A large number of benign and serious conditions can cause hematuria (blood in the urine) in children. Gross hematuria is most frequently observed with urinary tract infection (UTI), irritation of the meatus or perineum, trauma, nephrolithiasis (including hypercalciuria without stones), sickle cell disease/trait, post-infectious glomerulonephritis, and IgA nephropathy (the last two are types of kidney diseases).
The most common causes of persistent microscopic hematuria in children include glomerulopathies, such as IgA nephropathy and glomerular basement membrane diseases (mainly Alport syndrome or thin basement membrane disease - again, more kidney diseases), hypercalciuria and microlithiasis, and UTI.
Obtaining kidney blood tests and imaging studies (i.e. ultrasound) are reasonable steps. I would also consdider a referral to a urologist or kidney specialist.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Thanks,
Kevin, M.D.