Heme Synthesis and Porphyrias

A 7-year-old boy from an industrial area presents with irritability, vomiting, and abdominal colic. Examination reveals microcytic hypochromic anemia, basophilic stippling on blood smear, and Burton lines on the gingiva. Serum lead level is 65 µg/dL. The enzyme marked **A** in the heme synthesis pathway diagram is inhibited, along with ferrochelatase, leading to accumulation of ALA and zinc protoporphyrin. Which of the following is the most appropriate chelating agent for this child?

Which porphyria results from deficiency of porphobilinogen deaminase and presents with acute neurovisceral symptoms triggered by drugs or fasting?

A 28-year-old woman presents to the emergency department with acute severe abdominal pain, tachycardia (HR 110/min), and confusion. She has a history of similar episodes triggered by fasting and certain medications. Physical examination reveals dark urine and hypertension (BP 160/95 mmHg). Serum electrolytes show hyponatremia (Na⁺ 128 mEq/L) and hypokalaemia (K⁺ 3.2 mEq/L). Urine porphobilinogen (PBG) is markedly elevated. What is the most likely diagnosis?

A 35-year-old man with known porphyria cutanea tarda (PCT) presents with blistering lesions on sun-exposed areas and hepatomegaly. Laboratory work shows elevated liver enzymes and low serum ceruloplasmin. Which investigation is most specific for confirming the diagnosis of PCT and determining its type?

A 28-year-old woman from rural Maharashtra presents with acute onset severe abdominal pain, tachycardia, and confusion following exposure to sulfonamide antibiotics. She has a family history of recurrent neuropsychiatric episodes. Clinical suspicion is high for acute intermittent porphyria (AIP). Which investigation is most appropriate to confirm the diagnosis during the acute attack?