Proximal Renal Tubular Acidosis and Fanconi Syndrome Associated with Tenofovir Disopyroxil Fumarat: The Importance of Arterial Blood Gas Analysis in Differrential Diagnosis of Severe Hypokalemia

Abstract

Proximal renal tubular acidosis (pRTA) may occur alone or with Fanconi syndrome and may be idiopathic or associated with many drugs and diseases. A 71-year-old female patient was admitted with persistent, symptomatic hypokalemia, who used tenofovir disoproxil fumarate (TDF) for chronic HBV infection. While the diagnosis could not be reached by venous blood gas analysis, arterial blood gas analysis showed isolated normal anion gap hypokalemic hyperchloremic metabolic acidosis, and hypomagnesemia, hypouricemia, and hypophosphatemia were detected in biochemistry, suggesting pRTA and Fanconi syndrome. Since other etiologic causes were excluded and the history was compatible, this was attributed to the use of TDF, and clinical and laboratory response was achieved when TDF was switched into tenofovir alfenamide (TAF). TDF-associated pRTA and Fanconi syndrome may occur independently from the duration of TDF use, and switching into TAF may control this complication without disrupting the treatment of HBV infection. Confirmation with arterial blood gas might be used in the differential diagnosis of electrolyte disorders such as hypokalemia, hypomagnesemia and hypophosphatemia, mixed acid-base disorders, especially in case of unexplained etiology or inconsistency of venous blood gase analysis and clinical picture and acid-base disorders and differences in anion gap that may be missed with venous blood gas analysis alone are detected.

Keywords

• Tenofovir Disopyroxil Fumarat
• hypokalemia
• Fanconi syndrome
• proximal renal tubular acidosis

Project Number

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Tenofovir Disopiroksil Fumarata Sekonder Proksimal Renal Tübüler Asidoz ve Fanconi Sendromu: Derin Hipokalemi Ayırıcı Tanısında Arter Kan Gazı ile Değerlendirmenin Önemi

Abstract

Proksimal renal tübüler asidoz (pRTA) tek başına ya da Fanconi sendromu ile birlikte ortaya çıkabilir. İdiyopatik olabileceği gibi birçok ilaç ve hastalıkla da ilişkisi bildirilmiştir. 71 yaşında, kronik HBV enfeksiyonu nedeniyle tenofovir disoproksil fumarat (TDF) kullanımı olan kadın hasta, dirençli, semptomatik hipokalemi ile başvurdu. Venöz kan gazı analizi ile tanıya ulaşılamazken arter kan gazında görülen izole anyon açığı normal hipokalemik hiperkloremik metabolik asidoz ve biyokimyada hipomagnezemi, hipoürisemi, hipofosfatemi saptanması üzerine pRTA ve Fanconi sendromu düşünüldü. Diğer etiyolojik nedenlerin dışlanması ve öykünün uyumlu olması nedeniyle bu durum TDF kullanımına bağlandı ve TDF kesilerek tenofovir alfenamide (TAF) geçildiğinde klinik ve laboratuvar tam yanıt elde edildi. TDF ilişkili pRTA ve Fanconi sendromu ilacın kullanım süresinden bağımsız olarak ortaya çıkabilir ve TAF’a geçiş HBV enfeksiyonu tedavisini aksatmadan komplikasyonu ortadan kaldırabilir. Hipokalemi, hipomagnezemi ve hipofosfatemi gibi elektrolit bozuklukları, mikst asid baz bozukluğu olan ve etiyolojinin açıklanamadığı ya da klinik tablo ile uyumsuz venöz kan gazı analizi sonuçları elde edildiğinde, gözden kaçabilecek asid-baz bozuklukları ve anyon açıklığındaki farkları saptamak için arter kan gazı ile doğrulama ayırıcı tanıda yararlı olabilir.

Keywords

• Tenofovir Disopiroksil Fumarat
• hipokalemi
• Fanconi sendromu
• proksimal renal tubuler asidoz

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