Review Question - QID 216351

This patient's clinical presentation (tachycardia, hypotension, dry mucous membranes) and abnormal labs (elevated BUN and serum creatinine, BUN/creatinine ratio >20) are indicative of prerenal acute kidney injury (AKI) secondary to recent gastrointestinal illness (vomiting, diarrhea). His concomitant herpes simplex exacerbation (given his oral vesicles) treatment (acyclovir) should only be addressed after correcting his renal function with IV fluids.

Acyclovir is used to treat herpes simplex virus (HSV) exacerbations. Although acyclovir is generally well tolerated, it is rapidly excreted in the urine and relatively insoluble; thus it can lead to crystal-induced nephropathy and acute renal failure. Significant volume contraction is the most important risk factor for the development of acute renal failure with acyclovir. Intrarenal acyclovir deposition can be prevented by avoiding rapid IV boluses of acyclovir and establishing euvolemia prior to beginning therapy. Patients with kidney dysfunction should be carefully monitored if started on acyclovir and instructed to stay hydrated in order to maintain renal function.

Perazella discusses crystal-induced acute renal failure and its notable precipitants in his review article on medications implicated in crystal-induced acute renal failure. He recommends monitoring kidney function when starting acyclovir.

Figure/Illustration A is a clinical photograph demonstrating herpes labialis which is caused predominantly by infection with HSV1. The classic finding of grouped vesicles evolving into crusted erosions on mucocutaneous surfaces is seen (black arrows).

Incorrect Answers:
Answer 1: Administering acyclovir before initiating IV fluids is incorrect because this patient's abnormal labs (elevated BUN, serum creatinine, and BUN/creatinine ratio >20) are indicative of a prerenal AKI which must be addressed prior to beginning acyclovir therapy. IV fluids should be administered to hypovolemic patients prior to initiating acyclovir therapy to avoid crystal-induced nephropathy and acute renal failure.

Answer 2: Prescribing oral foscarnet and following up outpatient is incorrect. This patient's abnormal labs (elevated BUN, serum creatinine, and BUN/creatinine ratio >20) are indicative of prerenal AKI which must be addressed prior to beginning antiviral therapy. Additionally, acyclovir is the preferred antiviral treatment for herpes simplex, whereas foscarnet is used for cytomegalovirus or acyclovir-resistant HSV.

Answer 4: Screening for tissue transglutaminase IgA antibodies is appropriate workup for celiac disease and possibly for dermatitis herpetiformis. Celiac disease typically presents with chronic diarrhea, malabsorption, and abdominal distention when consuming gluten. Dermatitis herpetiformis is a chronic and intensely pruritic eruption of vesicles, papules, and urticarial plaques on the extremities and trunk. Treatment typically requires a gluten-free diet.

Answer 5: Administering the recombinant zoster vaccine is incorrect because it will not improve this patient's HSV exacerbation. The recombinant zoster vaccine prevents herpes zoster, a reactivation of the varicella zoster virus which classically presents as a vesicular eruption limited to a dermatome. Patients often experience pruritus and neuropathic pain.

Bullet Summary:
IV fluids should be administered to hypovolemic patients with renal dysfunction prior to initiating acyclovir therapy to avoid crystal-induced nephropathy and acute renal failure.