Transient proteinuria and acute kidney injury (AKI) are characteristics of Puumala virus (PUUV) infection. Albuminuria peaks around the fifth day and associates with AKI severity. To evaluate albuminuria disappearance rate, we quantified albumin excretion at different time points after the fever onset. The study included 141 consecutive patients hospitalized due to acute PUUV infection in Tampere University Hospital, Finland. Timed overnight albumin excretion (cU-Alb) was measured during the acute phase in 133 patients, once or twice during the convalescent phase within three months in 94 patients, and at six months in 36 patients. During hospitalization, 30% of the patients had moderately increased albuminuria (cU-Alb 20-200 μg/min), while 57% presented with severely increased albuminuria (cU-Alb >200 μg/min). Median cU-Alb was 311 μg/min (range 2.2-6460) ≤7 days after fever onset, 235 μg/min (range 6.8-5479) at 8-13 days and 2.8 μg/min (range 0.5-18.2) at 14-20 days. After that, only one of the measurements showed albuminuria (35.4 μg/min at day 44). At six months, the median cU-Alb was 2.0 μg/min (range 0.6-14.5). Albuminuria makes a flash-like appearance in PUUV infection and returns rapidly to normal levels within 2-3 weeks after fever onset. In the case of AKI, this is a unique phenomenon.
Keywords: HFRS; Puumala virus; acute kidney injury; albuminuria; hantavirus; hemorrhagic fever with renal syndrome; proteinuria.