UROLITHIASIS (URINARY SYSTEM STONES)
As clinicians, we are interested in the diagnosis and effective treatment of stone disease. However, metabolic research that will provide medical treatment and lifestyle changes to reduce the recurrence of stone formation (evaluation) is at least as important as stone treatment. Without such follow-up and medical treatment, the 5-year stone recurrence rate is around 50%.
There is a liquid part in the urine and some crystal and organic substances dissolved in this liquid. Normally this crystal etc. If the ratio of substances in the urine increases (they become supersaturated), they lose their solubility and lead to stone formation.
Supersaturation depends on urine pH, ionic strength, solute concentration and complexing properties. The solubility of substances in urine can vary dramatically in different physiological situations. While the first urine in the morning is relatively acidic, there is alkaline urine after meals.
STONE FORMATION MECHANISMS
- FREE PARTICLE THEORY:
Not very supported. The crystal mass settles and grows in the distal tube and collector tubes.
- FIXED PARTICLE THEORY:
Crystals settle inside or on the walls of the tube cells. It adheres and grows there until a stone is formed.
- THEORY OF AGENTS THAT MODIFY CRYSTAL FORMATION:
- INHIBITORS:
It is the name given to substances that prevent the formation of stones in the urine.
Mg, citrate, pyrophosphate, acidic glycoprotein (nephrocalcin), alanine, Glucose amino glycan (GAG). )
COMPLEXORS :
By binding with calcium (Ca), it becomes more soluble (melts) They form components and prevent stone formation.
Phosphate, Citrate, Sulphate, Mg (Mg and citrate are both inhibitors and complexors)
PROMOTERS Agents that predispose to stone formation:
THM (Tamm – Horsfall Protein = Uromucoid = Matrix + 3% Sialic acid), GAG (glucose amino glycan), Matrix (a kind of protein).
HOMOGENEOUS NUCLEATION :
It is the formation of pure stones as a result of supersaturation of only one type of crystals found in urine.
HETEROGENEOUS NUCLEATION:
It occurs as a result of the precipitation of other types of crystals on tissue, matrix, protein or other crystals. are stones. The supersaturation concentration required for heterogeneous nucleation is less than that required for homogeneous nucleation. (example: Calcium phosphate (CaPO4) and Uric acid stones can form heterogeneous nucleation focus for Ca Oxalate stones.)
NUCLEATION THEORY:
Nucleation theory suggests that urinary stones are formed from foreign bodies and crystals in supersaturated urine. However, stones do not always form in patients who urinate excessively or are dehydrated. In addition, the 24-hour urine of those who form stones is completely normal in terms of stone-forming ion concentrations.
CRYSTAL INHIBITION THEORY:
Magnesium (Mg), citrate. It suggests that stones are formed due to the absence or low density of stone formation inhibitors such as , pyrophosphate, acidic glycoprotein (nephrocalcin), alanine, Glucose amino glycan (GAG). The theory does not have absolute validity, since most people who lack these inhibitors never form stones, and paradoxically, stones can form in people who have plenty of these inhibitors.
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