Dark Urine
David Munson
Approach to the Patient with Dark Urine
I. Definition of the Complaint
Very concentrated urine appears dark in the setting of dehydration, but it is
unusual for this to be the primary complaint of the patient. In order for a
child or parent to complain of dark urine specifically, there is usually an
additional descriptor. The patient may elaborate that the urine is
“tea colored,” “Coca-Cola colored,” bloody, or a particular color. It is these characterizations that help to guide
the development of a differential diagnosis. The presence of myoglobin or
hemoglobin is frequently responsible for the dark appearance of urine.
Porphyria, blackberries, beets, food coloring, and certain medicines such as
Pyridium (phenazopyridine) can give urine a reddish appearance. Urate crystals
are a common cause of reddish urine in newborns.
Serratia marcescens can grow on wet diapers and produce “red diaper syndrome.” Dark brown or black urine can result from aminoacidopathies such as
tyrosinemia.
II. Causes of Dark Urine
The causes of dark urine are most easily grouped by etiology: (a) frank blood;
(b) myoglobinuria; (c) infectious; (d) medications; (e) food/dyes; or (g)
metabolites (Table 20-1).
III. Clarifying Questions
The generation of an appropriate differential diagnosis for a patient who
complains of dark urine is guided by a careful history. Age at onset,
associated symptoms, prodromal illness, recurrence of symptoms, available
medications in the house, and family history lead to an appropriate workup.
• What is the age of the patient?•
— There are very few causes of dark urine in an infant. Urate crystals associated
with dehydration can cause a red tinge to the diaper, and trauma from a
catheter or suprapubic tap can cause minor bleeding. Renal vein thrombosis and
congenital anomalies should also be considered. Hereditary nephritis typically
manifests before 3 years of age. If the patient is an exploring 2-year-old,
ingestions should be considered. School age children are classically affected
by poststreptococcal glomerulonephritis. Teenagers are more likely than younger
patients to experience symptoms of rheumatologic diseases.
• Was there a prodromal illness?
— Acute glomerulonephritis most commonly occurs 10 days after streptococcal
pharyngitis. Immunoglobulin A (IgA) nephropathy and benign recurrent hematuria
are usually associated with a respiratory tract infection. Influenza and sepsis
syndrome have rarely been associated with rhabdomyolysis. Prolonged malaise and
weight loss prompt consideration of a chronic disease such as Wilms tumor or
Wegener granulomatosis.
• Is the patient having pain?
— Flank pain can be an indication of a renal stone and is also sometimes seen
with benign recurrent hematuria. Headaches may indicate severe or prolonged
hypertension or significant kidney disease. Diffuse muscle pain and tenderness
are seen with rhabdomyolysis.
• Has this happened before?
— Hereditary nephritis usually occurs for the first time before 3 years of age.
Benign recurrent hematuria and IgA nephropathy are both recurring illnesses.
• Is the patient complaining of swelling?
— Edema generally indicates significant kidney disease and may be seen in
disorders such as glomerulonephritis and renal vein thrombosis.
• Has there been a change in the pattern of urination?
— Frequency and urgency are good indications of a urinary tract infection, and
hemorrhagic cystitis should move high on the list. New enuresis in a
toilet-trained child may be an early indication of urinary tract infection as
well. Oliguria is a concerning sign and may indicate progressive
glomerulonephritis or severe illness such as sepsis syndrome.
• Is there a family history of similar symptoms?
— Hypercalciuria usually affects multiple family members. With hereditary
nephritis, there should be a positive family history. Some rare metabolic and
mitochondrial disorders can manifest as rhabdomyolysis in the setting of
exercise or febrile illness in multiple family members.
• Is the patient taking medications? What medications are in the house?
— Prescribed medications such as ibuprofen, deferoxamine, and Pyridium can
discolor the urine. Rifampin, used in the management of tuberculosis and as
prophylaxis after exposure to a patient with
Neisseria meningitidis infection, also colors the urine a red-orange. Because it is important to assess
all medications that might be available to a curious child, a thorough
inventory of medications used by any household members should be taken.
• Has the child been eating anything that could account for a change in urine
color?
— In an asymptomatic patient, food dyes and some common foods such as beets and
blackberries may discolor the urine.
• Has the patient been involved in extreme exercise?
— In an extreme case, exercise can induce rhabdomyolysis. More commonly,
long-distance runners may experience transient frank hematuria. Assessing a
teenager
's involvement in a sport that involves significant running may clarify the
diagnosis. These patients are otherwise asymptomatic.
Pictures
Book Source Details
- Book Title: Pediatric Complaints and Diagnostic Dilemmas
- Author(s): Samir S Shah MD; Stephen Ludwig MD
- Year of Publication: 2003
- Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2008 Williams & Wilkins.
More About Causes of Darkened urine
» Next page: Dark Urine - Case 20-1: 1-Day-Old Boy (Pediatric Complaints and Diagnostic Dilemmas)
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