Fluid intake and urinary osmolality in pediatric patients with functional constipation

Purpose This study aimed to evaluate fluid intake and urinary osmolality in pediatric patients with functional constipation. Methods This was a cross-sectional, case–control study that prospectively included two groups: 36 pediatric patients older than 4 years with functional constipation (Rome III criteria) who were consecutively admitted in a public tertiary pediatric gastroenterology outpatient clinic and 93 controls with normal bowel habits. The control group was recruited from a public school and did not have any of the characteristics of the Rome III criteria. Fluid and food intakes were assessed using a daily diet inquiry and 24 h recording method. Hypohydration was defined as osmolality greater than 800 mOsm/kg H 2 O in a spot urine sample. Results The age of the functional constipation group (median, 8.9 years; range 7.3–10.0 years) and the control group (8.8 years) was similar ( p = 0.51). The proportion of boys in the functional constipation group (76.6%; 25/36) was higher ( p = 0.01) than that in the control group (45.2%; 41/93). The total water intake of the functional constipation group (median 1566 mL) was lower ( p