title: Clinical and laboratory characteristics of neonatal hypocalcemia.
abstract: OBJECTIVE
  To describe the clinical characteristics of full-term neonates with hypocalcemia and to suggest factors associated with neonatal hypocalcemia.
  
  
  METHODS
  The medical records of full-term neonates with hypocalcemia were reviewed. Hypocalcemia was defined as an ionized calcium (iCa) concentration of <4 mg/dL. Parathyroid hormone (PTH) insufficiency was defined as a serum PTH level of <60 pg/mL or a serum phosphorus level higher than the serum calcium level in the presence of hypocalcemia.
  
  
  RESULTS
  Fifty-three neonates were enrolled. The median age at diagnosis of hypocalcemia was 3 days. In all the neonates, formula feeding predominance was observed. Thirty-eight neonates (69.8%) were compatible with PTH insufficiency. The number of formula-fed neonates was significantly higher than that of breast-fed patients among neonates with PTH insufficiency (P=0.017). Intact PTH was negatively correlated with serum phosphorus levels. Twelve out of 14 neonates (85.7%) had 25-hydroxy vitamin D (25OHD) levels <20 ng/mL and 9 neonates (64.3%) had 25OHD levels <10 ng/mL. Twenty-one neonates had hypocalcemic tetany. The serum calcium and iCa concentrations of neonates with tetany were 4.2-8.3 mg/dL and 1.85-3.88 mg/dL, respectively. Three neonates showed symptomatic hypocalcemia with calcium levels over 7.5 mg/dL. Among the 16 neonates who underwent electroencephalography (EEG), 12 had abnormalities, which normalized after 1-2 months.
  
  
  CONCLUSIONS
  Formula milk feeding, PTH insufficiency and low serum vitamin D concentration are associated with the development of neonatal hypocalcemia. Symptoms such as tetany and QT interval prolongation can develop in relatively mild hypocalcemia. Moreover, transient neonatal hypocalcemia can cause transient EEG abnormalities.
authors.affiliation: Department of Pediatrics, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Won Im
authors.initials: WI
authors.lastname: Cho
authors.affiliation: Department of Pediatrics, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Hyeoh Won
authors.initials: HW
authors.lastname: Yu
authors.affiliation: Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Hye Rim
authors.initials: HR
authors.lastname: Chung
authors.affiliation: Department of Pediatrics, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Choong Ho
authors.initials: CH
authors.lastname: Shin
authors.affiliation: Department of Pediatrics, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Sei Won
authors.initials: SW
authors.lastname: Yang
authors.affiliation: Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Chang Won
authors.initials: CW
authors.lastname: Choi
authors.affiliation: Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Beyong Il
authors.initials: BI
authors.lastname: Kim
keywords: Hypocalcemia; Newborn infant; Parathyroid hormone; Tetany