Basic urine test helps doctors in Sri Lanka diagnose rare porphyria
Test may aid AHP diagnosis in resource-limited settings, researchers say
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A basic urine test helped doctors in Sri Lanka diagnose probable acute hepatic porphyria (AHP) in a woman with recurrent unexplained abdominal pain, according to a case report that highlights the challenges of identifying the rare disorder in settings with limited access to specialized diagnostic tests.
The diagnosis was supported by urine analysis using spectrophotometry, a laboratory technique that identifies and quantifies substances by measuring how they absorb light. The test revealed elevated levels of porphyrins in the urine, substances that can accumulate to toxic levels in people with the condition.
“This case illustrates the diagnostic value of clinical suspicion supported by basic biochemical testing in identifying probable acute hepatic porphyria in a resource-limited setting,” wrote Mihiran Thanigasalan, MD, a doctor at the National Hospital of Sri Lanka.
Thanigasalan detailed the case in the study, “Probable Acute Hepatic Porphyria Diagnosed Using Urinary Porphyrin Spectrophotometry in a Resource-Limited Setting: A Case Report,” published in Cureus.
Porphyrias are a group of rare genetic disorders, each caused by a specific mutation that disrupts the body’s ability to produce heme, a molecule needed for red blood cells to carry oxygen. When this process is impaired, intermediate heme-making molecules — known as porphyrins and their precursors, including delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) — can accumulate in the body.
Specialized tests for porphyria diagnosis
AHP comprises four types of porphyria marked by sudden attacks that vary in severity. AHP symptoms may include intense abdominal pain, nausea, vomiting, constipation, and neurological issues. Because physical examinations and routine laboratory tests often appear normal during these episodes, diagnosis is challenging and often delayed.
Diagnosis typically relies on measuring PBG or ALA levels in urine, followed by genetic testing. However, access to these specialized tests is limited in many lower-income countries, so doctors often rely on clinical features and basic laboratory methods.
The woman in the case report had no relevant family history. She sought medical care after three days of moderate to severe abdominal pain, mainly affecting the central and lower abdomen, accompanied by nausea, vomiting, and loose stools. She also reported intermittent constipation over the previous seven months.
She had experienced several similar episodes in the past that required hospital treatment. These previous attacks were diagnosed as constipation or ureteric colic, a type of severe pain usually caused by kidney stones. She had occasional, milder episodes that didn’t require medical attention.
Despite the severity of her symptoms, physical and neurological examinations showed no clear abnormalities, and doctors found no signs of problems with the body’s automatic functions, such as abnormal heart rate, blood pressure, or excessive sweating. Routine blood tests and imaging scans were largely normal.
Because the woman had repeated episodes of severe abdominal pain without an obvious cause, doctors began to suspect AHP.
They first performed a Hoesch test, a rapid urine test used to screen for increased PBG levels. The test turned out positive. Urine analysis using spectrophotometry then showed high total porphyrin levels in the urine, along with a characteristic Soret peak, a light-absorption signal consistent with porphyrin compounds.
After ruling out other conditions that can increase urinary porphyrins, including liver disease, red blood cell destruction, alcohol abuse, and lead poisoning, doctors made the diagnosis of probable AHP.
“Marked elevation of urinary PBG is required to establish the diagnosis of an [AHP] attack,” Thanigasalan wrote, noting that isolated increases in urinary porphyrins are nonspecific and must be interpreted alongside clinical findings and PBG testing. “In this patient, a positive Hoesch test, elevated urinary porphyrins, and a characteristic Soret peak provided biochemical support for the diagnosis.”
However, the lack of quantitative measurements of urinary ALA and PBG and genetic testing limited “definitive subtype classification,” he wrote.
Since standard treatments for acute porphyria attacks were not available at the hospital, the woman received supportive care instead. This included pain-relieving medications, a carbohydrate-rich diet, and dextrose (sugar) infusions. Increasing carbohydrate intake can help reduce the liver’s production of porphyrin precursors, easing symptoms during an attack.
The woman’s abdominal pain and digestive symptoms gradually eased. Before leaving the hospital, she received counseling about the condition, including advice to avoid certain medications and other triggers that can provoke attacks, and to maintain adequate carbohydrate intake during milder episodes.
During six months of follow-up, the woman did not experience any further severe attacks.
“Acute porphyria should be considered in patients with recurrent severe abdominal pain and minimal objective findings after exclusion of common causes,” Thanigasalan concluded. “In resource-limited settings, careful clinical evaluation combined with basic urinary porphyrin testing can support timely diagnosis, allowing appropriate management and prevention of serious complications.”
