Dimercaptosuccinic acid (succimer; DMSA) in inorganic lead poisoning

Therapeutic efficiency of succimer used with calcium and ascorbic acid in the treatment of mild lead-poisoning

The aim of this study was to explore therapeutic efficiency of succimer used with calcium and ascorbic acid in the treatment of mildly lead-poisoned mice and preschool children. Mice were exposed to lead by drinking water, and then treated with saline solution, 50mg/kg body weight (b.w.) succimer, 100mg/kg b.w. succimer, or 50mg/kg b.w. succimer plus calcium and ascorbic acid by gavage. Seventy-two children aged 48-72 months were randomly assigned into combined treatment or nutritional intervention group. Lead levels in blood and bone were analyzed by atomic absorption spectrophotometry. Activities of aminolevulinic acid dehydratase (ALAD) in blood were determined by colorimetric method. Results of animal experiment showed that succimer used alone could reduce lead levels in blood and bone and reverse activities of ALAD in blood, however, a better therapeutic efficiency in mobilizing bone lead could be achieved by succimer used with calcium and ascorbic acid. Findings from the clinical study showed that reduction of blood lead levels (BLLs) between the end and initiation of therapy in the combined treatment group was significantly greater than that in the nutritional intervention group. Percentage of children with BLLs less than 10μg/dL at the end of therapy and the eighth week after therapy in the combined treatment group was significantly higher than that in the nutritional intervention group. In conclusion, combined use of succimer with calcium and ascorbic acid seemed to be a choice in the treatment of mildly lead poisoned children.

Thrombocytosis secondary to chronic lead poisoning

We report a case of total hyperpigmentation of the skin, severe itching, muscle weakness and thrombocytosis. Laboratory investigation showed white blood cell (WBC) 8.2 x 10(6)/L, Hb 125 g/L, platelets 1221 x 10(6)/L and urinary lead after DMSA mobilization test 2684 mcg/g creatinine (normal <5). Chelation therapy with DMSA resulted in complete recovery of the hyperpigmentation, itching and thrombocytosis. Lead poisoning should be considered in the differential diagnosis of obscured thrombocytosis.

Metal Exposure in the Children of Punjab, India

Our test results documented that hair and urine mineral analysis results support each other. This is of interest, because hair analysis evaluates past exposure while urine analysis detects immediate exposure.

We evaluated barium, cadmium, manganese, lead and uranium in hair and urine. Our test results indicate that all of the children show evidence of past and immediate exposure to one or more metals.

Hair mineral test results for the 114 children aged 12 and younger showed some type of toxic metal exposure for each one of the children; 88% exceeded the uranium reference range for hair. This indicates past and chronic exposure.

After renal evaluation, 55 children aged 3–12 years who passed certain criteria were selected for urine baseline testing. Urine baseline concentrations are a direct reflection of immediate exposure. Of the 55 children, 47 showed elevated urine concentrations for one or more of the toxins listed above, demonstrating immediate exposure.

DMSA is recommended as an oral antidote for lead and other metals. We selected 55 children aged 3–12 for a DMSA (Dimercapto succinic acid) urine challenge test. Our results showed that 98% of this group showed lead concentrations above the baseline level, demonstrating lead binding and excretion. The DMSA challenge did not affect barium, cadmium, manganese and uranium, suggesting that for these elements, DMSA may not be the chelating agent of choice.

In summary, hair and urine mineral testing demonstrated that chronic and immediate toxic exposure had affected our test group of Punjabi children. The DMSA challenge test was effective in detoxifying lead, but did not affect barium, cadmium, manganese or uranium.

Acute lead intoxication in a female battery worker: Diagnosis and management

Lead is a significant occupational and environmental hazard. Battery industry is one of the settings related to lead intoxication. Published information on the use of oral chelating agents for the treatment of anaemia in the context of acute lead intoxication is limited. The patient was a 33 year immigrant female worker in a battery manufacture for 3 months. She complained for malaise that has been developed over the past two weeks. Pallor of skin and conjunctiva was the only sign found in physical examination. The blood test on admission revealed normochromic anaemia. Endoscopic investigation of the gastrointestinal system was negative for bleeding. The bone marrow biopsy was unrevealing.At baseline no attention has been paid to patient's occupational history. Afterwards the patient's occupational history has been re-evaluated and she has been screened for lead intoxication. The increased levels of the lead related biomarkers of exposure and effect confirmed the diagnosis. The patient received an oral chelating agent and an improvement in clinical picture, and levels of haematological and lead related biochemical parameters have been recorded. No side effect and no rebound effect were observed. This case report emphasizes the importance of the occupational history in the context of the differential diagnosis. Moreover, this report indicates that lead remains a significant occupational hazard especially in the small scale battery industry.

Chemical and biological properties of toxic metals and use of chelating agents for the pharmacological treatment of metal poisoning

Exposure to toxic metals is a well-known problem in industrialized countries. Metals interfere with a number of physiological processes, including central nervous system (CNS), haematopoietic, hepatic and renal functions. In the evaluation of the toxicity of a particular metal it is crucial to consider many parameters: chemical forms (elemental, organic or inorganic), binding capability, presence of specific proteins that selectively bind metals, etc. Medical treatment of acute and chronic metal toxicity is provided by chelating agents, namely organic compounds capable of interacting with metal ions to form structures called chelates. The present review attempts to provide updated information about the mechanisms, the cellular targets and the effects of toxic metals.