Parathyroid hormone-vitamin D dynamics vary according to the definition of vitamin D deficiency in newborn infants

• Published in: Bone (New York, N.Y.) Vol. 175; p. 116862
• Main Authors: Weiler, Hope A., Fu, Wen Hsuan, Razaghi, Maryam, Gharibeh, Nathalie, Vanstone, Catherine A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2023
• Subjects: Newborn infant; Parathyroid hormone; Vitamin D; LOD; VDSP; PTH; VDSCP; Vitamin D; Parathyroid hormone; Newborn infant; NIST; 25(OH)D; GA; AGA; DEQAS; CLIA; BMI
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/j.bone.2023.116862

Parathyroid hormone (PTH) is an indirect functional indicator of vitamin D status. Risk of vitamin D deficiency, assessed using circulating 25-hydroxyvitamin D (25(OH)D), is defined as <30 nmol/L by the National Academy of Medicine and alternatively <25 nmol/L in the global consensus recommendation on prevention and management of nutritional rickets. To test PTH concentrations and the odds for elevated values according to vitamin D deficiency cut-points (<30 nmol/L, or <25 nmol/L) in newborn infants. Healthy term-born infants (n = 858) were recruited from Montreal, Canada (2016–2019). Obstetric data were obtained from medical records, and demographic factors surveyed. Immunoassays were used to measure newborn (24–36 h) serum PTH and 25(OH)D; 25(OH)D was standardized to National Institute of Standards and Technology (NIST) standard reference materials. Serum PTH was log-transformed before comparing serum 25(OH)D groups (<30 vs. ≥30; or <25 vs. ≥25 nmol/L) using ANCOVA adjusted for infant sex, type of delivery, parity, race, and family income. The odds of elevated PTH (>71.48 pg/mL) were tested using logistic regression, adjusted for the same covariates. Infants (50.2 % female) were 39.6 ± 1.0 weeks gestational age (mean ± SD), and 3.41 ± 0.38 kg. Median serum 25(OH)D was 45.4 (IQR 23.2) nmol/L; 20.5 % had serum 25(OH)D < 30 nmol/L, and 12.4 % <25 nmol/L. Median serum PTH was 30.72 (IQR 33.90) pg/mL, elevated in 12.7 % overall, and higher in infants born with serum 25(OH)D < 25 vs. ≥25 nmol/L (35.96 (IQR 39.20) vs. 30.36 (IQR 32.93) pg/mL, p = 0.0158). The odds of elevated PTH were higher when serum 25(OH)D was <25 nmol/L (ORadj 2.13, 95 % CI: 1.23, 3.69). PTH concentration and the odds of being elevated did not differ according to the 30 nmol/L cut-point. Based on this study, the definition of vitamin D deficiency relative to bone health as set by the National Academy of Medicine (<30 nmol/L) exceeds the threshold at which PTH is elevated in newborn infants. •Vitamin D deficiency is defined as <30 or <25 nmol/L of serum 25-hydroxyvitamin D.•We studied parathyroid hormone (PTH) in serum of newborns using both thresholds.•PTH concentrations were higher only when tested using the <25 nmol/L threshold.•The odds of elevated PTH were doubled when 25-hydroxyvitamin D was <25 nmol/L.•This suggests that PTH is an acute biomarker of vitamin D deficiency in newborns.