Mercury poisoning: a rare but treatable cause of failure to thrive and developmental regression in an infant

An infant presented with failure to thrive and developmental regression. Physical examination revealed an irritable child with swollen, erythematous extremities, and elevated blood pressure. Extensive investigations, including a metabolic work-up and neuroimaging, were unrevealing. Exposure to self-purchased medication was initially denied. The physical signs were suggestive of acrodynia. Mercury poisoning was ultimately established by measuring paired blood and urine mercury levels. On further enquiry, it was revealed that the child had been given a Chinese medicinal product for 4 months. He responded well to a chelating agent. Acrodynia is a childhood disease considered to be of historical interest only, but making a diagnosis of mercury poisoning is rewarding because the response to treatment is good. This case highlights the common misconception that alternative medicines are safe and benign.

A Child with Elemental Mercury Poisoning and Unusual Brain MRI Findings

Mercury vapor poisoning is a serious and potentially fatal problem. Neurological manifestations involving the central nervous system are seen with chronic mercury intoxication. We present the case of a 10-year-old child who demonstrated acrodynia, seizures, and visual impairment following 20 days of exposure to elemental mercury at home. The initial blood mercury concentration was 27.7 microg/L (normal <2 microg/L) and the initial 24-hour urine mercury concentration was 34.4 microg/L (normal =10 microg/L). After 9 months of treatment with D-penicillamine, the patient's clinical condition, biochemical laboratory parameters, and mercury concentrations all returned to normal. The T2-weighted MRI images of the patient's brain initially showed multiple hyperintense lesions in cerebral white matter, left globus pallidus, and putamen, which also improved.

Mercury intoxication in a 2-year-old girl: a diagnostic challenge for the physician

A 2-year-old girl presented with hypertension, anorexia and vomiting, restlessness, insomnia and acrodynia. Her blood pressure upon arrival was 145/98 mmHg. Ultrasound of the abdomen, CT scan of chest, abdomen and pelvis, and echocardiogram, were normal. Urinary levels of catecholamines were elevated, urine level of mercury was found to be high (33.2 microg/g creatinine), although blood level was normal (>0.5 microg/dl, reference value 0-4 microg/dl). Following a 1-month course of oral treatment with dimercaptosuccinic acid (DMSA) the child's symptoms and signs resolved, and urinary mercury and catecholamines levels normalized. Mercury intoxication should be suspected in a patient with severe hypertension, personality changes and acrodynia. Normal blood levels of mercury do not exclude this diagnosis, and catecholamine levels may serve as a surrogate marker for confirmation of the diagnosis and to evaluate response to treatment.

Mercury intoxication: it still exists

A3-year-old boy presented to the Hospital for Sick Children with systemic symptoms and oropharyngeal and peripheral extremity changes suggestive of Kawasaki disease. He was found to have severe hypertension. Investigation for a catecholamine-secreting tumor was negative. Toxins were considered when the patient's 20-month-old brother presented with similar symptoms, and the boys were subsequently diagnosed with elemental mercury poisoning. We review the literature on mercury intoxication and discuss the historical context, clinical syndrome (acrodynia), treatment, and radiologic findings of this unusual diagnosis.

Mercury exposure and early effects: an overview

OBJECTIVES

This paper was given as a keynote address at the conference on The Assessment of the Effects Due to Low Doses of Inorganic Mercury following Environmental and Occupational Exposures: Human and in vitro Studies on the Specific Mechanisms of Toxicity in Gargnano, Italy, in September 2001.

METHODS

The most relevant literature over the past 40 years has been reviewed, and in particular, the proceedings of the World Health Organisation conferences on the health effects of inorganic and organic mercury exposure have been considered.

RESULTS

In an uncontaminated environment the general population is exposed to mercury vapour from the atmosphere and from dental amalgam, while the diet, mainly from fish, is the principal source for methyl mercury absorption. Mercury vapour release from amalgam fillings increases with chewing, with absorption and uptake by the brain and kidneys. Infants exposed to phenyl mercury from treated diapers and young children ingesting mercurous chloride in teething powders have developed acrodynia (pink disease), and Kawasaki disease and the use of mercurial skin lightening creams has been followed by the development of the nephrotic syndrome. Both mercury compounds and mercury vapour have given rise to contact dermatitis in the general population. Epidemics of mercury poisoning have followed release of mercury into the environment from industrial activity, with uptake of methyl mercury from fish eating in Minamata Bay and uptake of both inorganic and methyl mercury following release of mercury vapour and deposition into waterways from gold recovery procedures in the Amazon basin. The ingestion of wheat and barley seed treated with an alkyl mercury fungicide for sowing, by a largely illiterate population in Iraq, led to a major outbreak of poisoning with a high fatality rate. Following exposure to mercury vapour, the earliest clinically observed adverse effects at urine mercury levels of the order of 30-100 mg/g creatinine, are objectively detectable tremor, psychological disorder and impaired nerve conduction velocity in sensitive subjects, with subjective symptoms of irritability, fatigue and anorexia. At these and at lower levels, proteinuria has also been observed. Both glomerular and tubular damage may occur at exposure levels lower than those giving rise to central nervous system effects. An immunological effect has also been observed in studies on clinically asymptomatic workers with low level exposure.

CONCLUSIONS

As mercury can give rise to allergic and immunotoxic reactions which may be genetically regulated, in the absence of adequate dose-response studies for immunologically sensitive individuals, it has not been possible to set a level for mercury in blood or urine below which mercury related symptoms will not occur.

Mercury exposure and cutaneous disease

Human contact with mercury has been ongoing for centuries and was previously considered a legitimate means of treating different cutaneous and systemic conditions. Toxicity from this heavy metal may occur from exposure to elemental, inorganic, and organic forms of mercury. This article outlines the signs and symptoms of mercury poisoning and the different clinical conditions with assorted cutaneous findings.

Pyridoxine deficiency and antagonism produce increased ground substance viscosity with resulting seborrheic dermatitis and increased tumor resistance

Pyridoxine deficiency and 4'-deoxypyridoxine produce acrodynia in rats and seborrheic dermatitis in man. They also produce tumor inhibition in man and animals. Pyridoxine is extensively involved in metabolism and its relationship to the inhibitor 4'-deoxypyridoxine is complex. Pyridoxine deficiency and antagonism increases ground substance viscosity. This increase the inflammatory reactivity of the skin to produce acrodynia in rats and seborrheic dermatitis in man. The increase in ground substance viscosity would explain the increased resistance to tumors in man and animals. Pyridoxine is important in protein metabolism. The protein moiety of glycosaminoglycans in ground substance is small but plays a major role in tissue viscosity. Pyridoxine deficiency or antagonism by itself does not offer a definitive answer for tumors. Combined with substances that stimulate fibroblast or glycosaminoglycans production it may have a significant additive effect.

A case of mercury poisoning: acrodynia in a child of 8

Images