G. Novljan
Klinični oddelek za nefrologijo, Pediatrična klinika, Univerzitetni klinični center Ljubljana, Ljubljana, Slovenija
N. Battelino
Klinični oddelek za otroško nefrologijo, Pediatrična klinika, Univerzitetni klinični center Ljubljana, Ljubljana, Slovenija
M. Kopač
Klinični oddelek za nefrologijo, Pediatrična klinika, Univerzitetni Klinični center Ljubljana, Ljubljana, Slovenija
A. Meglič
Klinični oddelek za nefrologijo, Pediatrična klinika, Univerzitetni Klinični center Ljubljana, Ljubljana, Slovenija
R. Rus
Klinični oddelek za nefrologijo, Pediatrična klinika, Univerzitetni Klinični center Ljubljana, Ljubljana, Slovenija
T. Kersnik Levart
Klinični oddelek za nefrologijo, Pediatrična klinika, Univerzitetni klinični center Ljubljana, Ljubljana, Slovenija
Abstract
Proteinuria is an important early marker of kidney disease and is associated with progressive deterioration of kidney function, leading to end-stage renal disease. The normal rate of urinary protein excretion in a healthy child is less than 100 mg/m2 per day (≈ 150 mg/day). The mechanisms of proteinuria can be categorized as glomerular, tubular, or overflow. Proteinuria can also be due to mixed causality, with the prevalence of one or two type. The most frequently used screening method for proteinuria is the urinary dipstick. Urinary protein excretion can be measured quantitatively in 24-hour urine collections, or, the protein/creatinine ratio (U-P/C) of a single-void urine specimen can be used. Once proteinuria has been confirmed, the type of excreted proteins can be determined, in order to define the aetiology of the proteinuria. As a rule, a fresh sample of urine is examined, which has to be obtained according to established guidelines. Most guidelines recommend a spot first-morning urine specimen for proteinuria assessment. However, considerable disagreement exists regarding this matter. There are numerous causes of proteinuria. It is important to determine whether proteinuria is incidental, transient, orthostatic or persistent. Most children with asymptomatic proteinuria, diagnosed at screening urinalysis, do not have kidney disease. If proteinuria exists with active urinary sediments, haematuria, hyperten sion and renal insufficiency with depressed glomerular filtration rate, serious renal disease may be present. Clinical features from the history and physical examination help determine the cause of proteinuria. A child with persistent proteinuria should be referred to a paediatric nephrologist for extended investigation, which, if clinically indicated, may include renal biopsy to obtain the diagnosis, and for the initiation of treat-ment when necessary.
Key words: proteinuria, children, chronic kidney disease.