accumulation of chemicals present in urine.
Three things contribute to stone formation: sharply acidic urine (pH below 5.5), low diuresis due to lack of fluid, and elevated uric acid in the blood. The most aggressive factor is high acidity: in such an environment, uric acid crystallizes.
The risk is higher with lack of water, metabolic syndrome, use of aspirin, antacids, diuretics, and antibiotics, a high-protein diet low in fiber, physical inactivity, urinary tract infections, and a family history. Stones are associated with hyperparathyroidism, gout, and diabetes mellitus.
People are affected at any age, more often from 20 to 50 years. This accounts for 30–40% of hospitalizations in urology departments, and the lifetime risk is up to 10%.
When to see a doctor
Small stones cause no symptoms and pass in the urine unnoticed. Large stones hurt. The pain starts in the side of the abdomen or lower back, radiates to the groin, testicles, or the area around the vaginal opening, and comes in attacks.
Other signs: high temperature, fever or chills, nausea, vomiting, frequent urination, cloudy urine, blood in the urine, foul-smelling urine, burning during urination.
Renal colic by itself is not a reason to call an ambulance; 103 or 112 — if the pain in the side or back is unbearable and does not go away, or if a high temperature with fever or chills develops.
The diagnosis is made based on symptoms, with questions about illnesses, medications, diet, and family history. Urine and blood tests are needed. For severe pain, the patient is referred to a hospital: adults for computed tomography, pregnant women and children under 16 for ultrasound.
Types of kidney stones: oxalate, urate, phosphate
Stones are classified by composition, size, and shape. By shape, staghorn and simple stones are distinguished. The composition of a stone is clarified by examining the stone itself, so the doctor may ask you to keep a passed calculus.
- Oxalate — made of calcium oxalate, a salt of oxalic acid. In mineralogy these are whewellite and weddellite.
- Urate — made of uric acid salts. Their formation is usually triggered by a metabolic disorder, such as gout.
- Phosphate — calcium phosphate (apatite, brushite) and magnesium ammonium phosphate, or struvite, which grows in urinary tract infections.
- Cystine — a consequence of a genetically determined impairment of cystine reabsorption in the kidney tubules. Rare, like the anomaly itself.
What stones look like: photos, ultrasound, and CT
Externally, it is a dense formation, from a grain of sand to a pearl. The appearance and composition of the stone are determined by the doctor through examination and analysis of the stone itself.
On plain urography, radiopaque and radiolucent stones are distinguished. Ultrasound is the most common method: it shows dilation of the calyceal-pelvic system and ureter, the presence of stones, and the condition of the other kidney. If the pain is severe, adults undergo CT, but the image is read by a doctor, not by a table from the internet.
Stone sizes: what 4 mm means and the largest stones
There are three groups: up to 5 mm, from 5 mm to 2 cm, and more than 2 cm. A 4 mm stone belongs to the first, smallest group: most stones pass on their own, sometimes taking weeks.
Large stones are compared to a pearl. Size is one of the factors by which a urologist chooses the approach.
This material is for reference and does not replace a doctor's consultation: the image and the specific stone should be reviewed by a urologist.
Sources
Update history
Reader reviews
No reviews yet — tell us whether this article was helpful.
Leave a review
This content is for reference and does not replace a doctor's consultation. Medical disclaimer