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Urinary ferritin; a potential noninvasive way to screen NICU patients for iron deficiency

Journal of Perinatology volume 41, pages 1419–1425 (2021)Cite this article

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Abstract

Objective

Building on our previous study, showing a correlation between ferritin in serum and urine, we conducted a feasibility evaluation, measuring urinary ferritin as a potential noninvasive screening test for iron deficiency among NICU patients.

Study design

This was a prospective analysis of paired serum/urine ferritin levels. We defined iron-limited erythropoiesis by a RET-He <5th percentile lower reference interval (<28 pg).

Results

We obtained 49 paired serum/urine samples from neonates judged as at-risk for iron deficiency. Urine ferritin (“corrected” for urine creatinine and specific gravity) correlated with serum ferritin (correlation coefficient of log10-transformed values 0.44). A corrected urine ferritin <12 ng/mL had a sensitivity of 82% (95% CI, 67–93%) and a specificity of 100% (CI, 66–100%) for detecting iron-limited erythropoiesis, with a positive predictive value of 100% (CI, 89–100%).

Conclusions

Measuring urinary ferritin in NICU patients is feasible. Since low values identify iron-limitation, this could become a useful noninvasive screen.

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Fig. 1: Log10-transformed ferritin concentrations in paired serum/urine collections from 49 NICU patients.
Fig. 2: ROC analysis.

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Acknowledgements

We thank Kendell R. German, MD, University of Washington, for reviewing the paper and making helpful suggestions. We also thank Vickie L. Baer, RN, NICU data research manager, for building the RedCap program, Susan Christensen, RN, NICU research nursing, for entering patients into the study, and the families, neonatologists, and neonatal nurse practitioners of Utah Valley Hospital, Provo, Utah, for their support of this study. We also thank Ryan Cordner, PhD, Department of Microbiology & Molecular Biology, Brigham Young University, Provo, UT, and Dennis Eggett, PhD, Department of Statistics, Brigham Young University, Provo, UT for assistance and advice.

Funding

The study was supported in part by grant U54DK110858 from the US Public Health Service, and by funds from Intermountain Healthcare Women and Newborns Research (to EG), and by funds from the Department of Pediatrics (to TMB), University of Utah Health, Salt Lake City, UT.

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Authors and Affiliations

  1. Intermountain Healthcare, Women and Newborns Clinical Program, Salt Lake City, UT, USA

    Erick Gerday, Jennifer B. Brereton, Jennifer O. Elmont, Robin K. Ohls & Robert D. Christensen

  2. Department of Pediatrics, Division of Neonatology, University of Utah Health, Salt Lake City, UT, USA

    Erick Gerday, Timothy M. Bahr, Robin K. Ohls & Robert D. Christensen

  3. Department of Nutrition, Dietetics, and Food Science, Brigham Young University, Provo, UT, USA

    Susan Fullmer

  4. Intermountain Healthcare, Clinical Laboratories, Murray, UT, USA

    Bruce A. Middleton

  5. Center for Iron and Heme Disorders, University of Utah, Salt Lake City, UT, USA

    Diane M. Ward

  6. Department of Pathology, University of Utah Health, Salt Lake City, UT, USA

    Diane M. Ward

  7. Department of Pediatrics, Division of Hematology/Oncology, University of Utah, Salt Lake City, UT, USA

    Robert D. Christensen

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  1. Erick Gerday
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Contributions

All authors reviewed and edited the paper, approved the final version, and take responsibility for the contents. The study was conceived, organized, and conducted by EG, JBB, JOE, SF, and RDC. The laboratory aspects were conceived and conducted by BAM and DMW. Data assembly, display, statistical analysis, and writing the initial paper draft, were performed by TMB, JBB, RKO, and RDC.

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Correspondence to Robert D. Christensen.

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Gerday, E., Brereton, J.B., Bahr, T.M. et al. Urinary ferritin; a potential noninvasive way to screen NICU patients for iron deficiency. J Perinatol 41, 1419–1425 (2021). https://doi.org/10.1038/s41372-020-0746-6

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