Acrodynia

Acrodynia is a condition of pain and dusky pink discoloration in the hands and feet most often seen in children chronically exposed to heavy metals, especially mercury.

The word acrodynia is derived from the Greek, where ακρος means end or extremity and οδυνη means pain. As such, it might be (erroneously) used to indicate that a patient has pain in the hands or feet. However, acrodynia is a disease rather than a symptom.^[2] The condition is known by a large number of other names including pink disease, hydrargyria, mercurialism, erythredema, erythredema polyneuropathy, Bilderbeck's, Selter's, Swift's and Swift-Feer disease.

Symptoms

Besides peripheral neuropathy (presenting as paresthesia or itching, burning or pain) and discoloration, swelling (edema) and desquamation may occur.

Since mercury blocks the degradation pathway of catecholamines, epinephrine excess causes profuse sweating (diaphora), tachycardia, salivation and elevated blood pressure. Mercury is suggested to inactivate S-adenosyl-methionine, which is necessary for catecholamine catabolism by catechol-o-methyl transferase.

Affected children may show red cheeks and nose, red (erythematous) lips, loss of hair, teeth, and nails, transient rashes, hypotonia and photophobia. Other symptoms may include kidney dysfunction (e.g. Fanconi syndrome) or neuropsychiatric symptoms (emotional lability, memory impairment, insomnia).

Thus, the clinical presentation may resemble pheochromocytoma or Kawasaki disease.

There is some evidence that the same mercury poisoning may predispose to Young's syndrome (men with bronchiectasis and low sperm count).^[3]

Causes

Mercury compounds like calomel were historically used for various medical purposes: as laxatives, diuretics, antiseptics or antimicrobial drugs for syphilis, typhus and yellow fever^[4] . Teething powders were a widespread source of mercury poisoning until the recognition of mercury toxicity in the 1940s.

However, mercury poisoning and acrodynia still exist today.^[5] Modern sources of mercury intoxication include broken thermometers.^[6]

Therapy

The standard of care is discontinuation of the environmental exposure, and chelation therapy (with EDTA or maybe better, DMSA).

References