Recurrent Hematuria

Introduction

Recurrent gross hematuria is a characteristic presentation of specific glomerular and non-glomerular disorders in children, standing in contrast to conditions like acute postinfectious glomerulonephritis which typically manifest as a single acute episode.
The latency period between an infection and the onset of hematuria is diagnostically useful; gross hematuria occurs within 1 to 2 days of an upper respiratory infection in IgA nephropathy, whereas it takes 1 to 2 weeks in acute postinfectious glomerulonephritis.

IgA Nephropathy (Berger Disease): This is the most common chronic glomerular disease in children and is characterized by a predominance of IgA within the mesangial deposits.
Patients typically present with recurrent episodes of macroscopic hematuria that coincide with upper respiratory tract or gastrointestinal infections (synpharyngitic presentation).
Alport Syndrome (Hereditary Nephritis): A progressive hematuric glomerulopathy associated with profound ultrastructural changes of the glomerular basement membrane (GBM), classically described as having a "basket weave" appearance.
It is caused by pathogenic mutations in the COL4A genes (encoding the alpha chains of type IV collagen) and is frequently associated with high-frequency sensorineural deafness and ocular defects like lenticonus.
Thin Basement Membrane Disease (TBMD): Often referred to as benign familial hematuria, this condition is caused by heterozygous mutations in the COL4A3 and COL4A4 genes.
Patients typically exhibit asymptomatic microscopic hematuria with normal renal function, although rare cases may progress to significant proteinuria or renal insufficiency.

Idiopathic Hypercalciuria: A common metabolic cause of recurrent gross or microscopic hematuria, which can present alongside dysuria and abdominal pain, in the absence of hypercalcemia.
Urolithiasis: Kidney stones can cause recurrent hematuria, usually accompanied by severe flank pain (renal colic) that radiates anteriorly, originating from urinary tract obstruction.
Nutcracker Syndrome: Unilateral bleeding caused by the compression of the left renal vein between the aorta and superior mesenteric artery, presenting with recurrent gross or persistent microscopic hematuria, left flank pain, and occasionally left varicocele.

A meticulous clinical history must ascertain the timing of hematuria in relation to infections, the color of the urine (cola-colored vs. bright red), and any associated symptoms like flank pain or dysuria.
A detailed family history is critical given the hereditary nature of Alport syndrome, TBMD, and polycystic kidney diseases.
Urinalysis and phase-contrast microscopy are utilized to differentiate glomerular bleeding (characterized by dysmorphic red blood cells and RBC casts) from non-glomerular bleeding (characterized by isomorphic RBCs).

Investigation	Clinical Utility and Findings
Urine Microscopy	The presence of >30% dysmorphic RBCs (acanthocytes) or RBC casts strongly indicates glomerular disease; >90% isomorphic RBCs suggest lower tract causes.
Serum Complement (C3/C4)	Normal levels in IgA nephropathy help differentiate it from postinfectious glomerulonephritis, where the C3 level is significantly reduced.
Urine Calcium-to-Creatinine Ratio	A spot ratio >0.2 mg/mg in a child over 2 years of age suggests hypercalciuria as the underlying cause of recurrent hematuria.
Audiometry & Ophthalmologic Exam	Used to screen for high-frequency sensorineural hearing loss and ocular abnormalities characteristic of Alport syndrome.
Renal Ultrasonography	Essential to rule out structural anomalies, urolithiasis, cystic kidney diseases, or tumors.
Renal Biopsy	Indicated for recurrent gross hematuria if it is associated with decreased renal function, hypertension, or significant proteinuria, in order to confirm IgA nephropathy or other progressive forms of glomerulonephritis.
Genetic Testing	Mutation analysis of the COL4A genes confirms familial hematuria syndromes, distinguishing between Alport syndrome and TBMD.

Patients with minimal symptoms require long-term follow-up because progressive renal dysfunction can develop decades later in adulthood.
First-line therapy for patients with significant proteinuria involves renin-angiotensin system (RAS) blockade using angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) to lower proteinuria and slow disease progression.
If proteinuria persists despite maximal RAS blockade, immunosuppressive therapy with corticosteroids is recommended, particularly for patients with a preserved glomerular filtration rate.

Patients with TBMD generally require only routine monitoring for the development of proteinuria, hypertension, or renal dysfunction, as the condition follows a mostly benign course.
Therapy for Alport syndrome is supportive and focuses on utilizing ACE inhibitors to manage proteinuria and control hypertension, though patients often eventually progress to end-stage kidney disease requiring transplantation.

Idiopathic hypercalciuria is managed with a high fluid intake, along with a diet restricted in sodium and animal protein.
If dietary modifications fail, oral thiazide diuretics (e.g., hydrochlorothiazide) are used to stimulate renal calcium reabsorption, effectively preventing recurrent hematuria and stone formation.
Nutcracker syndrome in children often resolves spontaneously over 24 months, as normal weight gain and retroperitoneal adipose tissue deposition reduce the compression of the left renal vein.