[Urinary excretion of calcium, uric acid and citrate in healthy children and adolescents].
OBJECTIVE
To obtain regional reference values for calcium, uric acid and citrate urinary excretion and establish a correlation between those excretions in 24-hour urine sample and single urine sample for their use in clinical practice.


METHODS
A hundred and twenty-five healthy children and adolescents were randomly chosen and submitted to the following protocol: clinical examination, biochemical analysis of blood, blood cell count, parathormone, 24-hour urine, fasting urine sample and stool test.


RESULTS
The maximum value of calcium excretion in 24-hour urine was 3.75 mg/kg; in mg/dl of the glomerular filtration rate, it was 0.10; and for the calcium/creatinine (mg/dl) ratio in the fasting urine sample was 0.25. Positive correlation was observed between calcium excretion in the 24-hour urine and the fasting sample (mg/dl and mg/dl of glomerular filtration rate). The maximum values of uric acid excretion in 24-hour urine were 600, 450, and 320 mg and 13, 15 and 18 mg/kg for adolescents, school and preschool children, respectively; in mg/dl of glomerular filtration rate, in the fasting urine sample, it was 0.47. Positive correlation was observed for the uric acid excretion in 24-hour urine and fasting urine samples. The mean values for the citrate excretion in 24-hour urine were 1.6, 1.1 and 0.5 mmol for adolescents, school and preschool children, respectively; for citrate/creatinine ratio, in the fasting urine sample the mean value was 0.3.


CONCLUSIONS
The calcium and uric acid excretion in 24-hour urine showed correlation with those in the fasting urine sample, which allows their use for metabolic diagnosis, population studies and follow-up of patients with hypercalciuria and hyperuricosuria without voiding control; the citrate/creatinine ratio in the fasting urine sample can be used for controlling patients with hypocitraturia.
Penido
Maria Goretti Moreira Guimarães
MG
Pediatria, Universidade Federal de Minas Gerais, Belo Horizonte, MG. gabrielp@gold.com.br
Diniz
José Silvério Santos
JS
Guimarães
Milena Maria Moreira
MM
Cardoso
Rodrigo Barbosa
RB
Souto
Marcelo Ferraz de Oliveira
MF
Penido
Mariana Guimarães
MG