Chronic Mercury Toxicity Associated With Habitual Dried Shark Consumption in Oman: A Case Report

Mercury exposure is closely linked to the consumption of contaminated fish, particularly those containing methylmercury. Mercury toxicity presents with a wide range of nonspecific symptoms, making diagnosis challenging for clinicians. The clinical manifestations vary depending on the type of mercury, levels and duration of exposure, and individual susceptibility. We report a case of a 69-year-old woman with no significant past medical history who presented to the Emergency Department (ED) with chronic abdominal pain, muscle aches, bloating, and generalized fatigue lasting over a year. An initial evaluation in Thailand revealed an elevated blood mercury level of 38.72 μg/L during evaluation in Thailand. She was offered chelation therapy but declined and sought a second opinion in Oman. Repeated testing at the Central Public Health Laboratories two months later showed a mercury level of 24.36 μg/L (reference range <15 μg/L). Her complete blood count, renal function, and liver function tests were within normal limits. Dietary history revealed daily consumption of seafood and dried fish, including shark, as her primary protein source. Following cessation of dried fish consumption and reduction of seafood intake, blood mercury levels normalized without chelation therapy. Seafood, particularly dried fish, can be a significant source of methylmercury exposure. This case emphasizes the importance of obtaining a detailed dietary history when evaluating patients with chronic, nonspecific symptoms. Identifying dried fish as a key source of mercury exposure in Oman highlights the need for public awareness and early recognition of environmental toxic exposures.