Infectious mononucleosis, mono, is an illness that can present with a variety of symptoms. While fatigue, sore throat, and swollen lymph nodes are widely recognized signs, a less common but possible symptom is dark urine. This particular change in urine color is not a direct result of the viral infection itself, but rather a potential complication involving the liver. If dark urine occurs with mono, it signals a potential liver issue.
How Mono Affects the Liver
Infectious mononucleosis is most frequently caused by the Epstein-Barr virus (EBV), a common human herpes virus. While EBV primarily affects lymphocytes, it can also influence liver function. Many individuals with mono experience mild liver inflammation (hepatitis), often with elevated liver enzymes. This inflammation indicates that the liver is under stress from the viral infection.
When the liver becomes inflamed, its ability to process bilirubin, a yellow pigment produced during the normal breakdown of red blood cells, can be impaired. Normally, the liver processes bilirubin and excretes it into bile, which then passes into the intestines. However, with liver inflammation, bilirubin can accumulate in the bloodstream. This excess bilirubin then gets filtered by the kidneys and is excreted in the urine, causing it to appear unusually dark.
Liver involvement is common in mono, often leading to elevated liver enzymes. However, significant bilirubin abnormalities and jaundice (yellowing of skin and eyes) are less frequent.
Understanding Dark Urine
Dark urine, particularly a brown or tea-like color, often indicates the presence of bilirubin, signifying a potential issue with liver function or bile ducts. This specific dark coloration is distinct from the darker yellow or amber urine that results from dehydration, which is simply concentrated urine due to insufficient fluid intake. When bilirubin is excreted through the kidneys into the urine, it creates a dark, sometimes foamy appearance.
Other factors can also cause urine to darken, such as consuming certain foods like fava beans or rhubarb, or taking specific medications. However, when dark urine is tea-colored and persists, especially with mono, it suggests an underlying metabolic process involving the liver and bilirubin.
When to Consult a Doctor
Experiencing dark urine, particularly a brown or tea-colored shade, warrants medical evaluation, especially if it occurs during or after an illness like mono. While liver involvement in mono is often mild and resolves on its own, it is important to rule out more significant issues. A healthcare professional can determine the exact cause of the dark urine and recommend appropriate management.
It is especially important to seek medical attention if dark urine is accompanied by other concerning symptoms. These can include yellowing of the skin or eyes (jaundice), abdominal pain, nausea, vomiting, or persistent fatigue. These signs may indicate a more pronounced liver issue that requires a professional assessment to ensure proper diagnosis and care.