Utility of a Urine Screening Tool for Vitamin D Deficiency in Infants and Toddlers

Background: Vitamin D plays a key role in calcium absorption in the gut and in skeletal development. Vitamin D deficiency is common, affecting an estimated one billion people worldwide, including developed countries. Vitamin D deficiency causes rickets, the most common non-communicable disease of childhood. Rickets causes poor growth and skeletal deformities and, at its most severe, seizures and death. Recent data suggest that children with rickets have an increased risk for developing diabetes mellitus. Screening for vitamin D deficiency is not commonly done. It is generally diagnosed only after symptoms of rickets have developed. Prevention and treatment is simple and inexpensive. Hence, early detection of vitamin D deficiency through screening would be beneficial. Studies are urgently needed to validate such screening tests. Calcium balance is tightly regulated in the body and calcium loss in the urine (measured by the urine calcium-to-creatinine ratio) is a sensitive indicator of reduced calcium absorption, such as in vitamin D deficiency. Objective and Hypotheses. The objective of this study is to evaluate the urine calcium-to-creatinine ratio as a noninvasive and inexpensive screening test for vitamin D deficiency. Our hypotheses are 1) that the urine calcium-to-creatinine ratio correlates with blood vitamin D levels in infants and toddlers at risk for vitamin D deficiency and 2) that this test can be used to screen for vitamin D deficiency. Potential Impact. A validated screening tool would allow for the detection of vitamin D deficiency before the development of rickets, decreasing the morbidity and mortality of this common disease.