A 15-year-old Hindu Nepalese schoolgirl presented to the Paediatric Emergency Department at Tribhuvan University Teaching Hospital with the complaint of severe abdominal pain for the last few days accompanied by headache, nausea, vomiting, limb pain, and constipation.
The patient had similar episodes of acute abdominal pain twice before with no definite diagnosis explaining her pain. Four months ago, she had her first episode of abdominal pain, for which she was admitted to a private tertiary care hospital in Biratnagar for a presumed Intestinal Obstruction due to fecal impaction.
In the second trivia of pain, she was again admitted to another private tertiary care hospital in Kathmandu for abdominal pain, constipation, pain in limbs, and hypertension. According to the informant, the patient was essentially well 4 days before admission. The patient stated that the abdominal pain was acute at the onset, originating at the left hypochondrium, which was non-radiating, colicky, and burning in nature at the same time with waxing and waning intensity. She also complained of multiple episodes of vomiting which was non-bilious and non-bloody in character, accompanied by loss of appetite. Also, she complained of intermittent constipation for the past 3 months and a history of passing stool only once a week. There was no history of fever, cough, headache, weight loss, progressive paleness, swelling of the body, haematuria, and loss of consciousness. During her stay at the hospital, she was admitted to PICU for 3 days. Labetalol infusion was started for acute severe hypertension. She also had episodes of generalized tonic–clonic seizure, which was managed with anti-epileptics. In the laboratory test, the patient was found to have hyponatremia. A presumed diagnosis of Gitelman Syndrome with chronic constipation and refractory hypokalemia was made. Apart from these, the patient did not have any other significant past medical history. She was then referred to our center for further management.
She was admitted to Tribhuvan University Teaching Hospital (TUTH) Paediatric Emergency on 20th August 2022. On examination, the patient was alert and well-oriented and she had no pallor, icterus, cyanosis, lymphadenopathy, or edema. There was no blistering, scarring, or erythema on the skin either. Detailed family history revealed no significant inherited disorders. Likewise, there was no relevant past surgical, social or psycho-social history recorded in our case. Her menstrual history elucidated she had oligomenorrhea but no significant precipitation of symptoms related to her current illness.
On admission, her vitals on examination were; blood pressure (180/100 mmHg), respiratory rate (20 bpm), SpO2 (92%), pulse rate (100 bpm), and normal respiratory and cardiovascular system examination. Per abdominal examination, a mildly tender abdomen was noted, while no organomegaly and renal bruits were noted. CNS examination showed the patient was normal with a Glasgow Coma Scale (GCS) of 15/15. Comprehensive blood count was within the normal limits at the time of admission except for a mild anemic picture with a hemoglobin of 10.9 g/dl.
For the management of hypertension, amlodipine was started. Polyethylene glycol was given for constipation. 3% NaCl infusion followed by oral salt replacement was started to correct sodium levels. However, persistent hyponatremia (up to 109 mEq/L) was the area of concern along with hypomagnesemia (ranging from 1.1 to 2.4 mg/dl). It raised the speculation of disturbance in the renin–angiotensin–aldosterone system. After laboratory analysis, serum aldosterone was 45.94 ng/dl (3.1–35.1 ng/dl in the upright position), direct renin 161.73 µIU/ml (4.67–47.60 µIU/ml in the upright position), and aldosterone renin ratio (ARR) was 0.28. Urinary sodium output was also elevated (169 mEq/L). So unilateral renal artery stenosis (RAS) was suspected. To confirm RAS, abdominal doppler and pelvic CT investigations were requested. The CT and Doppler report was normal, excluding the diagnosis of renal artery stenosis.
Similarly, arterial blood gas (ABG) analysis was normal, which was against the metabolic alkalosis seen in Gitelman syndrome. To rule out an autoimmune cause, an antinuclear antibody (ANA) was sent; however, it also came out to be negative (Additional file 1).
The patient's clinical presentation, including severe abdominal pain, was not relieved even with morphine. After all these thorough investigations, severe uncorrected hyponatremia, severe body ache especially in the lower limbs, and precipitation of the symptoms following fasting ushered our conjectures toward the diagnosis of porphyria-related disorders. With the suspicion of porphyria, a urine sample was sent to Biochemistry Laboratory. Watson-Schwartz test was positive (Fig. 1); hence, it indicated the presence of porphobilinogen in urine substantiating the diagnosis of acute porphyria crisis. The urine color also darkened on exposure to light (Fig. 2). The symptoms were gradually relieved with the consumption of carbohydrate-rich foods. Genetic confirmation of HMBS mutation was not possible due to financial constraints. However, on the grounds of a strong clinical picture and screening for PBG in urine, a final diagnosis of acute intermittent porphyria was made.
She was kept on a high-sugar diet as hemin was unavailable. Gradually her pain subsided, her blood pressure came to normal and her bowel habit also improved. Pregabalin was given for neuropathic pain, which was gradually tapered and stopped during follow-up. The patient was counseled to avoid fasting. On follow-up examination in the outpatient department (OPD), she was asymptomatic with normal blood pressure and bowel habit.