174 CASE REPORT

Abstract

Objective: “Protein shakes” are commonly used as life style products, mostly in males engageing in bodybuilding activities. It has long been known that protein loads cause renal hyperfiltration. It is therefore conceivable that upon long-term use renal damage may be induced, particularly in persons with pre-existing renal dysfunction. Patient and Methods: A 48-year-old male was referred to our outpatient clinic for work-up of an elevated creatinine value of 2.49 mg/dl; one year before his creatinine was 1.49 mg/dl (normal range < 1.1 mg/dl). For years the patient had performed bodybuilding at a commercial fitness center (about 2 hrs every day) including daily intake of post-workout protein shakes. The patient appeared athletic and his blood pressure was 143/80 mm Hg; no peripheral edema was present. Renal ultrasound showed parapelvic calcifications with no pelvic obstruction. Urinalysis showed mild proteinuria but no hematuria. Renal biopsy revealed diffuse chronic sclerosing eosinophilic interstitial nephritis. Clinical course: During the next 3 months the creatinine value further increased to 4.45 mg/dl; therapy with oral prednisolone (0.5 mg/kg body weight) was begun and tapered over a period of 3 months. His blood pressure started to increase to values around 160/100 mm Hg and antihypertensive therapy with amlodipine (10 mg/day) was initiated. Upon immunosuppression the creatinine concentration continuously decreased to a nadir of 2.41 mg/dl after 4 months. However, thereafter the creatinine value started to rise again and now end-stage renal failure is in sight. Conclusion: Long-term ingestion of “protein drinks” may lead to progressive chronic interstitial nephritis.