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Bromide-induced pseudohyperchloridemia
Correspondence Bromide-Induced Pseudohyperchloridemia To the Editor: We read with great interest the review article entitled “Use and Monitoring of Bromides in Epilepsy Treatment” by Ryan and Baumann [1]. In the patient on bromide therapy the authors pointed out the presence of pseudohyperchloridemia in measuring chlorides by automatic chemistry analyzers, which could not distinguish between halide ions (i.e., bromide ions, chloride ions, and xenon ions). Inversely, the pseudohyperchloridemia may be useful in detecting serum concentrations of bromide and early bromide toxicity. We were interested in the correlation between serum concentrations of bromide and chloride and measured the serum concentrations of bromide and chloride ions in 13 samples from seven patients on potassium bromide treatment [2]. The serum levels of chloride ions were measured by dry chemistry (VITROS Dry Chloride, Ortho-clinical Diagnostics, Raritan, NJ), and the levels of bromide ions were measured by a potentiometer using the bromide ion selective electrode (HORIBA 8005-06T, Horiba, Kyoto, Japan). The concentrations of chloride and bromide ions were well correlated in our thirteen samples (r ⫽ 0.723). From the results, we obtained the following conversion formula: bromide ion levels (g/mL) ⫽ ⫺1648.703 ⫹ 15.625 ⫻ chloride ion levels (mEq/L) This formula illustrates that the therapeutic range of serum concentration of bromide ions (from 500 to 1,000 g/mL) transforms the range from 137.5 to 169.5 mEq/L in chloride ion
levels. Also, the toxic level of bromide ion concentrations (over 1,500 g/mL) is calculated as 201.5 mEq/L in chloride ion concentrations. Our data of chloride ions were obtained by use of dry chemistry. Changes of the device for measuring chloride ions could introduce different results. Thus the conversion formula from chloride to bromide must be established in each laboratory. We propose that measuring serum levels of chloride ions can estimate the serum concentration of bromide ions. These results may be helpful for treatment of epilepsy with bromide in terms of therapeutic drug monitoring to prevent the adverse effects of bromide. Hironori Matsufuji, MD Takashi Hayashi, MD Miki Nishikawa, MD Tomomi Yoshitomi, MD Takashi Ichiyama, MD Susumu Furukawa, MD Department of Pediatrics Yamaguchi University School of Medicine Ube, Yamaguchi, Japan
References [1] Ryan M, Baumann RJ. Use and monitoring of bromides in epilepsy treatment. Pediatr Neurol 1999;21:523-8. [2] Matsufuji H, Nishikawa M, Yoshitomi T, et al. Usefulness of chloride serum concentrations in being treated with potassium bromide. No To Hattatsu 1999;31:465-6.
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levels. Also, the toxic level of bromide ion concentrations (over 1,500 g/mL) is calculated as 201.5 mEq/L in chloride ion concentrations. Our data of chloride ions were obtained by use of dry chemistry. Changes of the device for measuring chloride ions could introduce different results. Thus the conversion formula from chloride to bromide must be established in each laboratory. We propose that measuring serum levels of chloride ions can estimate the serum concentration of bromide ions. These results may be helpful for treatment of epilepsy with bromide in terms of therapeutic drug monitoring to prevent the adverse effects of bromide. Hironori Matsufuji, MD Takashi Hayashi, MD Miki Nishikawa, MD Tomomi Yoshitomi, MD Takashi Ichiyama, MD Susumu Furukawa, MD Department of Pediatrics Yamaguchi University School of Medicine Ube, Yamaguchi, Japan
References [1] Ryan M, Baumann RJ. Use and monitoring of bromides in epilepsy treatment. Pediatr Neurol 1999;21:523-8. [2] Matsufuji H, Nishikawa M, Yoshitomi T, et al. Usefulness of chloride serum concentrations in being treated with potassium bromide. No To Hattatsu 1999;31:465-6.
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