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Image from Wikimedia Commons | Rmosler2100.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

The above urine sample, tinged with green, was obtained from a patient following 6 days of moderately high-dose propofol sedation. The green color, a rare side effect of propofol, may be the result of phenolic metabolites of the drug.[1]

The coloration of normal urine varies from light yellow to pale amber; however, a multitude of pathologies and agents can change the color and/or clarity of urine. This presentation discusses potential causes of abnormal urine color.

Image of gross hematuria courtesy of Josh Palka, DO.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Hematuria

The urine bag shows gross hematuria in an elderly man with a malpositioned Foley catheter; the catheter balloon was found to be inflated in the prostatic urethra.

Hematuria, defined as the presence of red blood cells (RBCs) in the urine,[2] is one of the most common urologic problems that urologists encounter. It may present microscopically (defined as three or more RBCs per high-powered field) or be grossly visible to the naked eye, with the potential source of the RBCs ranging from the renal glomerulus to the urethral meatus.[2]

Hematuria can vary in appearance from a light pink or peach color to a dark port wine color, depending on the severity of bleeding.

The myriad of genitourinary pathologies that cause hematuria range from benign conditions such as vigorous exercise to much more concerning etiologies such as bladder or kidney cancer. Once benign conditions have been ruled out, further evaluation is required.[2]

Image of gross hematuria courtesy of Josh Palka, DO.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

The workup of hematuria per American Urological Association guidelines includes imaging of the upper urinary tracts. This is performed via computed tomography urography (CTU) (criterion standard) or noncontrast renal CT scanning, noncontrast magnetic resonance imaging, or ultrasonography with retrograde pyelography.[2] These imaging modalities are used to evaluate for renal carcinoma or upper tract urothelial carcinoma. Other etiologies such as renal angiomyolipoma can also be evaluated with CT.

CT and ultrasonographic scanning are not sensitive or specific enough to evaluate the bladder for carcinoma in situ; such assessment is therefore performed by direct visualization, via cystoscopy. Urinary cytology may be useful as an adjunct to help rule out malignant changes within the urinary tract after an initially negative evaluation or in patients with risk factors for carcinoma in situ (smoking) and irritative voiding symptoms.[2]

Image of Escherichia coli growing on agar from Wikimedia Commons | LenkaM. [Creative Commons ShareAlike 1.0 Generic license (CC by-SA 1.0).]

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Urinary tract infections

Urinary tract infections (UTIs) may also lead to hematuria.[2] Escherichia coli is one of the most common causative organisms.[3] In a population study looking at 40,618 UTI episodes in the Calgary region of Canada, E coli was isolated in approximately 74.2% of ambulatory patients, 65.5% of hospitalized patients, and 46.6% of nursing home patients.[4]

Treatment for acute, uncomplicated cystitis consists of antibiotic therapy, commonly with trimethoprim-sulfamethoxazole, nitrofurantoin, or fosfomycin.[3]

Ciprofloxacin is no longer recommended for uncomplicated UTIs. A May 2016 US Food and Drug Administration (FDA) safety communication warned of potential disabling adverse effects associated with the use of fluoroquinolones for these and other uncomplicated conditions.[5]

Image of a right grade IV renal laceration courtesy of Josh Palka, DO.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Trauma

Another etiology of gross hematuria is genitourinary trauma. Shown is a 67-year-old man who presented to the emergency department as a pedestrian-versus-automobile accident.

An abdominal and pelvic CT scan with IV contrast was obtained and revealed a right grade IV renal laceration through the collecting system and active extravasation from the posterior of the right kidney, in addition to other polytrauma.

In trauma, the kidney is the most often injured genitourinary organ. Trauma to the kidneys can be managed conservatively, and, if needed, angioembolization of the kidney can be performed. Surprisingly, the degree of hematuria does not correlate well with the severity of the trauma. Renal lacerations are graded from one to five, with one being the least severe and five being the most severe. Details are listed on the American Association for the Surgery of Trauma website.

The patient shown developed a delayed bleed and underwent angiography with selective embolization. He was stabilized and discharged home after follow-up imaging revealed no further bleeding.

Image of purple urine bag syndrome (PUBS) courtesy of Chris Atalla, DO.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Purple urine bag syndrome

Purple urine bag syndrome (PUBS) is a rare phenomenon caused when UTIs with bacterial strains that produce indoxyl phosphatase (eg, Providencia stuartii, Providencia rettgeri, Klebsiella pneumoniae) react with the synthetic materials of urinary catheters/bags.[6]

When PUBS occurs, it is typically found in elderly patients with constipation and long-term, indwelling urinary catheters, in association with colonization with the above bacteria as well as with E coli, Morganella morganii, Pseudomonas aeruginosa, and Proteus and Enterococcus species.[6]

Clinicians should keep in mind that PUBS is not entirely a benign condition, because it points to underlying recurrent UTIs and, potentially, the improper care of urinary catheters and/or improper hygiene.[6,7]

Image of bladder cancer in a patient with painless gross hematuria, courtesy of Josh Palka, DO.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Malignancy

The image reveals bladder cancer found in an elderly man, a former smoker, who presented with a 4-month history of painless gross hematuria.

