[Marked improvement in renal tubular markers after switching from adefovir to tenofovir alafenamide in a case of Fanconi syndrome diagnosed through high ALP levels].

A woman in her 60s visited our hospital due to elevation of ALP (1357U/L). The patient had been treated with lamivudine (LAM) in 2005, LAM+adefovir (ADV) in 2009, and ADV+entecavir in 2015 for chronic hepatitis B (CH-B). The ALP isozyme was predominantly bone type. Urinary ß-2 microglobulin (MG) and α-1MG increased to 49635µg/L and 64.1mg/L, respectively. Though no fractures were found during bone scintigraphy, the patient was diagnosed with Fanconi syndrome. However, 3 months after switching from ADV to tenofovir alafenamide (TAF), ALP decreased to 856U/L, and urinary ß-2MG and α-1MG decreased to 624µg/L and 6.0mg/L, respectively. Fanconi syndrome should be considered when an increase in ALP is observed in patients treated with ADV, and urinary ß-2MG and α-1MG assays are useful for establishing a diagnosis. Switching from ADV to TAF was an effective therapeutic option.