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Renal lithiasis

Renal lithiasis, also called urolithiasis or nephrolithiasis, is a disease caused by the presence of stones or stones inside the kidneys or urinary tract (ureters or bladder).

Kidney stones are made up of normal substances in the urine, but, for different reasons, they have concentrated and solidified into larger or smaller fragments.

Depending on where a stone forms (the kidney or the bladder) it can be called a kidney stone or bladder stone, respectively.


Kidney stones can form if the urine is saturated with salts that can produce them, or because the urine lacks the natural inhibitors of this process. This may be related to other factors:

  • A decrease in urinary volume.
  • An increase in the urinary excretion of chemicals that prevent the dissolution of salts in urine.


The forms of clinical presentation in kidney stones are variable depending on the size, composition and location of the stones in the urinary system. Some may go unnoticed.

Nephritic colic: Pain in the lumbar area or lower back that radiates towards the anterior abdomen and towards the genitals; It is caused by the blockage of the urine outlet of the kidney and sometimes causes very intense pain.It is an intermittent pain that is associated with nausea, vomiting, sweating and a feeling of abdominal bloating. It does not usually cause a fever.
Hematuria: It is produced by the lesions caused by the stone in its passage through the urinary tract.
Urine infections: Kidney stones can be the cause or consequence of frequent urinary infections or cystitis.

One of the ways to prevent this condition is to correct any excess intake of calcium, phosphate, oxalate and purines.

In addition, several general dietary measures can allow better control of the disease, such as increasing the intake of fluids, preferably water (the first and simplest of the measures to prevent the disease).

It is essential to follow a low calorie diet, with little salt, limiting animal proteins, sugars and alcohol. Nor are foods such as cocoa, coffee, tea, nuts, etc. recommended.


There are different types of kidney stones depending on the composition of the substances that cause them. These are the most common:

  • Kidney stones formed by calcium oxalate: They are the most common. They are made of calcium and an organic acid.
  • Kidney stones made up of calcium phosphate, which is a type of salt that combines calcium and phosphorus.
  • Kidney stones made of uric acid, a compound formed when the body breaks down substances called purines. These are found in some foods and drinks.
  • Kidney stones derived from protein breakdown: Most common in childhood.

Stones that do not cause symptoms can be discovered during a routine microscopic urine test.

In contrast, stones that cause pain are generally diagnosed by symptoms of renal colic, along with pain in the lower back and groin or pain in the genital area, for no apparent reason.

Microscopic analysis of the urine can reveal the presence of blood or pus, as well as small crystals that form the stone.

Other diagnostic tests that are performed are: abdominal radiography, intravenous urography, retrograde urography, abdominal ultrasound and computerized tomography.


95% of stones located in the ureter pass spontaneously in three to four weeks, depending on their size and position.

Any stone not expelled in two months requires a therapeutic action. Based on an assessment of some factors, such as the frequency of colic episodes, impact on the urinary tract, etc., the specialist will determine the most indicated treatment, which may include a conservative attitude with pain management or an interventionist attitude.

Currently, between 90 and 95 percent of stones can be removed by less aggressive procedures, such as extracorporeal shock wave lithotripsy, which consists of breaking the stones into small fragments that can be expelled more easily (with an efficiency of 90 percent).

Endoscopic removal of stones by ureteroscopy (through the urinary ducts themselves, urethra, bladder, etc.) is also common.

Sometimes uric acid stones dissolve gradually making the urine less concentrated (for example, with potassium citrate), but other types of stones cannot be removed with this method.

In special circumstances, larger stones causing an obstruction may require surgical intervention to be removed.

Copyright Dr. José Luis Canto Pérez 2021. All rights reserved.