Kidney stones, also called urolithiasis or nephrolithiasis, are diseases caused by stones or stones inside the kidneys or urinary tract (ureters or bladder). A stone or calculation can be as small as a grain of sand or as large as a pearl. Most kidney stones are eliminated naturally.  During its expulsion it can stay in the urinary tract, blocking the flow of urine and causing great pain and complications. Sometimes a stone is not easy to remove from the body, and medical-surgical treatment is needed.

Urinary lithiasis is the presence of calculi or stones in the kidney and the urinary tract (ureters or bladder). Under certain circumstances, these substances precipitate and form calculi or stones. They start when high concentrations of importance should be eliminated in the urine after passing through the kidneys and urinary tract.

Treatment of kidney stones

 Non-pharmacological treatment

Hydration. An intake of 2.5-3 litres per day consumed continuously is recommended. Usually waters with neutral pH. Carbonated waters that can go well for uric acid stones would not be indicated in calcium ones. Drinks with citrus fruits are also recommended as they provide magnesium and citrate, which are substances that inhibit urine crystallization. A daily diuresis (amount of urine eliminated per day) of two litres is recommended.

Feeding. A balanced diet rich in vegetables and fibre and restricting the consumption of proteins of animal origin is recommended, limiting salt in the diet. An average daily calcium intake (1-1.2 g/day) is recommended.

Lifestyle. It is recommended to avoid a sedentary lifestyle and obesity (BMI: body mass index 18-25 kg/m2), control stress, avoid water imbalances (excessive sweating due to high temperatures or secondary to intense sports or work activity, etc.)

Pharmacotherapy

Pharmacological treatment is indicated in those patients who have high-risk factors or those in whom general measures have failed.

The objective is to correct the alterations in the urine composition and, thus, avoid the formation of stones.

Pharmacological treatment is usually adequate as long as the patient strictly follows the treatment guidelines prescribed by the health professional.

The most commonly used medications are thiazides, potassium citrate, orthophosphate, magnesium and allopurinol.

Thiazides (hydrochlorothiazide) and pseudothiazides (indapamine). They decrease urinary calcium excretion in patients with hypercalciuria. Side effects of this medication include diabetes, gout, erectile dysfunction, and normocalcemic hyperparathyroidism (increased parathyroid protein causing calcium to grow).

Alkali citrate (sodium citrate, potassium citrate).  Citrate inhibits the growth and aggregation of crystals in the urine and forms complexes (links) with calcium and phosphate, decreasing these substances in the urine. It is used to increase urine citrate in patients with low citrate levels. In addition, it increases the pH of urine (alkalinizes). Other alkalizing substances used are sodium and potassium bicarbonate.

Magnesium. It inhibits the growth of calcium phosphate crystals and the formation of bauxite stones.

Allopurinol. Lowers uric acid levels. Sometimes uric acid crystals are the nucleus from which calcium crystals will aggregate to form calcium stones. Tolerability is excellent, and side effects may occur but at high doses.

Pyridoxine (vitamin B6). It is indicated in patients with primary and idiopathic hyperoxaluria (increased oxalate in the urine) and orthophosphate.

Trophos-K (slow release of potassium phosphate). It reduces the concentration of calcium in the urine (hypocalciuria) and maintains bone mass in patients with absorptive hypercalciuria (high levels of calcium in the urine). It is well tolerated.

D-penicillamine. Indicated in cystinuria. It favours that cystine can dissolve in urine and does not form stones. It is very effective, but it has significant side effects such as nephrotic syndrome (excess protein in the urine), dermatitis, and pancytopenia (decrease in red and white blood cells and platelets). Therefore, an analytical follow-up with blood count, urea, electrolytes and vitamin B6 is required. Doses of pyridoxine accompany it to avoid vitamin b6 deficiency.

Alpha-mercaptopropionyl glycine (tiopronine). It is similar to D-penicillamine but with fewer side effects and less effectiveness.