Comparison of Turkish Primary, Recurrent, and Non Stone-Forming Patients Using Hounsfield Unit Measurements: How Useful Is It?

Introduction: To investigate renal papillae attenuation value differences between controls and stone-forming (SF) patients and to evaluate the impact of mean Hounsfield unit (HU) measurements on the predictivity of stone development.

Materials And Methods: We compared papillae attenuation values in SF groups and a healthy stone-free control group. Metabolic evaluations were carried out on 88 primary and 98 recurrent SF patients, and 94 age-matched control patients were included. The papillae tip attenuation was measured using non-enhanced computed tomography scans in HU for an area with a mean size of 0.2 cm. Inclusion criteria to the study were known stone composition (CaOx), unilaterality, and radiological examinations done in our center.

Results: In this study, 186 patients who met the criteria and 94 age-matched control patients were divided into 3 groups: the primary SF (Group 1), the recurrent SF group (Group 2), and the control group (Group 3). Metabolic variables which were compared between primary and recurrent SF did not show any significant difference, except urinary volume and phosphorus. The median (interquartile range) value of papillae HU density for the control group was 26.23 (3.84), for primary SF group it was 26.50 (11.25), and for recurrent SF group it was 29 (13). A significant difference in papilla HU levels for each group was found (p = 0.008).

Conclusion: This study implied that HU values reflect the severity of the stone disease, although they could not discriminate controls from primary stone formers whose stone forming risk is lower compared to recurrent stone formers.