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Critically Ill Children Have Low Vitamin D-Binding Protein, Influencing Bioavailability of Vitamin D.
Ann Am Thorac Soc. 2015 Nov; 12(11):1654-61.AA

Abstract

RATIONALE

Vitamin D deficiency, often defined by total serum 25-hydroxyvitamin D (25[OH]D) <20 ng/ml, is common in critically ill patients, with associations with increased mortality and morbidity in the intensive care unit. Correction of vitamin D deficiency in critical illness has been recommended, and ongoing clinical trials are investigating the effect of repletion on patient outcome. The biologically active amount of 25(OH)D depends on the concentration and protein isoform of vitamin D-binding protein (VDBP), which is also an acute-phase reactant affected by inflammation and injury.

OBJECTIVES

We performed a secondary analysis of a cohort of critically ill children in which we reported a high rate of vitamin D deficiency, to examine how VDBP level and genotype would impact vitamin D status.

METHODS

We prospectively enrolled 511 children admitted to the pediatric intensive care unit over a 12-month period.

MEASUREMENTS AND MAIN RESULTS

We measured serum VDBP in 479 children. We genotyped single nucleotide polymorphisms rs7041 and rs4588 in the VDBP gene (GC) to determine haplotypes GC1F, GC1S, and GC2 in 178 subjects who consented, then calculated bioavailable 25(OH)D from serum 25(OH)D, VDBP, albumin, and GC haplotype. The median serum VDBP level was 159 μg/ml (interquartile range, 108-221), lower than has been reported in healthy children. Factors predicting lower levels in multivariate analysis included age <1 year, nonwhite race, being previously healthy, 25(OH)D <20 ng/ml and greater illness severity. In the subgroup that was genotyped, GC haplotype had the strongest association with VDBP level; carriage of one additional copy of GC1S was associated with a 37.5% higher level (95% confidence interval, 31.9-44.8; P < 0.001). Bioavailable 25(OH)D was also inversely associated with illness severity (r = -0.24, P < 0.001), and ratio to measured total 25(OH)D was variable and related to haplotype.

CONCLUSIONS

Physiologic deficiency of 25(OH)D in critical illness may be more difficult to diagnose, given that lower VDBP levels increase bioavailability. Treatment studies conducted on the basis of total 25(OH)D level, without consideration of VDBP concentration and genotype, may increase the risk of falsely negative results.

Authors+Show Affiliations

1 Department of Anesthesia, Perioperative and Pain Medicine, Division of Critical Care Medicine. 2 Department of Anaesthesia and.3 Division of Endocrinology, and. 4 the Clinical Research Center, Boston Children's Hospital, Boston, Massachusetts. 5 Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.6 Department of Orthopaedics, University of California at Los Angeles, Los Angeles, California.7 Nutrition and Health Sciences Program, Laney Graduate School, Emory University, Atlanta, Georgia.1 Department of Anesthesia, Perioperative and Pain Medicine, Division of Critical Care Medicine.1 Department of Anesthesia, Perioperative and Pain Medicine, Division of Critical Care Medicine.8 Drexel School of Medicine, Philadelphia, Pennsylvania; and.9 Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota.1 Department of Anesthesia, Perioperative and Pain Medicine, Division of Critical Care Medicine. 2 Department of Anaesthesia and.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

