Hematuria is one of the most common urinary findings that bring children to the attention of the pediatric nephrologist. It is defined as the presence of >5 red blood cells (RBCs) per high-power field in three of three consecutive centrifuged specimens obtained <1 week apart. The hematuria may be overtly bloody or microscopic. It may be symptomatic or asymptomatic, transient or persistent, and either isolated or associated with proteinuria and other urinary abnormalities.

The etiology of this hematuria may be the result of a structural disruption in the integrity of the glomerular basement membrane caused by inflammatory or immunologic processes. But other causes, such as chemicals, may cause disruptions of the renal tubules and calculi that may cause mechanical erosion of mucosal surfaces in the genitourinary tract, resulting in hematuria. Collagen vascular disease is a somewhat antiquated term used to describe diseases of the connective tissues that typically include diseases associated with blood vessel abnormalities. Collagen represents 30% of body protein and shapes the structure of tendons, bones, and connective tissues. These collagen vascular disorders are a diverse group of diseases that affect the supporting tissues of the body. Some collagen vascular diseases include: rheumatoid arthritis, systemic lupus erythematosus, scleroderma, dermatomyositis, and polyarteritis nodosa.