Usually blood cells are not found in urine. Their occurence is an important symptom of many renal and urogenital diseases.
The naked eye may be deceived by red dyes. Most dipsticks cannot reliable distinguish between free haemoglobin (hemoglobinuria) and red blood cells (hematuria).
Haematuria is the leading urinary symptom of the nephritic syndrome, which also includes granular or red cell casts and hypertension. It differs from nephrotic syndrome in a lower degree of proteinuria and peripheral oedema. Nephritic syndrome is the clinical presentation of glomerular damage and therefore haematuria is characterized by dysmorphic erythrocytes. Other grounds of haematuria show normal erythrocytes and cause different accompanying symptoms.
The diagnosis of haematuria is mad by dipstick or microscopy of fresh urine.
Haematuria may be caused by bleeding throughout the urogenital tract. That's why a variety of hereditary kidney diseases cause haematuria, such as glomerular, interstitial, and cystic diseases as well as malformations and tumours.
The degree of haematuria defines its visibility by a naked eye. Accordingly we call it macroscopic or microscopic.
By the portion of dysmorphic erythrocytes, we get an idea for where the bleeding occurs. In glomerular haematuria, a glomerular damage allows erythrocytes to pass across the basement membrane into the urine, which results in numerous dysmorphic erythrocytes. Other bleeding sites generate normal erythrocytes.
We further distinguish benign and malign haematuria according to the prognosis of the underlying renal disease.
Hematuria is an early sign of Alport syndrome occuring in early childhood. In heterozygous carriers it remains the only abnormality.
Microscopic hematuria is an early symptom. It can become macroscopic after respiratory infections.
Hematuria is microscopic and glomerular.