chronic lead poisoning

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chronic lead poisoning

Poisoning caused by chronic ingestion or inhalation of lead, which damages the central and peripheral nervous systems, kidneys, the blood-forming organs, and the gastrointestinal tract. Early symptoms include loss of appetite, weight loss, anemia, vomiting, fatigue, weakness, headache, lead line on gums, apathy or irritability, and a metallic taste in the mouth. Later, symptoms of paralysis, sensory loss, lack of coordination, and vague pains develop. Laboratory diagnosis is made through evidence of anemia, blood lead level above 5 μg/dl, elevated free erythrocyte protoporphyrin (FEP), increased excretion of lead in urine, and characteristic x-ray changes in the ends of growing bones.


Exposure to lead should be eliminated and an adequate diet with added vitamins provided. Chelating agents such as dimercaprol, dimercaptosuccinic acid (succimer), or EDTA are given to reduce lead levels to normal.

Patient care

A history is obtained to determine whether the sources of lead ingestion or inhalation are caused by the environment, work, or folk remedies, and preparations are made for their removal. (In many states, removal of household lead must be done by state-licensed specialists, not homeowners. The CDC and local poison-control centers provide relevant information. A 1-cm square chip of lead-based paint may contain a thousand times the usual safe daily ingestion of lead.) A history is obtained of pica; recent behavioral changes, particularly, in children, a lack of interest in playing; and behavioral problems such as aggression and hyperirritability. The patient is assessed for developmental delays or loss of acquired skills, esp. speech. central nervous system signs indicative of lead toxicity may be irreversible. The younger child is assessed for at-risk characteristics such as the high level of oral activity in late infancy and toddlerhood; small stature, which enhances inhalation of contaminated dust and dirt in areas heavily contaminated with lead; and nutritional deficiencies of calcium, zinc, and iron, the single most important predisposing factor for increased lead absorption. Older children are assessed for gasoline sniffing, which is esp. prevalent among children in some cultures. The parent-child interaction is assessed for indications of inadequate child care, including poor hygienic practices, insufficient feeding to promote adequate nutrition, infrequent use of medical facilities, insufficient rest, less use of resources for child stimulation, less affection, and immature attitudes toward maintaining discipline. Prescribed chelating agents are administered to mobilize lead from the blood and soft tissues by enhancing its deposition in bones and its excretion in urine. A combination of drugs may result in fewer side effects and better removal of lead from the brain. If encephalopathy is present, fluid volume is restricted to prevent additional cerebral edema. Injections are administered intramuscularly, and injection sites are rotated for painful injections (which may include simultaneous procaine injection for local anesthesia). The child is allowed to express pain and anger, and physical and emotional comfort measures are provided to relieve related distress. If there is no encephalopathy, injections are administered intravenously, and hydration is maintained. The patient is evaluated for desired drug effects measured by blood levels and urinary excretion of lead and for signs of toxicity from the chelating agents. (Special blood collection and urine collection containers are necessary for some of the monitoring tests. The laboratory should be consulted before collection.) . Prescribed anticonvulsants are administered as necessary to control seizures (often severe and protracted), an antiemetic for nausea and vomiting, an antispasmodic for muscle cramps, and analgesics and muscle relaxants for muscle and joint pain. Serum electrolytes are monitored daily, and renal function is evaluated frequently. Whole bowel irrigation is used when lead is visible in the GI tract (or for episodes of acute lead ingestion). Adequate nutrition is provided, and nutritional deficiencies are corrected, by administering prescribed supplements (e.g., of iron). An active, active-assisted, or passive range-of-motion exercise program is established to maintain joint mobility and prevent muscle atrophy. Parents are taught and supported to prevent recurrence, and the public is educated about the dangers of lead ingestion, the importance of screening young (esp. preschool) children at risk, the signs and symptoms indicative of toxicity, and the need for treatment.

See also: poisoning
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