SECONDARY FANCONI SYNDROME IN TUBULOINTERSTITIAL NEPHRITIS, SARS-COV-2-ASSOCIATED

Introduction:

We wanted to demonstrate 2 similar clinical observations with secondary Fanconi syndrome, which developed as a result of tubulointerstitial nephritis, most likely associated with SARS-COV-2.

Methods:

In 1st case, a 7 years old boy with no signs of growth retardation developed nausea and weight loss (24%), a 2-fold increase in creatinine (from 35 to 80 μmol/l) was detected 3 weeks after clinical symptoms, and after 6 months of observation, Fanconi syndrome was detected (polyuria, metabolic acidosis, LMW proteinuria, glucosuria, phosphaturia, hypokalemia, hypophosphatemia) with a decrease eGFR. In 2nd case, a 14 years old girl had nausea, weight loss (26%) with manifestations of Fanconi syndrome (proteinuria, glucosuria, metabolic acidosis) with acute renal injury (azotemia, anuria) after a respiratory disease for 1 month. The girl underwent 7 hemodialysis sessions with partial recovery of renal function. LMW proteinuria, glucosuria, decreased TmP/GFR and increased Fe Urea (23%) persisted at the time of hospitalization in the clinic.

Results:

In both children, hereditary causes (symptom onset at 7 years of age or older), drug exposure, and immunological diseases were excluded. The duration of the disease before renal biopsy was 12 months in 1st case and 6 months in the 2nd case. Kidney histology shows interstitial nephritis, with focal or diffuse lymphocytic infiltration. Both children had high levels IgG of SARS-COV-2, which may be the cause of interstitial nephritis. Both children received steroids and in 1st case with positive dynamics (disappearance of glucosuria, reduction of LMW proteinuria and increase eGFR  to 72 ml/min/1.73m2), but in the 2nd case, Fanconi syndrome persisted without dynamics of eGFR.

Conclusions:

Early diagnosis, degree of renal damage and early treatment can determine the prognosis of renal survival. In our demonstration, in case 2 the more unfavorable.

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.