Pediatric Urology Clinics: Red Urine in a 12-Year-Old Boy

PATIENT PROFILE:

A 12-year-old boy is assessed on the same day that he passed red-colored urine. The boy had been vigorously wrestling with his older brother in the morning; he passed the abnormal-colored urine after lunch. His mother was worried that his kidneys might have been injured during the wrestling.

The boy was delivered vaginally at term after an uncomplicated pregnancy. He was routinely circumcised as a neonate. He was growing and developing normally. Apart from routine childhood illnesses, his past history was unremarkable.

Specific questioning revealed that the urine was passed without discomfort and was dark brownish red. The boy offered that the urine looked like "Coca-Cola." There was no history of frequency, urgency, or incontinence. He voided one further time before the clinic visit; the color of the urine on that occasion was normal. Several weeks earlier, he had experienced a few days of cold symptoms.

Physical examination revealed a healthy-appearing adolescent in no distress. His blood pressure while seated was 100/70 mm Hg in the right arm. There was no edema. Heart sounds were normal and the chest was clear to auscultation. Kidneys and bladder were normal to palpation. There was no bruising about the boy's flanks or suprapubic area. The urethral meatus looked elliptical, of normal caliber, and was not inflamed. Results of the physical examination were otherwise normal.

The boy was able to void during the clinic visit. The urine looked clear. The dipstick revealed a urine pH of 6 and was negative for blood. Results of a microscopic urinalysis were normal. There were no red blood cells, white blood cells, or bacteria. An occasional calcium oxalate crystal and renal tubular epithelial cell were present.

The passage of painless Coca-Cola-colored urine suggests macroscopic hematuria and a source of the bleeding originating at the level of the kidneys. Coca-Cola-colored, tea-colored, brownish, greenish, or blackish urine suggests that hemolysis has occurred, which implies an upper urinary tract origin of the bleeding. Bleeding from the bladder or urethra is usually bright red or pink.

Painless passage of visible blood in a child also suggests an upper urinary tract source of the bleeding. Visible blood in the urine from a lower urinary tract problem is almost always painful in a child. This is not the case for an adult, in whom a bladder tumor might present with painless macroscopic hematuria. Bladder tumors are rare in childhood.

When the passage of visible blood is associated with pain, the location of the pain usually indicates the source of the bleeding. Flank or low back pain suggests an origin in the kidney; suprapubic pain, an origin in the bladder; and urethral pain, an origin in the urethra.

What Would You Do Now?
A. Reassure the boy and his mother that because the urine test did not reveal anyblood, there was no need for concern.
B. Prescribe an antibiotic for a presumedurinary tract infection.
C. Order blood tests to determine the completeblood cell count and levels of antistreptolysinO, third component of complement,creatinine, electrolytes, total protein andalbumin; and perform a throat swab forgroup A β-hemolytic streptococci.
D. Order an ultrasonogram of the kidneys andbladder.
E. Order a voiding cystourethrogram.

The Consultants' Choice:

Option D

We recommend obtaining an ultrasonogram of this patient's kidney and bladder to screen his urinary tract for structural abnormalities, such as hydronephrosis, kidney stones, echogenicity changes suggestive of glomerulonephritis, and neoplasms.

We do not recommend:

•Reassurance; bleeding in the urinary tract always deserves investigation.
•Treatment with an antibiotic, because this patient had no symptoms of fever, flank pain, dysuria, or voiding dysfunction.
•Investigations for glomerulonephritis at this stage, since the visible blood lasted for only one void, there is no proteinemia, and the boy does not have evidence of hypertension, edema, or other signs of fluid overload.
•A voiding cystourethrogram since the history suggests an upper tract origin of the bleeding.

With further questioning, the boy reveals that he saw the Coca-Cola-colored urine on one previous occasion but did not tell his mother. The first episode was about a month earlier; it occurred after a karate class during which the boy had sustained kicks to his flanks. On that occasion, the blood was also visible for only one void. Between the karate class and the clinic visit the urine had been otherwise clear.

Ultrasonography of the urinary tract revealed 2 kidneys, normal in size, shape, position, and echogenicity. A 6-mm stone was seen in the upper pole of the right kidney. Acoustic shadowing, typical of a stone, was present. The bladder was normal.

What Would You Do Now?
A. Ask the mother if there is any family historyof kidney stones.
B. Ask the boy to collect a midstream urinefor culture, and a 24-hour urine collection todetermine levels of creatinine, calcium,oxalate, citrate, uric acid, sodium, and cystine.
C. Ask the mother to document a 3-day foodand fluid diary.
D. Order blood tests to determine levels ofcreatinine, urea, electrolytes, calcium,phosphorus, alkaline phosphatase, anduric acid.
E. All of the above.

The Consultants' Choice:

Option E

We recommend all of the above options.

This patient's painless Coca-Cola-colored urine was the result of a stone in the upper pole of the right kidney. Stones are often painless until passed into the pelvis and ureter. Bleeding might occur after vigorous exercise, especially with contact sports--presumably when the hard and often sharp and irregular surface of the stone irritates the surrounding renal parenchyma. The voided blood is usually hemolyzed during transit through the renal tubular system and therefore is dark-colored and often confused with that from glomerulonephritis. The blood is typically only visible for a solitary void, since hemostasis prevents further bleeding. Macroscopic hematuria in children with acute glomerulonephritis typically lasts at least several days.

In children and adults who live in North America, stones are usually composed of calcium. A family history may be present. Hypercalciuria is a potential familial cause of kidney stones and can be inherited in an autosomal dominant fashion. Cystinuria, hyperuricosuria, and hyperoxaluria are uncommon causes of pediatric urolithiasis. These disorders are often inherited in an autosomal recessive fashion. Some causes of renal tubular acidosis--another potential and uncommon cause of urolithiasis--are inherited.

Proving the chemical composition of a stone is important in that further investigation and therapy are based on this analysis. Stone analysis is the gold standard. A 24-hour urine collection for possible chemical constituents is only helpful if the results are abnormal; often they are not. Because calcium stones are so common, some experts recommend obtaining only a 24-hour urine collection for calcium and creatinine levels as a preliminary study. A midstream urine specimen for culture is useful because urinary tract infection can be a cause as well as a complication of renal stones.

A 3-day food and fluid diary is helpful to assess the calcium content of the diet and to determine whether fluid intake is adequate. Low fluid intake can predispose to stone formation. Children with calcium stones should be counseled to ingest the recommended daily allowance of calcium and vitamin D for their age. These children should take neither too much nor too little, and should not overdo either salt or protein in the diet--both of which increase urinary calcium excretion.

Blood tests are necessary in addition to 24-hour urine studies to further investigate the cause of the kidney stone. Children with a kidney stone should be referred to a pediatric nephrologist or pediatric urologist for ongoing investigation and treatment.

References:

FOR MORE INFORMATION:

Gillespie RS, Stapleton FB. Nephrolithiasis in children. Pediatr Rev. 2004;25: 131-139.