Transient Fanconi Syndrome in a Child with Acute COVID-19 Infection: Authors' Reply.

To the Editor: This is regarding the query [1] related to our article, “Transient Fanconi Syndrome in a child with acute COVID-19 infection” [2]. Our case presented with all clinical and biochemical features of proximal renal tubular acidosis. The literature reveals that similar presentations have been documented in adults [3], mostly transient in nature, depending on the extent of renal injury. We have not documented direct renal invasion by the virus due to lack of such diagnostic facilities, although studies done in China have revealed direct viral invasion and injury, which may clinically manifest as proximal renal tubular acidosis. Hyperviscosity can cause a decrease in renal function with decreased creatinine clearance and rise in serum creatinine level. The serum creatinine levels were normal in our patient. Polyuria, which we have documented in our case, is not one of the manifestations of hyperviscosity-mediated renal dysfunction. Furthermore, the child we have reported had a hemoglobin value of 11 g/dL, with a hematocrit of 32%, which is appropriate for age, and hence, could not have contributed to hyperviscosity leading to renal injury [4].