title: A prospective longitudinal study to estimate the "adjusted cortisol percentile" in preterm infants.
abstract: The normal range of serum cortisol concentrations and the appropriate levels of circulating cortisol in different clinical situations in preterm infants are not well defined. This study aimed to evaluate the impact of perinatal factors on circulating cortisol levels in preterm infants and to create a quantitative model that could estimate the "adjusted cortisol percentile." Serial serum cortisol concentrations were measured in 209 infants ≤ 32 wk gestation on d 1, 4, 7, 14, and 21 of life. Seven perinatal factors or conditions that could affect circulating cortisol level were identified. Serum cortisol levels were higher on d 4 (p = 0.007) and d 7 (p = 0.007) but lower on d 21 (p = 0.001) compared with d 1. Serum cortisol was also higher in infants on nasal continuous positive airway pressure (p = 0.003); requiring a second vasopressor (p < 0.001); with intraventricular hemorrhage (≥ grade 3; p < 0.001); with histologic chorioamnionitis (p = 0.007); with severe lung disease (p = 0.046); and with decreasing GA (p < 0.001). A mathematical equation was proposed based on factors derived in this preliminary study for estimating the adjusted cortisol percentile. Frontline neonatologists could now access the equation on our Web site (http://www.sta.cuhk.edu.hk/pswong/ACortP.html) to calculate the adjusted cortisol percentile, which could potentially improve the interpretation of circulating cortisol in different clinical situations.
authors.affiliation: Department of Pediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, New Territories, Hong Kong. pakcheungng@cuhk.edu.hk
authors.forename: Pak C
authors.initials: PC
authors.lastname: Ng
authors.forename: Sam P S
authors.initials: SP
authors.lastname: Wong
authors.forename: Iris H S
authors.initials: IH
authors.lastname: Chan
authors.forename: Hugh S
authors.initials: HS
authors.lastname: Lam
authors.forename: Cheuk H
authors.initials: CH
authors.lastname: Lee
authors.forename: Christoper W K
authors.initials: CW
authors.lastname: Lam
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D008137:Longitudinal Studies; D008171:Lung Diseases / Q000097:blood; D008297:Male; D010913:Pituitary-Adrenal System / Q000502:physiology; D011247:Pregnancy; D011446:Prospective Studies
chemical_list: D006854:Hydrocortisone