Lead poisoning

INTRODUCTION:
  • Populations are exposed to lead chiefly via paints, cans, plumbing fixtures and leaded gasoline.
  • International lead poisoning prevention week is celebrated in October
  • The pathogenesis hypochromic anemia in lead poisoning is due to Inhibition of enzymes involved in heme biosynthesis
  • The intensity of these exposures remains high because of the deterioration of lead paint used into the past and the entrainment of lead from the paint and vehicle exhaust into soil and household. Greatest source of environmental (non-occupational) is gasoline
  • Most common mode of absorption in case of occupational lead poisoning is inhalation of flumes and dust of lead and its compounds. 
CLINICAL FINDINGS:
  • The clinical findings of lead poisoning are different in the inorganic and organic lead exposures. 
  • Inorganic lead poisoning: Aabdominal colic, constipation, loss of appetite, blue line on the gums, stippling of red cells, anemia, wrist drop and foot drop.
  • Organic lead poisoning: The toxic effects of organic lead poisoning are mostly on the CNS causing insomnia, headache, mental confusion, delirium, etc.
  • Characteristic features of chronic lead poisoning includes:
  1. Facial pallor: Particularly of the mouth is the earliest and most consistent sign.
  2. Anemia: Anemia associated with polychromasia, punctate basophilia, reticulocytosis, poikolocytosis, anisocytosis and sideroblastosis. Basophilic stippling refers to the presence of dark blue pin head sized spots in the cytoplasm of red blood cells.
  3. Saturnism = Saturnine poisoning- ALA in urine, Coproporphyrin in urine, facial pallor, Basophilic stippling/Punctate basophilia (dark blue, pin-head spots in cytoplasm of RBCs), Burtonian line (blue line gums' margin, PbS, 50-70% cases, near carious/dirty teeth, Lead palsy, Pb encephalopathy, wrist drop, foot drop, Colic, Constipation, Menstrual irregularity, Sterility, Nephropathy, X-ray- radio-opaque bands at metaphyses of long bones, Pb >0.03mg% in blood is diagnosticLead line or Burtonian line: seen on gums in 70% cases.
  4. Colic and constipation seen in 85% cases.
  5. Lead palsy: Radial nerve is most commonly involved resuling in wrist drop. 
  6. Encephalopathy: It is seen in every case of plumbism. Lead encephalopathy is irreversible and 85% have permanent brain damage.
INVESTIGATIONS:
  • Epiphyseal plate 'lead lines' on long bone X-rays.
  • Normocytic, normochromic anemia
  • Coproporphyrin in urine (CPU)
  • Amino levulinic acid in urine (ALAU)
  • Lead in blood and urine
  • Protoporphyrin levels >100 μg/dl 
Exam Question of:
  • Saturnism’ is seen in Chronic lead poisoning
  • Facial pallor is the earliest sign of lead poisoning
  • Lead poisoning shows abdominal colic, constipation, weakness of hand and anemia
  • Inhalation is the most common mode of lead poisoning
  • International lead poisoning prevention week is celebrated in October
  • Protoporphyrin levels >100 μg/dl indicates Lead poisoning
  • Sideroblastic anemia is caused by Lead poisoning
  • The pathogenesis hypochromic anemia in lead poisoning is due to Inhibition of enzymes involved in heme biosynthesis
  • Plumbism is caused by Lead poisoning
  • Anaemia, punctate basophilia, constipation blue line and abdominal colic are characreristic of Lead poisoning
  • Least common complication of lead poisoning in adults Peripheral neuropathy
  • Coproporphyrin is excreted typically in lead poisoning
  • In case of chronic lead poisoning, the levels of 6-amino levulinic acid

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