Concentration-related mydriasis in a patient with renal dysfunction treated with phenytoin.

INTRODUCTION: There is very limited evidence concerning phenytoin-related mydriasis. CASE REPORT: A 59-year-old male was hospitalized in the intensive care unit due to a head injury. During his hospitalization, phenytoin was administrated. Some days later he presented bilateral mydriasis.  At that time he had impaired creatinine clearance 7 ml/min, albumin levels 3.4 gr/dl, and phenytoin serum concentration 19.94 μg/dl. Evaluation with brain computed tomography and magnetic resonance imaging did not reveal any potential cause of mydriasis, while none of the co-administrated drugs have been reported to cause significant mydriasis. After initiation of continuous venovenous hemodiafiltration and discontinuation of phenytoin, mydriasis was reversed.
CONCLUSION: Clinicians should be aware that mydriasis due to a toxic concentration of phenytoin may be manifested. Hippokratia 2016, 20(2): 166-168.