A major concern for patients with gross hematuria is the possibility of urothelial cancer in the bladder or the upper tract of the collecting system. Globally, urothelial bladder cancer is the seventh most common cancer in men and the seventh most common neoplasm in women.[8] Smoking or a previous history of smoking is the most common risk factor for this disease.[8] Commonly, patients present with complaints of irritative voiding symptoms (eg, dysuria, hematuria, urinary frequency) that may mimic UTI, but with no growth found on urine cultures. It is imperative that patients be further evaluated with cystoscopy to ensure that no underlying malignancy, such as carcinoma in situ, is missed.

Additionally, patients on anticoagulation therapy should be evaluated similarly to those not on such treatment, as spontaneous hematuria from blood thinners alone should not occur and may indicate an underlying malignancy.

Image of right renal mass courtesy of Josh Palka, DO.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Another potential cause of hematuria is renal cell carcinoma (RCC), which accounts for 2-3% of all cancers in the United States and about 85% of malignant kidney tumors.[9] RCC is also the sixth and eighth most common cancer in US men and women, respectively.[9]

The image shows a CT scan concerning for a right renal mass (blue star). Final pathology after a right-sided nephrectomy revealed it was clear cell RCC.

Obesity is a risk factor for, and has a linear relationship with, RCC, especially in women. Additionally, individuals with von Hippel-Lindau syndrome are at higher risk for RCC; up to 30% develop this malignancy, with nearly 70% of affected patients having RCC by age 60 years. RCC is also a major cause of death in these patients.[10]

Nephron-sparing surgery is the treatment of choice for smaller RCC tumors, with one case series showing no local recurrence.[11] This type of procedure is more technically difficult to perform and requires the proper selection of patients.[12]

Image courtesy of Josh Palka, DO.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Benign prostatic hyperplasia

The image shows a transurethral resection of the prostate (TURP) in progress, with a bipolar loop used to remove prostate tissue in order to open the urethral channel and cauterize any bleeding vessels identified.

Benign prostatic hyperplasia (BPH) is another common cause of gross hematuria, owing to the vascularity of the primary gland itself or because of vascular prostatic regrowth after TURP.[13] An indication for TURP is gross hematuria that is not amenable to medical therapy with 5-alpha-reductase inhibitors.[13] This procedure may be especially helpful in men with larger prostates (>30-40 g).[14] A highly efficient and effective alternative surgery is prostate enucleation, which can be performed with either holmium or thulium laser energy (HoLEP or ThuLEP). This procedure can be carried out on significantly larger prostates endoscopically, requiring no incisions (similar to TURP), with a low complication rate and long-lasting results.[15]

Image of ureteral stones removed with laser lithotripsy from a patient with left flank pain and hematuria, courtesy of Josh Palka, DO.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Nephrolithiasis

Kidney stones are one of the most common hematuria-causing pathologies. A study using the National Health and Nutrition Examination Survey (NHANES; 2015-2018) found the prevalence of kidney stones in the United States in persons over age 20 years to be 11.0%.[16] Multiple risk factors exist for kidney stone formation—several are metabolic and/or dietary in nature.

Obesity is a known risk factor, with the incidence of kidney stone disease having been found to rise with the incidence of obesity.[17]

One frequent dietary cause of nephrolithiasis is inadequate fluid intake.[18,19] Another is increased intake of oxalate from foods such as black tea, dark chocolate, rhubarb, spinach, and certain types of nuts.[20] Patients with recurrent kidney stone formation should undergo a metabolic evaluation and 24-hour urine study to elucidate any potential reversible causes of their stones.

Image of myoglobinuria after a high-voltage electrical injury that resulted in rhabdomyolysis, courtesy of Nunn R, Chang N, Milner SM, Price LA. Eplasty. 2013;13:ic16. [Open access.] PMID: 23409207, PMCID: PMC3558850.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Myoglobinuria

Myoglobinuria usually results from rhabdomyolysis, which can arise from trauma or alcohol/drug abuse.[21] The tea-colored urine that develops is commonly confused with gross hematuria by the untrained eye. These two conditions can be differentiated by centrifuging the urine. If the urine has a clear center, the cause of the discoloration is myoglobinuria, whereas if there is a reddish sediment, the etiology is likely hemoglobinuria.[21] Creatine kinase levels are also typically elevated in myoglobinuria.

Rhabdomyolysis presents with nonspecific findings, of which the three hallmarks are muscle weakness, myalgia, and dark urine.[21] Clinical suspicion is paramount to avoidance of potentially life-threatening complications such as acute kidney injury and disseminated intravascular coagulation.[21,22]

Obtain creatine kinase and electrolyte levels and assess renal function by measuring blood urea nitrogen (BUN) and creatinine.

The main therapeutic goal in patients with rhabdomyolysis is hydration for prevention of acute kidney injury, with preservation of kidney function.[21,22]

Image of pyuria courtesy of Josh Palka, DO.

9 Causes of Discolored Urine

Josh Palka, DO; Christopher S Atalla, DO | December 20, 2022 | Contributor Information

Pyuria

Any patient with a long-term, indwelling urinary catheter is almost guaranteed to have bacteriuria,[23] which may develop into pyuria, wherein white blood cells (or pus) are present in the urine.

The pyuria shown occurred in a T5 paraplegic man with a chronic suprapubic tube.

To minimize the risk of infection, urinary catheters and suprapubic catheters should be changed every 3-4 weeks.[24] When possible, bladder emptying should be managed with clean, intermittent catheterization to reduce the risk of bacteriuria and infection.[23]

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