A contribution to the study of crystalluria: significance in the diagnosis of metabolic and renal diseases

The study of crystalluria is of great importance for the detection of substances of endogenous or exogenous origin that are present inthe urine, to a greater or lesser extent. Urinary sediment crystals can provide valuable answers for the assessment of therapeutic efficacy, as well as congenital and/or acquired pathophysiological conditions. The nature of the observed crystals informs the clinician of the biochemical irregularity of the urine. Crystalluria is of clinical significance only if it has been studied under good test conditions (sample selection, time and storage conditions). Crystalluria interpretations are performed on the basis of the urinary pH determined with statistically significant reliability. When studying crystalluria by light microscopy, it is necessary to provide light polarization or bidirectional illuminationin order to reduce the risk of diagnostic error.