Treating Renal Lithiasis

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

The aim is to correct the changes in the composition of the urine and thereby prevent the formation of stones. 

Pharmacological treatment is usually effective as long as the patient closely follows the treatment guidelines prescribed by their healthcare professionals. 

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

Thiazides (hydrochlorothiazide) and pseudothiazides (indapamine). These reduce the elimination of calcium in urine in patients suffering hypercalciuria. The side effects related to this medication are diabetes, gout, erectile dysfunction and normocalcaemic hyperparathyroidism (increase in parathyroid protein which causes increased calcium).

Alkaline citrate (sodium citrate, potassium citrate). This is used to increase the quantity of citrate in the urine of patients with low citrate levels. Citrate inhibits the growth and aggregation of crystals in the urine and bonds with calcium and phosphate, reducing these substances in the urine. It also increases the pH of the urine (alkaline). Other alkalising substances used include sodium and potassium bicarbonate.

Magnesium. This inhibits the growth of calcium phosphate crystals and the formation of brucite stones.

Allopurinol. Decreases uric acid levels. Sometimes uric acid crystals are the nucleus onto which calcium crystals aggregate, forming calcium stones. Tolerability is good and side effects may occur, but generally only at high doses.

Pyridoxine (vitamin B6). Indicated in patients with primary and idiopathic hyperoxaluria (increased oxalate in urine) together with orthophosphate.

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

D-penicillamine. Indicated in cases of cystinuria. This helps cystine to dissolve in the urine and not form stones. It is very effective, but has important side effects including nephrotic syndrome (excess protein in the urine), dermatitis, and pancytopaenia (decrease in red and white blood cells and platelets). This requires an analytical follow-up involving a blood count, urea, electrolytes and vitamin B6 measurements. It is accompanied by doses of pyridoxine to avoid vitamin B6 deficiency.

Alpha-mercaptopropionyl glycine (thiopronine). This is similar to D-penicillamine; it is less effective although it does have fewer side effects.

Urinary lithiasis does not always have to be treated surgically. An operation is indicated, in general, when the stones produce recurrent renal colic, bleeding in the urine, grow in size and number and/or produce complications such as urinary infection, urinary tract obstruction, fever and sepsis.

There are various techniques for removing urinary stones. Which one is chosen depends on the number, size, location and composition of the stones.

Extracorporeal shock wave lithotripsy (ESWL). Kidney stones up to 2 cm in size can be treated with this technique. It is most effective on stones located in the kidney, soft stones and in non-obese patients. The complications of this procedure involve the accumulation of stone fragments that obstruct the ureter when they are eliminated (forming a Steinstrasse or “stone street”), haematuria (urine in the blood) which is usually mild, infection, and renal haematoma (severe complication).

Ureterorenoscopy (URS). This is a surgical technique that consists of a retrograde access from the urethra to the ureter and the kidney in order to locate the stone and destroy it using laser energy. The instruments used may be semi-rigid (to treat stones in the ureter) or flexible (to treat kidney stones). Possible complications that may arise are ureteral injury, narrowing of the ureter, a lithiasis fragment may remain in the ureter, infection, haematuria (urine in the blood), fever, and so on.

Percutaneous nephrolithotomy (PCN). This is a surgical technique that consists of a percutaneous puncture in the lumbar area, below the twelfth rib, to access the interior of the renal cavity, break up the stone and remove it. This technique is prescribed for kidney stones of 2 cm or more in size. Possible complications are renal bleeding that requires embolisation (to stop this, a substance is introduced endovascularly at the point of bleeding), renal haematoma, infection, residual fragments, urinoma: collection of urine outside the urinary tract by extravasation, injury to neighbouring organs, etc.

Open and laparoscopic surgery. An operation is usually carried out when the above-mentioned techniques have failed. It accounts for 5% or less of treatments.