Abstract
Rapidly progressive glomerulonephritis (RPGN) is a condition of the kidney characterized by a rapid loss of renal function with acute or subclinical gross hematuria or proteinuria. On urinary sediment examination, glomerular hematuria due to glomerulonephritis and other conditions often shows various types of cast, including glomerular-type red blood cells (RBCs) and RBC cast. We encountered four cases of RPGN with difficulty in the detection of glomerular-type RBCs on urinary sediment examination. Their common findings include: (1) a mixture of RBCs in a dehemoglobin status, with little variety and difference in size in the overall pattern of appearance; (2) the appearance of various types of cast, including RBC cast, granular cast, and wax cast; (3) a marked decline in renal function, as indicated by a low estimated glomerular filtration rate (eGFR); and (4) strong positivity for protein and occult blood in qualitative urinary examination. In two cases, morphological information on RBCs (RBC-Info.) of UF-1000i (Sysmex) was “Mixed?”. On the basis of these results, it was possible to infer the pathogenesis and suspect glomerular hematuria. With severely impaired renal function, the RBC morphology in the urinary sediment may not show any change despite glomerular hematuria, and care should be taken in determining the RBC morphology. In addition, if glomerular hematuria is suspected on the basis of the pattern of the urine sediment image (RBC morphology, appearance of various types of cast) and other test results, it is important to perform a detailed speculum examination considering the possibility of appearance of a few RBC casts associated with glomerular hematuria.
