Introduction:

The morning urine sample assay may improve the study of tubular function in children and adolescents.

Objective:

Describe the tubulopathies diagnosed in children and adolescents after the trial of morning urine samples.

Methods:

A retrospective and analytical study was completed at the Renal Function´s Study Laboratory, in the Clinical Laboratory Service at "Juan Manuel Marquez" Teaching Pediatric Hospital, with 70 reports of tubular function made in morning urine samples of 56 testees (males: 50.0%; average age: 4.3 ± to 5.5 years; ages< 12 months: 41.1%) attended from 2015 to 2019 (both inclusive) containing glomerular filtration values, absolute and fractional urinary excretion of substances of interest, anionic gap, partial gas pressure, and titrable acidity, pH, density and osmolarity of relevant fluids. The results obtained were integrated into the case constructions of various tubulopathies.

Results:

Tubular function was preserved in 41.1% of the testees. Tubular immaturity explained the findings in two other children. Idiopathic hypercalciuria (16.0 %), nephrogenic diabetes insipidus (8.9%) and acute renal failure (5.3 %) were the most frequent findings. In 14 of the testees, 10 tubulopathies were diagnosed were through deficiency rickets, hypophosphatasia, Leigh's disease, Bartter syndrome, Dent disease and tubular acidosis I, II and IV..

Conclusions:

The tubular study with morning urine samples allows the diagnosis of important tubulopathies in the pediatric ages.

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