26356094

Citation

Madden, Kate, et al. "Critically Ill Children Have Low Vitamin D-Binding Protein, Influencing Bioavailability of Vitamin D." Annals of the American Thoracic Society, vol. 12, no. 11, 2015, pp. 1654-61.
Madden K, Feldman HA, Chun RF, et al. Critically Ill Children Have Low Vitamin D-Binding Protein, Influencing Bioavailability of Vitamin D. Ann Am Thorac Soc. 2015;12(11):1654-61.
Madden, K., Feldman, H. A., Chun, R. F., Smith, E. M., Sullivan, R. M., Agan, A. A., Keisling, S. M., Panoskaltsis-Mortari, A., & Randolph, A. G. (2015). Critically Ill Children Have Low Vitamin D-Binding Protein, Influencing Bioavailability of Vitamin D. Annals of the American Thoracic Society, 12(11), 1654-61. https://doi.org/10.1513/AnnalsATS.201503-160OC
Madden K, et al. Critically Ill Children Have Low Vitamin D-Binding Protein, Influencing Bioavailability of Vitamin D. Ann Am Thorac Soc. 2015;12(11):1654-61. PubMed PMID: 26356094.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Critically Ill Children Have Low Vitamin D-Binding Protein, Influencing Bioavailability of Vitamin D. AU - Madden,Kate, AU - Feldman,Henry A, AU - Chun,Rene F, AU - Smith,Ellen M, AU - Sullivan,Ryan M, AU - Agan,Anna A, AU - Keisling,Shannon M, AU - Panoskaltsis-Mortari,Angela, AU - Randolph,Adrienne G, PY - 2015/9/11/entrez PY - 2015/9/12/pubmed PY - 2016/9/2/medline KW - bioavailability KW - critical illness KW - haplotype KW - vitamin D KW - vitamin D–binding protein SP - 1654 EP - 61 JF - Annals of the American Thoracic Society JO - Ann Am Thorac Soc VL - 12 IS - 11 N2 - RATIONALE: Vitamin D deficiency, often defined by total serum 25-hydroxyvitamin D (25[OH]D) <20 ng/ml, is common in critically ill patients, with associations with increased mortality and morbidity in the intensive care unit. Correction of vitamin D deficiency in critical illness has been recommended, and ongoing clinical trials are investigating the effect of repletion on patient outcome. The biologically active amount of 25(OH)D depends on the concentration and protein isoform of vitamin D-binding protein (VDBP), which is also an acute-phase reactant affected by inflammation and injury. OBJECTIVES: We performed a secondary analysis of a cohort of critically ill children in which we reported a high rate of vitamin D deficiency, to examine how VDBP level and genotype would impact vitamin D status. METHODS: We prospectively enrolled 511 children admitted to the pediatric intensive care unit over a 12-month period. MEASUREMENTS AND MAIN RESULTS: We measured serum VDBP in 479 children. We genotyped single nucleotide polymorphisms rs7041 and rs4588 in the VDBP gene (GC) to determine haplotypes GC1F, GC1S, and GC2 in 178 subjects who consented, then calculated bioavailable 25(OH)D from serum 25(OH)D, VDBP, albumin, and GC haplotype. The median serum VDBP level was 159 μg/ml (interquartile range, 108-221), lower than has been reported in healthy children. Factors predicting lower levels in multivariate analysis included age <1 year, nonwhite race, being previously healthy, 25(OH)D <20 ng/ml and greater illness severity. In the subgroup that was genotyped, GC haplotype had the strongest association with VDBP level; carriage of one additional copy of GC1S was associated with a 37.5% higher level (95% confidence interval, 31.9-44.8; P < 0.001). Bioavailable 25(OH)D was also inversely associated with illness severity (r = -0.24, P < 0.001), and ratio to measured total 25(OH)D was variable and related to haplotype. CONCLUSIONS: Physiologic deficiency of 25(OH)D in critical illness may be more difficult to diagnose, given that lower VDBP levels increase bioavailability. Treatment studies conducted on the basis of total 25(OH)D level, without consideration of VDBP concentration and genotype, may increase the risk of falsely negative results. SN - 2325-6621 UR - https://www.unboundmedicine.com/medline/citation/26356094/Critically_Ill_Children_Have_Low_Vitamin_D_Binding_Protein_Influencing_Bioavailability_of_Vitamin_D_ L2 - http://www.atsjournals.org/doi/full/10.1513/AnnalsATS.201503-160OC?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -