[Paraprotein-related kidney disease. Experience in 22 cases]

One of the devastating consequences of monoclonal gammopathies is the development of end-stage kidney disease, which can be prevented with an early diagnosis. Renal involvement can be secondary to saturation of paraproteins with intratubular precipitation or the glomerular deposition of paraproteins with secondary inflammation and destruction. These conditions can also be associated with monoclonal gammopathies that do not meet hematological treatment criteria, called monoclonal gammopathies of renal significance (MGRS).

To report a retrospective analysis of patients who underwent a renal biopsy and whose final diagnosis was a form of monoclonal gammopathy.

We reviewed the clinical and laboratory features and response to treatment of 22 patients aged 63 ± 12 years (55% women) with a pathological diagnosis of a nephropathy associated with paraproteinemia.

The most common hematological diagnosis was amyloidosis in 50% of patients, followed by cast nephropathy. The predominant clinical presentations were proteinuria (without nephrotic syndrome) and nephritic syndrome. Classic criteria such as erythrocyte sedimentation rate > 100 mm/h and protein-albumin gap were unusual. Serum light chain quantification was the test with the best yield to detect paraproteins.

In this group of patients, light chains tend to affect the kidney more commonly than heavy chains. The prognosis of multiple myeloma is much worse than MGRS.