Re-recognition of age-dependent reference range for the serum creatinine level in teenagers - A case of slowly progressive tubulointerstitial nephritis which occurred in an adolescent

Abstract

For the first time, a 15-year-old boy was found to have a slight degree of proteinuria and microscopic he-maturia during annual school urinalysis screening. His kidney function had already severely deteriorated. A kidney biopsy revealed tubulointerstitial nephritis (TIN) with diffuse inflammatory cell infiltration. His medical records showed his serum creatinine level to be 0.98 mg/dL two years ago, which was abnormally high considering his age. Although the etiology of slowly progressive TIN was unclear, glucocorticoid and im-munosuppressant therapy improved his kidney function. This case report suggests that all doctors should recognize the reference range for the serum creatinine level in teenagers.