tailieunhanh - Chapter 045. Azotemia and Urinary Abnormalities (Part 7)

Isolated microscopic hematuria can be a manifestation of glomerular diseases. The RBCs of glomerular origin are often dysmorphic when examined by phase-contrast microscopy. Irregular shapes of RBCs may also occur due to pH and osmolarity changes produced along the distal nephron. There is, however, significant observer variability in detecting dysmorphic RBCs. The most common etiologies of isolated glomerular hematuria are IgA nephropathy, hereditary nephritis, and thin basement membrane disease. IgA nephropathy and hereditary nephritis can lead to episodic gross hematuria. A family history of renal failure is often present in patients with hereditary nephritis, and patients with thin basement. | Chapter 045. Azotemia and Urinary Abnormalities Part 7 Isolated microscopic hematuria can be a manifestation of glomerular diseases. The RBCs of glomerular origin are often dysmorphic when examined by phase-contrast microscopy. Irregular shapes of RBCs may also occur due to pH and osmolarity changes produced along the distal nephron. There is however significant observer variability in detecting dysmorphic RBCs. The most common etiologies of isolated glomerular hematuria are IgA nephropathy hereditary nephritis and thin basement membrane disease. IgA nephropathy and hereditary nephritis can lead to episodic gross hematuria. A family history of renal failure is often present in patients with hereditary nephritis and patients with thin basement membrane disease often have other family members with microscopic hematuria. A renal biopsy is needed for the definitive diagnosis of these disorders which are discussed in more detail in Chap. 277. Hematuria with dysmorphic RBCs RBC casts and protein excretion 500 mg d is virtually diagnostic of glomerulonephritis. RBC casts form as RBCs that enter the tubule fluid become trapped in a cylindrical mold of gelled Tamm-Horsfall protein. Even in the absence of azotemia these patients should undergo serologic evaluation and renal biopsy as outlined in Fig. 45-2. Isolated pyuria is unusual since inflammatory reactions in the kidney or collecting system are also associated with hematuria. The presence of bacteria suggests infection and white blood cell casts with bacteria are indicative of pyelonephritis. White blood cells and or white blood cell casts may also be seen in tubulointerstitial processes such as interstitial nephritis systemic lupus erythematosus and transplant rejection. In chronic renal diseases degenerated cellular casts called waxy casts can be seen in the urine. Broad casts are thought to arise in the dilated tubules of enlarged nephrons that have undergone compensatory hypertrophy in response to reduced renal mass