Case report
A 90-year-old woman on anticoagulation therapy with phenprocoumon was referred for suspicion of an acute cerebral disorder. She lives with her husband in an apartment and had been mentally healthy without known consumption of alcohol or drugs. On the day of admission, however, she newly experienced confusion, speech impairment and vomiting. The medical history was remarkable for arterial hypertension, diabetes mellitus, a brain stem infarction two years ago from which the patient had fully recovered, and pulmonary embolism. Clinical examination revealed a fluctuating moderate to severe dysarthria and an ataxia of upper and lower extremities reaching 4-5 points of the possible 42 points on the NIH Stroke Scale. Cerebral MRI revealed no abnormalities explaining the clinical picture. Laboratory studies disclosed an acute renal failure with metabolic acidosis. An ultrasonography of the kidneys was unremarkable. A generalized epileptic seizure with loss of stool and urine in the emergency department was interpreted in the context of metabolic acidosis, and bicarbonate infusions were administered. Third-party medical history revealed that four days before admission treatment with valacyclovir 1000 mg three times a day was started for suspicion of genital herpes infection. No crystals were found in urine analysis. A four hours hemodialysis using a high-flux filter and a high blood flow rate was performed and hemodialysis treatment was repeated on the following three days. Neurological disturbances considerably improved after the second dialysis and entirely reversed after the fourth dialysis. Two days after the fourth dialysis has been finished, results of acyclovir levels in serum became available and were consistent with the suspected valacyclovir intoxication (Figure 1).
Figure 1. The course of serum levels of acyclovir, urea and creatinine under hemodialysis therapy in a 90-year-old woman with acute renal failure and severe neurotoxicity due to valacyclovir.
Acute renal failure due to valacyclovir treatment is a rare condition and may arise from intratubular crystal precipitation and interstitial nephritis [1,2]. Because of this rarity, renal function is often not monitored in outpatients with healthy kidneys on valacyclovir therapy and renal insufficiency first get noticed in the setting of neurologic adverse events. High dose hemodialysis treatment in our elderly patient with until recently normal kidney function was applied in view of the severe neurological impairment and at only moderately elevated urea levels and was well tolerated. The first two hemodialysis treatments could reduce acyclovir serum levels by 79% and 80%, respectively, and were therefore highly effective to reverse severe neurotoxicity.
References
- Tucker WE Jr. (1982) Preclinical toxicology profile of acyclovir: an overview. Am J Med 73: 27-30. [Crossref]
- Rashed A, Azadeh B, Abu Romeh SH (1990) Acyclovir-induced acute tubulo-interstitial nephritis. Nephron 56: 436-438. [Crossref]
