Calcium oxalate and other crystals associated with kidney diseases and arthritis

The recognition of tissue deposits of crystalline material in a variety of organs, including the kidney, predated the association of crystals and arthritic disease. Because of this, the pathophysiology of crystal formation and its resultant inflammation is based in part on studies of renal stones. A number of disease states involving renal and articular crystallization exist. The most common of these, uric acid precipitation, or gout, and calcium phosphate precipitation were not reviewed in this discussion. This review described a variety of less common disease states involving articular and renal crystal deposition. The renal diseases discussed included both parenchymal or ectopic crystal deposition, as seen in nephrocalcinosis or cystinosis, and ductal crystallization as seen in renal calculus disease. The crystals involved included not only calcium oxalate, but also aluminum, amino acids and proteins (cystine, hemoglobin, cryoglobulins, and immunoglobulins), purine metabolites (xanthine, hypoxanthine), and even lipids and their degradative enzymes (cholesterol, phospholipids, phospholipase, and fatty acids). The simultaneous occurrence of crystals in both kidneys and joints was found in some cases to result from the systemic deposition of an excess of a particular biological compound. However, of more interest, some renal deposits were shown to more selectively reflect the normal or abnormal function of the kidney in its secretory and excretory roles. This is particularly evident in the variety of arthritic states described in end-stage renal disease.