Hematuria and Dysuria

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Chapter 16 Hematuria and Dysuria

Sandra H. Schwab, MD, Elizabeth R. Alpern, MD, MSCE

1 What is the definition of gross and microscopic hematuria?

Gross hematuria is defined as reddish or pinkish discoloration of the urine with confirmation of red blood cells (RBCs) by microscopy. If the RBCs come from glomeruli, the acidic nature of the urine may change hemoglobin to hematin, causing the urine to appear brownish, tea-colored, or cola-colored.

Microscopic hematuria is normal-appearing urine that, when centrifuged, has ≥5 RBCs per high-power field on microscopy.

2 What else, besides RBCs, can cause urine to appear red or brown?

Reddish or brownish discoloration of the urine from some compound other than blood is common. Myoglobinuria and porphyrinuria present with red or tea-colored urine. Several ingestions also discolor the urine. Infants may have precipitation of urate crystals that make their urine appear red or orange in the diaper.

3 What can cause a “false-positive” urine dipstick?

You may encounter a positive urine dipstick, but upon microscopic examination no RBCs are seen. The dipstick is sensitive to any heme compound and will be positive for intact red blood cells as well as hemoglobin from hemolyzed RBCs and myoglobin from rhabdomyolysis. Several other oxidizing compounds, such as bleach or microbial peroxidase, can also turn the dipstick spuriously positive.

Goldsmith DI, Novello AC: Clinical and laboratory evaluation of renal function. In Edelmann CM (ed): Pediatric Kidney Disease, 2nd ed. Boston, Little, Brown and Company, 1992, pp 461–465.

Liao JC, Churchill BM: Pediatric urine testing. Pediatr Clin North Am 48:1425–1436, 2001.

Liebelt EA: Hematuria. In Fleisher GR, Ludwig S, Henretig FM (eds): Textbook of Pediatric Emergency Medicine, 5th ed. Philadelphia, Lippincott Williams & Wilkins, 2006, pp 345–349.

4 What is the most likely diagnosis of a child presenting to the emergency department (ED) with “red urine”?

The majority of children who visit an ED for red urine are diagnosed with urinary tract infections (UTIs) (26% with documented infections and 23% with suspected UTI or viral cystitis). Perineal irritation accounts for 11% of cases, and meatal stenosis with ulcer is found in another 7%. Hematuria is from traumatic injuries in 7% of cases; acute glomerulonephritis is diagnosed in 4%, and a rare patient may have a Wilms’ tumor or other oncologic process involving the genitourinary tract.

Even though parents or patients may assume that blood in the diaper or toilet is from urine, it may actually be from several other sources: vaginal bleeding (menses, foreign body, infection, trauma), rectal bleeding (fissure, hemorrhoid, trauma), or urethral prolapse.

Ingelfinger JR, Davis AE, Grupe WE: Frequency and etiology of gross hematuria in a general pediatric setting. Pediatrics 59:557–561, 1977.

5 Is there a way to determine glomerular versus nonglomerular blood in the urine?

See Table 16-1.

Table 16-1 Glomerular Versus Nonglomerular Blood in the Urine

Glomerular	Nonglomerular
Brown or tea-colored urine	Bright red or pink urine
RBC casts	Blood clots
Dysmorphic RBCs	Normal RBC morphology
Cellular casts	Blood at initiation or termination of urination
Proteinuria

RBC = red blood cell.

Adapted from Kalia A, Travis LB: Hematuria, leukocyturia, and cylindruria. In Edelmann CM (ed): Pediatric Kidney Disease, 2nd ed. Boston, Little, Brown and Company, 1992, pp 553–563.

6 What is the differential diagnosis of hematuria in a child?

See Table 16-2.

Table 16-2 Differential Diagnosis of Hematuria in Children

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Glomerular	Nonglomerular
Postinfectious nephritis (poststreptococcal glomerulonephritis)	Urinary tract infection
	Hemorrhagic cystitis
IgA nephropathy	Urethritis
Hereditary nephritis (Alport syndrome)	Sickle cell disease or trait
Benign familial hematuria (thin basement membrane disease)	Meatal stenosis
	Nonsteroidal anti-inflammatory drugs
Exercise-related hematuria	Trauma
Subacute endocarditis	Urolithiasis
Ventriculoperitoneal shunt nephritis	Hypercalciuria
Hemolytic uremic syndrome	Wilms’ tumor
Systemic lupus erythematosus	Polycystic kidney disease
Henoch-Schönlein purpura	Urethral prolapse
	Antibiotics (penicillins, cephalosporins)
	Ureteropelvic junction obstruction

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