Lead poisoning natural history, complications and prognosis

If left untreated, 100% of patients with [lead poisoning] may progress to develop seizures, unconsciousness and death.

• Symptoms of acute lead poisoning usually develop in the first 3 year of life, and start with symptoms such as pain, muscle weakness, numbness and tingling, and, rarely, symptoms associated with encephalitis.^[1] Abdominal pain, nausea, vomiting, diarrhea, and constipation are other acute symptoms.^[2] Lead’s effects on the mouth include astringency and a metallic taste.^[2] Gastrointestinal problems, such as constipation, diarrhea, poor appetite, or weight loss, are common in acute poisoning. Absorption of large amounts of lead over a short time can cause circulatoryshock due to loss of water from the gastrointestinal tract.^[2] Hemolysis due to acute poisoning can cause anemia and hemoglobinuria.^[2] Damage to kidneys can cause changes in urination such as oliguria.^[2]

• Common complications of lead poisoning include:
  • gastrointestinal
  • neuromuscular
  • neurological

Central nervous system and neuromuscular symptoms usually result from intense exposure, while gastrointestinal symptoms usually result from exposure over longer periods.^[2] Signs of chronic exposure include loss of short-term memory or concentration, depression, nausea], abdominal pain, loss of coordination, and numbness and tingling in the extremities.^[3] Fatigue, problems with sleep, headaches, stupor, slurred speech, and anemia are also found in chronic lead poisoning.^[1] A “lead hue” of the skin with pallor and/or lividity is another feature of chronic lead poisoning.^[4][5] A blue line along the gum with bluish black edging to the teeth, known as a Burton line, is another indication of chronic lead poisoning.^[6] Children with chronic poisoning may refuse to play or may have hyperkinetic or aggressive behavior disorders.^[1] Visual disturbance may present with gradually progressing blurred vision as a result of central scotoma, caused by toxic optic neuritis.^[7]

• Studies conducted in the recent past have confirmed that long term exposure of low levels of lead, which were previously determined to be safe are a major risk factor for atherosclerotic cardiovascular disease in adults and cognitive deficits in children. The effects of exposure to lead on long term basis varies in children and adults.

Complications

• Low level lead poisoning in children was found to be a risk factor for :
  • Preterm Labor
  • Cognitive defects
  • Attention Deficit Hyperkinetic Disorder(ADHD)
  • Elevated Blood Pressure
  • Reduced Heart rate variability.
• In adults it is associated with :
  • CKD
  • Hypertension

• Lead exposure is found to be a risk factor for preterm birth ,a 10 microgram elevation in blood lead levels is associated with 70 % increase in preterm birth.For those with Vitamin D deficiency this risk is even more elevated.
• Lead exposure is associated with reduced I.Q ,with higher reductions occurring at relatively low levels of exposure.^[8]
• Childhood exposure to Lead is a known risk factor for anti social disorders ,including
  • Conduct disorder
  • Delinquent behaviour
  • Criminal behaviour.

• • In Adults:
• Higher blood or bone levels are found to be congruently associated with accelerated cognitive decline; especially in those withAPOE4 alleles, drawing suspicion that it may have a role as a risk factor for late onset Alzheimer’s disease.

• Lead causes cellular changes that are characteristic for hypertension and atherosclerosis.Is is a leading risk factor for death from cardiovascular disease. *Laboratory studies revealed endothelial cells incubated in lead for 72 hours at concentrations of 0.14 to 8.2 μg per liter showed signs of membrane damage , which is the earliest finding in the natural history of atherosclerosis.
• Studies revealed that the risk of death from cardiovascular disease and coronary artery disease increased sharply at levels below 50 μg per liter, when adjusted for other risk factors.

• The incidence of hypertension in the U.S decreased tremendously during the phaseout of leaded gasoline.
• The usual factors like smoking, antihypertensive medicines, obesity, or even the larger size of the cuff used to measure blood pressure in persons with obesity — did not explain the decline.but it was observed that the median blood lead levels dropped by 100 μg per litre over a period of 18 years, which point towards the role of Lead in the causation of hypertension^[9]

• Lead causes cellular changes that are characteristic for hypertension and atherosclerosis.Is is a leading risk factor for death from cardiovascular disease. *Laboratory studies revealed endothelial cells incubated in lead for 72 hours at concentrations of 0.14 to 8.2 μg per liter showed signs of membrane damage , which is the earliest finding in the natural history of atherosclerosis.
• Studies revealed that the risk of death from cardiovascular disease and coronary artery disease increased sharply at levels below 50 μg per liter, when adjusted for other risk factors.

• The incidence of hypertension in the U.S decreased tremendously during the phaseout of leaded gasoline.
• The usual factors like smoking, antihypertensive medicines, obesity, or even the larger size of the cuff used to measure blood pressure in persons with obesity — did not explain the decline.but it was observed that the median blood lead levels dropped by 100 μg per litre over a period of 18 years, which point towards the role of Lead in the causation of hypertension^[9]

• Prognosis is generally related to the extent and duration of lead exposure.^[10]

Effects of lead on the physiology of the kidneys and blood are generally reversible; its effects on the central nervous system are not.^[11] While peripheral effects in adults often go away when lead exposure ceases, evidence suggests that most of lead’s effects on a child’s central nervous system are irreversible.^[12] Children with lead poisoning may thus have adverse health, cognitive, and behavioral effects that follow them into adulthood.^[13]

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