Heavy metal - habitual licking of a lead tape as rare cause of chronic lead poisoning: a case report.

BACKGROUND: Lead poisoning remains a major environmental health risk for children, as no safe blood lead concentration has been identified and even low-level exposure can cause neurocognitive, behavioral, cardiovascular and renal impairments. Although blood lead levels have declined substantially in high-income countries due to regulatory measures such as the elimination of leaded gasoline and stricter environmental controls, lead exposure continues to pose a significant global public health burden, particularly in low- and middle-income countries. Moreover, uncommon exposure pathways still occur in industrialized nations, making the diagnosis challenging and underscoring the importance of considering environmental exposures in pediatric practice. CASE PRESENTATION: A 10-year-old boy presented with a two month history of colicky abdominal pain, constipation, postprandial vomiting, 7 kg weight loss, and general weakness. A diagnostic laparoscopy performed at an external hospital was unremarkable. He had undergone appendectomy two years earlier and had no prior health issues. During hospitalization he developed visual disturbances, headaches, and abdominal pain crises requiring opioid treatment. He exhibited psychotic behavior, but no evidence for somatization disorder was found. RESULTS: Laboratory tests revealed mildly elevated aminotransferases, hypochromic microcytic anemia and basophilic stippling on the blood smear. Abdominal x-ray and MRI were unremarkable. Urinary porphyria analysis confirmed elevated porphobilinogen (PBG) and delta-aminolaevulinic-acid (ALA), suggestive of ALA-dehydratase-deficiency (Doss-porphyria). Cranial MRI showed lesions compatible with posterior reversible encephalopathy syndrome (PRES), consistent with previously described porphyria-induced PRES. As differential diagnosis, lead intoxication was considered, as it inhibits ALA-dehydratase and raises ALA more than PBG. Surprisingly, blood lead levels were markedly elevated (581 µg/L ( ≤ 22 µg/L)). Chelation therapy with dimercaptopropanesulfonic acid was initiated, leading in symptom resolution within 48 h. As no source of lead exposure was initially identified and family members showed no elevated levels, ongoing exposure was suspected. After seven weeks, the boy's grandmother discovered the source: a damaged lead tape used as curtain weight, which the boy had been licking for months while gaming. Following removal of this tape, blood lead levels gradually declined. CONCLUSION: Lead intoxication should remain a differential diagnosis despite its decreasing incidence. Its clinical presentation can mimic porphyria, and lead-induced encephalopathy may resemble PRES.