‘Pink’ Urine Under UV Light Cued AHP in Pregnant Woman
A young pregnant woman was diagnosed with acute hepatic porphyria (AHP) after her urine was found to glow pink under ultraviolet (UV) light, as described in a recent case report.
The woman’s symptoms were general, which often makes an early diagnosis difficult. A “simple method like urine examination under ultraviolet light should be used to accelerate the diagnosis,” the investigators wrote.
The report, “Pink urine as an inkling for a diagnostic dilemma: acute hepatic porphyria,” was published in the journal BMJ Case Reports by a team in India.
Porphyrias are a group of disorders caused by the lack of specific enzymes that are required for making heme — a compound that is part of hemoglobin, the protein that carries oxygen in red blood cells, and other important proteins in the body. These enzymes work one after another in a step-wise manner, converting intermediate compounds (porphyrins) into the final product (heme). If one enzyme fails, porphyrins and porphyrin precursors can accumulate to toxic levels.
Diagnosing porphyria usually involves genetic testing and measuring the levels of porphyrins or porphyrin precursors in the urine, blood, or feces. One of the most common tests detects porphobilinogen, a porphyrin precursor, in the urine. However, this test may have false-positive results, as noted by researchers.
Due to a chemical reaction called oxidation, porphyrins’ presence in urine can also be detected by placing samples under UV light. When porphyrins are present, urine acquires a distinctive fluorescent pink color.
“Simple, efficient, time-effective and cost-effective methods like first-line examination of urine sample under ultraviolet light have a potential role in investigating these rare diagnostic dilemmas under appropriate clinical suspicion,” the investigators wrote.
They reported the case of a 23-year-old pregnant woman who was diagnosed with AHP based on a urine test that used UV light.
The woman was six weeks pregnant. For three days she had been experiencing pain spread across her abdomen, with cramps occurring at irregular intervals. She also had generalized weakness in her arms and legs.
Her eyelids were pale, but the results of a physical and a blood workup were otherwise normal.
An ultrasound scan of her abdomen excluded the possibility of an ectopic pregnancy (when a fertilized egg grows outside the womb), molar pregnancy (when a non-viable fertilized egg or a mass of tissue from the placenta grows in the womb), or early pregnancy loss.
When doctors examined a sample of her urine under UV light, the urine appeared fluorescent pink, indicating oxidation of porphobilinogen into porphobilin, another porphyrin precursor. The fluorescent pink color disappeared in urine samples taken after her acute symptoms resolved.
At this point, she was diagnosed with acute hepatic porphyria. Acute AHP attacks are marked by the sudden appearance of symptoms, ranging from abdominal pain to muscle weakness and mental changes. These attacks can be precipitated by certain medications, alcohol, and other factors, such as stress and fasting.
“Variable, non-specific presentation makes acute hepatic porphyria a diagnostic challenge,” the investigators wrote.
“I believe that I am currently doing well and am able to carry out my tasks normally,” the patient said after learning of her diagnosis. “I am also aware that a few precipitating factors could lead to acute attacks and shall try to avoid them.”