Anaemia and unexplained abdominal pain: looking for a lead

A 37 year old man, originally from India, presented with a five month history of worsening colicky abdominal pain, associated with nausea and vomiting. He had also been experiencing irritability, mood swings, and sleep disturbance over the past three months and erectile dysfunction for two months. Clinical examination showed mildly reduced power in both legs, with absence of the left knee jerk, while the right one could be elicited only after reinforcement. He had a normochromic normocytic anaemia with a haemoglobin of 96 g/L (reference range 130-170). The rest of his full blood count was normal. Iron studies, vitamin B₁₂, and folate were all within normal ranges, and there was no evidence of haemolysis. His peripheral blood morphology showed mild basophilic stippling but was otherwise unremarkable. He had been diagnosed as having type 2 diabetes six months previously, for which he was taking traditional (ayuverdic) remedies that had been sent from India. He underwent extensive investigations, including computed tomography of his abdomen and pelvis as well as upper and lower gastrointestinal endoscopy, all of which failed to identify a cause for his abdominal symptoms. A porphyria screen showed a urine 5-aminolevulinic acid (5-ALA) of 24.2 μmol/mmol (<3.8) with normal urine porphobilinogen. Urine coproporphyrin III and eythrocyte zinc protoporphyrin were subsequently found to be markedly raised.