Acute Porphyria Attack Initially Treated as Early Reaction to Pregnancy

Abdominal pain and nausea in a woman having an acute porphyria attack was initially misdiagnosed as a natural response to the early stages of a pregnancy, a recent case study reported.

Her case, its authors noted, highlighted the importance of performing urine screening tests whenever porphyria is suspected, and starting treatment as soon as possible if test results are positive.

The report, “Acute porphyria presenting as abdominal pain in pregnancy,” was published in the journal CMAJ.

The woman, a 29-year-old Caucasian, went to the hospital after experiencing sudden lower abdominal pain, accompanied by nausea, vomiting, and diarrhea.

Upon examination, she was found to be pregnant for about a month. Her symptoms were initially presumed to be secondary to pregnancy (i.e., morning sickness), and she was discharged from the hospital.  Her symptoms continued to worsen, however, and she was re-admitted to the hospital a few days later.

Her pain continually worsened, requiring treatment with opioids. She also developed high blood pressure and urinary hesitancy (difficulty urinating), which were treated symptomatically. She was also given several medications (pyridoxine-doxylamine, dimenhydrinate, and metoclopramide) to ease nausea.

A battery of laboratory tests were performed, and most came back within normal ranges. Various tests for infectious diseases, including chlamydia, gonorrhea, and COVID-19, came back negative. Tests for key inflammatory markers were also normal, showing that an autoimmune disease was unlikely to be the cause of her symptoms.

The patient’s healthcare team was initially working under the belief that her pain could be due to a previous appendix surgery. However, given symptoms that included severe abdominal pain and high blood pressure, porphyria was considered as a potential explanation.

Her physicians ordered a urine screening test, which came back positive.

“We diagnosed acute porphyria, likely triggered by pregnancy,” the scientists wrote. Additional urine and stool tests ended up confirming the woman had hereditary coproporphyria (HCP). HCP is a form of acute porphyria that tends to manifest in adulthood and is often triggered by certain environmental factors, which may include hormonal changes associated with pregnancy.

She rapidly started on Panhematin, an approved treatment to ease attacks of acute intermittent porphyria (AIP) related to the menstrual cycle. At the same time, physicians stopped her anti-nausea medications, as these can further worsen porphyria attacks. The woman was also prescribed a high-carbohydrate diet.

After four days, her symptoms eased. She was discharged from the hospital on low-dose opioids, which she soon discontinued.

At follow-up one month later, the patient’s nausea and abdominal pain had eased, and her blood pressure was within normal limits. Later genetic tests confirmed the patient and her father both carried a mutation known to be associated with HCP, though the father had never experienced symptoms.

As the woman’s pregnancy progressed, she was monitored for signs of her symptoms returning, and her healthcare team made an effort to avoid medications that might trigger an attack.

“The patient delivered a healthy baby,” the researchers reported.

They noted that changes in hormone levels, which can occur during pregnancy, are a known trigger of porphyria, potentially explaining why the woman started experiencing symptoms about four weeks into her pregnancy.