The Association between Serum 25-Hydroxy Vitamin D Level and Urine Cathelicidin in Children with a Urinary Tract Infection.

OBJECTIVE: Cathelicidin is an important antimicrobial peptide in the urinary tract. Cathelicidin expression is strongly stimulated by 1,25-dihydroxy vitamin D in epithelial cells, macrophages/monocytes, and neutrophils. Vitamin D and cathelicidin status in children with urinary tract infection (UTI) caused by Escherichia coli is unknown. To establish the relationship between serum vitamin D and urine cathelicidin levels in children with a UTI caused by Escherichia coli. METHODS: Serum 25-hydroxy vitamin D and urine cathelicidin levels were measured in 36 patients with UTI (mean age 6.8±3.6 years, range: 0.25-12.6 years) and 38 controls (mean age 6.3±2.8 years, range: 0.42-13 years). RESULTS: There were no significant differences in urine cathelicidin levels between the study and control groups (p>0.05). Eight (22.2%) patients in the study group and 21 (58.3%) children in the control group were found to have sufficient vitamin D (≥20 ng/mL). Patients with sufficient vitamin D had higher urine cathelicidin levels than the controls with sufficient vitamin D (respectively 262.5±41.1 vs. 168±31.6 ng/mL, p=0.001). There were no significant differences between the patients and controls with insufficient vitamin D (p>0.05). CONCLUSION: The children with vitamin D insufficiency may not be able to increase their urine cathelicidin level during UTI caused by Escherichia coli. There is a need of prospective studies in order to prove a beneficial effect of vitamin D supplementation for the restoration of cathelicidin stimulation and consequently for prevention of UTI recurrence.

Comparison between daily supplementation doses of 200 versus 400 IU of vitamin D in infants.

The daily supplementation of vitamin D is mandatory for infants. However, there are still conflicting opinions about the exact daily dose. Thus, we aimed to evaluate a daily supplementation dose of 200 IU is sufficient and compared the supplementation doses of 200 and 400 IU per day. One hundred and sixty-nine infants were randomly assigned to two groups (group 1, 200 IU/day; group 2, 400 IU/day) and there were 75 infants in group 1 and 64 were in group 2 with a total number of 139. The median levels of 25-hydroxyvitamin D3 were significantly increased in group 2 at the age of 4 months (group 1, 39.60 mcg/L; group 2, 56.55 mcg/L; p < 0.0001). We clearly demonstrated that at the age of 4 months, none of the infants on the group 2 had a serum level of 25-hydroxyvitamin D3 less than 30 mcg/L. However, 21.3% of the infants in group 1 had a level below 30 mcg/L. Thus, in order to avoid vitamin D deficiency and rickets, we recommend supplementation dose of vitamin D at 400 IU/day as a safe and effective dose.