Table 1.

Differential diagnosis of kidney diseases based on kidney size, echogenicity, and symptoms

Differential Diagnosis of Kidney Diseases
Normal echogenicity with normal or increased  kidney sizeNormal or increased echogenicity with increased  kidney size and reduced kidney function
 Early diabetic nephropathy
Normal echogenicity with increased kidney size  and normal kidney function Vasculitis
 Tubulointerstitial disease (e.g., acute interstitial nephritis)
 Steroid use
 Obesity Amyloid
 Tall stature Multiple myeloma
 Acromegaly HIV nephropathy
 Diabetes Pre-eclampsia
Asymptomatic, unilateral increase in kidney sizeIncreased medullary echogenicity with normal cortex
 Hypertrophy from decreased function of other kidney Medullary nephrocalcinosis
 Renal duplication anomaly Tamm Horsfall protein in tubules
 Lymphoma/leukemia (usually affects both kidneys) Urate nephropathy
 Sickle cell disease
Symptomatic, unilateral increase in kidney size Sjögren syndrome
 Medullary sponge kidney
 Acute vascular insult (e.g., renal vein thrombosis)Decreased cortical echogenicity (i.e., dark cortex)
 Urinary tract obstruction
 Acute cortical necrosis
  • Kidney diseases may have a particular appearance based on kidney length, echogenicity, and symptoms as listed in the table above. Although baseline kidney size is often not known, if a change in kidney size >1 cm is detected relative to a prior study, it is unlikely to be due to interobserver variability (6).