Waxy casts in the urinary sediment of patients with different types of glomerular diseases: results of a prospective study

Abstract

Background: Casts are well known components of the urinary sediment. For most casts, the clinical associations are known and demonstrated, while for waxy casts they are totally unknown.

Methods: Prospective study for the search and count of waxy casts in the urinary sediment of patients with different types of glomerular diseases.

Results: Waxy casts were found in 39 out of 287 patients (13.6%), mostly in low number (1 to 9 out of 100 casts evaluated/sample). They were frequent in postinfectious glomerulonephritis and renal amyloidosis (5/9 patients, 44.5%, p=0.02 for each condition), while they were rare in membranous nephropathy (4/67 patients, 6.0%, 0.04) and absent in focal segmental glomerulosclerosis (0/23 patients, p=0.05). Waxy casts were associated significantly with higher serum creatinine levels (p<0.0001), with the presence of >1 leukocyte/HPF, granular casts and leukocytic casts (p=0.001 to 0.008) and with higher numbers of erythrocytes, leukocytes, renal tubular epithelial cells, granular casts, epithelial casts, and leukocytic casts (p<0.0001 to=0.03).

Conclusions: Waxy casts are uncommon and few in patients with glomerular diseases and are associated with impaired renal function and with several other structures of the urinary sediment.

Keywords: Glomerulonephritis; Urinalysis; Urinary casts; Urinary sediment; Waxy casts.