A 30-year-old woman with SLE was admitted to the emergency department because of abdominal pain.
On September 15, 2020, she developed a sore throat and cough and was subsequently treated with roxithromycin, ambroxol, and Honghua (a kind of Chinese traditional medicine). On September 17, acute and severe abdominal pain and cramping developed, with concomitant left low back pain, vomiting, and dysuria but no venting or defecation. She presented to a local hospital, where a clinical diagnosis of intestinal obstruction was made and fasting, gastric intubation, and support treatments were prescribed. The patient felt no release of abdominal pain and was transferred to the emergency department of this hospital on September 22. She had a background of pulmonary tuberculosis twenty years ago and was treated with isoniazid and rifampicin for two years. The patient was diagnosed with immune thrombocytopenia (ITP) in 2002, she suffered from frequent hemorrhage for ten years and finally underwent splenectomy in 2012, and she presented with an itchy rash on her face and limbs after exposure to sunlight in 2014. Autoantibody testing showed that antinuclear antibody (ANA) was elevated (1 : 640); Sm, SSA, RO 52, and Scl 70 antibodies were positive, while double-stranded DNS (ds-DNA) antibodies were negative. No other organ involvement was noticed. She was diagnosed with SLE and administered hydroxychloroquine (HCQ, 0.4 g/d) and prednisone (7.5 mg/d). Her last menstruation began on September 20, exactly the third day after abdominal pain developed. She denied any alcohol, tobacco, or drug abuse. Her family history was significant for lung cancer (mother died of lung cancer).
On admission, oral examination revealed oral mucosal dryness and bleeding and several lower lip mucosa ulcers. The abdomen was soft, with decreased bowel sounds, and tenderness was noticed around the bellybutton. Laboratory studies revealed hyponatremia (128 mmol/L) and increased C-reactive protein (14.07 mg/L). Liver enzymes, bilirubin, albumin, creatinine, uric acid, glucose, cholesterol, serum amylase and lipase, thyroid tests, erythrocyte sedimentation rate, and complement (C3 and C4) tests were normal. Antinuclear antibody (ANA) levels were elevated (1 : 160), SSA 60 and RO 52 antibodies were positive, and double-stranded DNA (ds-DNA) and other nuclear antigen antibodies were negative. Electrocardiogram showed sinus tachycardia. Abdominal and pelvic CT scans revealed a soft tissue signal behind the uterus and a suspicious small stone at the pelvic part of the ureter. Tramadol and chlorpromazine were administered to control the abdominal and back pain. Therapy was initiated with ertapenem (1 g/d) and methylprednisolone (0.5 mg/kg body weight) because of the infection, and the medication prescribed for SLE was suspended because of the sudden onset of symptoms. Oral laxative and intravenous infusion of 10% glucose and saline were administered due to suspicious intestinal obstruction.
The patient presented with worsening weakness and dysuria after 24 hours of admission. Reddish urine was noticed after indwelling a urinary catheter. This finding raised the suspicion of acute porphyria. The urine turned a dark brown color after one hour of exposure to sunlight (Figure 1). The urobilinogen level was 33 mumol/L (reference range, 3 to 16 mumol/L), and the uroporphyrinogen (UPG) and porphobilinogen (PBG) tests were positive. Free erythrocyte protoporphyrin (FEP) was 5.3 mug/gHb (reference range, 0 to 4.7 mug/gHb). Brain magnetic resonance imaging did not reveal any pathologic features.
Based on these findings, we made a tentative diagnosis of acute porphyria. Ertapenem and methylprednisolone were stopped as the neutrophil levels returned to normal. Sufficient glucose support (250-300 g/d), restriction of liquids (<2500 mL/d), and moderate sodium supplements were administered. Morphine (5 mg) was given to relieve pain when necessary. Hydroxychloroquine (0.4 g/d) and prednisone (7.5 mg/d) were restarted for SLE. Within a four-month follow-up, no abdominal symptoms were observed.
Based on these findings, we decided to examine the genetic causes of the disease in her family.