Urinary ferritin as a non-invasive means of assessing iron status in young children

Najma A Moumin; Nina D'Vaz; Courtney Kidd; Andrea MacRae; Shao J Zhou; Toby Richards; Debra J Palmer; Luke E Grzeskowiak; Thomas R Sullivan; Tim J Green

doi:10.1016/j.tjnut.2024.04.040

Urinary ferritin as a non-invasive means of assessing iron status in young children

J Nutr. 2024 May 8:S0022-3166(24)00272-4. doi: 10.1016/j.tjnut.2024.04.040. Online ahead of print.

Authors

Affiliations

¹ Women and Kids Theme, South Australian Health and Medical Research Institute, Adelaide SA 5000, Australia; Discipline of Pediatrics, Faculty of Health and Medical Sciences, Adelaide Medical School, The University of Adelaide, Adelaide SA 5000, Australia. Electronic address: najma.moumin@sahmri.com.
² Telethon Kids Institute, University of Western Australia, Nedlands, WA 6009, Australia; School of Medical and Health Sciences, Edith Cowan University, Perth, WA 6027, Australia.
³ Telethon Kids Institute, University of Western Australia, Nedlands, WA 6009, Australia.
⁴ School of Agriculture, Food & Wine, The University of Adelaide, Urrbrae SA 5064, Australia; Robinson Research Institute, The University of Adelaide, Adelaide SA 5000, Australia.
⁵ School of Medicine, Division of Surgery, University of Western Australia, Perth WA 6009, Australia.
⁶ Telethon Kids Institute, University of Western Australia, Nedlands, WA 6009, Australia; School of Medicine, University of Western Australia, Crawley WA 6009, Australia.
⁷ Women and Kids Theme, South Australian Health and Medical Research Institute, Adelaide SA 5000, Australia; College of Medicine and Public Health, Flinders University, Bedford Park SA 5042, Australia.
⁸ Women and Kids Theme, South Australian Health and Medical Research Institute, Adelaide SA 5000, Australia; Discipline of Public Health, Faculty of Health and Medical Sciences, Adelaide Medical School, The University of Adelaide, Adelaide SA 5000, Australia.
⁹ Women and Kids Theme, South Australian Health and Medical Research Institute, Adelaide SA 5000, Australia; College of Nursing and Health Sciences, Flinders University, Bedford Park SA 5042, Australia.

PMID: 38729575
DOI: 10.1016/j.tjnut.2024.04.040

Abstract

Background: Iron deficiency (ID) is the most common nutritional deficiency affecting young children. Serum ferritin is the preferred biomarker for measuring iron status as it reflects iron stores; however, blood collection can be distressing for young children and can be logistically difficult. A Non-invasive means to measure iron status would be attractive to either diagnose or screen for ID in young children.

Objective: 1) To determine the correlation between urinary and serum ferritin in young children; 2) To determine if correcting urinary ferritin for creatinine and specific gravity improves the correlation; and 3) To determine a urine ferritin cut point to predict ID.

Methods: Validation study using paired serum and urine collected from 3-year-old children (n=142) participating in a longitudinal birth cohort study; the ORIGINS project in Perth, Western Australia. We calculated the sensitivity, specificity, positive, and negative predictive value of urinary ferritin in identifying those with ID at the clinical cut point used by the World Health Organization (serum ferritin <12 ng/mL).

Results: Urine ferritin, corrected for creatinine, correlated moderately with serum ferritin r=0.53 (0.40-0.64) and performed well in predicting those with ID (area under the curve 0.85, 95% CI 0.75-0.94). Urine ferritin < 2.28 ng/mg creatinine was sensitive (86%) and specific (77%) in predicting ID and had a high negative predictive value of 97%; however, the positive predictive value was low (40%) due to the low prevalence of ID in the sample (16%).

Conclusions: Urine ferritin showed good diagnostic performance for ID. The non-invasive biomarker maybe a useful screening tool to exclude ID in healthy young children; however, further research is needed in other populations.

Keywords: Australia; Iron status; Non-invasive biomarker; Serum Ferritin; The ORIGINS Project; Urinary Ferritin; Young Children.