In an interesting study, published recently in Indian Pediatrics, Sethi, et al. [1] have raised a very valid question about the practice of giving weekly vitamin K injections to neonates on antibiotics for more than one week. Antibiotics that are used in the treatment of neonatal infections may have different effects on vitamin K levels through different mechanisms of action [2]. Additionally, K1 and K3 isoforms, that are used here, based upon logistic obtainability may have different bioavailability, pharmacodynamic effect and hence, may produce a non-uniform effect [3]. Half-life (t½) of PIVKA-ll is more than 70 hours [4]; this t½ progressively increases with age. Hence, the duration of 7±2 days may not be a good enough interval to assess the fall (from 992 to non-significant levels of <2 ng/mL). The lack of standard reference for PIVKA levels in premature neonates further adds to the conundrum [5]. The t½ of Vit K dependent coagulation factors is only a few hours; estimation of easily available parameters like serum prothrombin level, probably would have been a better surrogate marker and more clinically applicable.

1. Sethi A, Sankar MJ, Thukral A, Saxena R, Chaurasia S, Agarwal R. Prophylactic vitamin K administration in neonates on prolonged antibiotic therapy: A randomized controlled trial. Indian Pediatr. 2019;56:463-7.

2. Allison PM, Mummah-Schendel LL, Kindberg CG, Harms CS, Bang NU, Suttie JW. Effects of a vitamin K-deficient diet and antibiotics in normal human volunteers. J Lab Clin Med. 1987;110:180-8.

3. Buitenhuis HC, Soute BA, Vermeer C. Comparison of the vitamins K1, K2 and K3 as cofactors for the hepatic vitamin K-dependent carboxylase. Biochim Biophys Acta. 1990;1034:170-5.

4. Shapiro AD, Jacobson LJ, Armon ME, Manco-Johnson MJ, Hulac P, Lane PA, et al. Vitamin K deficiency in the newborn infant: Prevalence and perinatal risk factors. J Pediatr. 1986;109:675-80.