Images of Memorable Cases: Case 47 This healthy 16-year-old boy complained that the hair on his scalp had suddenly begun to fall out. Two weeks earlier, he had experienced the abrupt onset of abdominal pain with vomiting, followed several days later by paresthesias in his feet and weakness in his legs. Diffuse alopecia was his only physical abnormality. 47. Acute thallium poisoning The patient ultimately admitted that shortly before his symptoms began, he had tried to commit suicide by swallowing thallium-laden rat poison. His markedly elevated serum and urine levels of thallium confirmed his story. Alopecia is the clinical hallmark of thallium intoxication and develops in virtually everyone who survives the acute insult. It usually appears between the first and third week of illness, characteristically affects the scalp, and commonly spares the face, axillae, and pubic area. Other manifestations are variable and nonspecific.