The usefulness of densitometry in predicting the composition and fragility of urolithiasis.
BACKGROUND
The choice of ideal treatment for a given lithiasis is a crucial factor for its success, minimizing the number of interventions and complications. Previous determination of stone composition and its fragility is desirable, to predict its behavior during extracorporeal shock wave lithotripsy and for evaluation of its appropriateness, or to set the indication for other techniques.


OBJECTIVE
To determine the role of densitometry in the prediction of composition and fragility of urinary lithiasis undergoing SWL.


METHODS
Experimental prospective, blinded, in vitro study using 193 urinary calculi of known composition : monohydrated calcium oxalate, mixed calcium oxalate, uric acid, and calcium carbonate, obtained from spontaneous passage or surgery. Densitometry and SWL were performed on them. We compare the mineral composition of the stone and mineral density of each composition group to check if they are characteristic of each type and correlate these parameters with the energy dose required to fragment them down to a given fragment size.


RESULTS
Only 53 out of 193 stones showed valuable data. Calcium carbonate was the composition showing grater mineral content and density (1,24 gr and 0,47 gr/cm2), followed by mixed oxalate (0,51/0,26) and uric acid (0,52/ 0,15), finishing with the monohydrate calcium oxalate group (0,32/0,05).Only the comparison between calcium carbonate and monohydrated calcium oxalate showed statistically significant results (p<0,05). Correlation coefficients between mineral content (0,347) and density (0,424) and the energy used for stone fragmentation to a given fragment size were statistically significant (p<0,05) CONCLUSIONS: In our study, the use of densitometry to determine stone composition and lithiasic fragility did not show conclusive results due to the limited number of calculi tested. Nevertheless, there are signs that, with a different study design , more practically useful results could be achieved.
Unidad de Urologia y Nefrologia.Hospital Universitario Virgen del Rocio. Sevilla.Spain.
Enrique
E
Argüelles-Salido
Unidad de Urologia y Nefrologia.Hospital Universitario Virgen del Rocio. Sevilla.Spain.
Jose Maria
JM
Lozano-Blasco
Servicio de Urologia. Hospital Universitario Virgen del Rocio. Sevilla.Spain.
Jorge
J
Subira-Rios
Unidad de Urologia. Hospital Universitario Virgen del Rocio. Sevilla.Spain.
Pastora
P
Bernardo-Villar
Unidad de Analisis Clinicos.Hospital Universitario Virgen del Rocio. Sevilla.Spain.
Virtudes
V
Podio-Lora
Unidad de Urologia y Nefrologia.Hospital Universitario Virgen del Rocio. Sevilla.Spain.
Pedro
P
Campoy-Martínez
Unidad de Diagnostico por Imagen. Hospital Universitario Virgen del Rocio. Sevilla.Spain.
Ricardo
R
Vazquez-Albertino
Unidad de Urologia y Nefrologia.Hospital Universitario Virgen del Rocio. Sevilla.Spain.
Rafael
R
Medina-Lopez
D002119:Calcium Carbonate / Q000032:analysis; D002129:Calcium Oxalate / Q000032:analysis; D002623:Chemistry Techniques, Analytical; D003720:Densitometry; D006244:Hardness; D006245:Hardness Tests / Q000379:methods*; D006801:Humans; D066298:In Vitro Techniques; D008096:Lithotripsy; D011446:Prospective Studies; D016037:Single-Blind Method; D014527:Uric Acid / Q000032:analysis; D014545:Urinary Calculi / Q000737:chemistry*; D052878:Urolithiasis / Q000378:metabolism / Q000628:therapy
D002129:Calcium Oxalate; D014527:Uric Acid; D002119:Calcium Carbonate