title: Variation of Human Milk Glucocorticoids over 24 hour Period.
abstract: Human milk (HM) contains a complex array of hormones, including members of the glucocorticoid family. The predominant glucocorticoids, cortisol and cortisone may influence the growth and behaviour of the breastfed infant. However, little is understood of the factors regulating the levels of these hormones within HM. The aim of the study was to examine HM cortisol and cortisone concentration, measured in samples collected at each feed during a 24 hour period. Twenty three exclusively breastfeeding mothers collected milk, prior to and after each breastfeeding session over 24 hour period at 3.2(1.60) months. HM cortisol and cortisone levels were measured using high pressure liquid chromatography mass spectroscopy. Cortisone was the predominant glucocorticoid (3.40 ng/ml), and cortisol was detected in all samples (1.62 ng/ml). A positive correlation was found between cortisone and cortisol (r = 0.61, y = 1.93 ± 0.24, p < 0.0001). Cortisol and cortisone concentrations were significantly higher in feeds in the morning (2.97 ng/ml and 4.88 ng/ml), compared to afternoon (1.20 ng/ml and 3.54 ng/ml), evening (0.69 ng/ml and 2.13 ng/ml) and night (1.59 and 3.27 ng/ml). No difference was found between glucocorticoids level of the milk expressed for collection either before or immediately after the breastfeed, or between milk collected from the left or right breast. This study shows that HM glucocorticoid concentrations exhibit a 24 hour pattern, with highest peak levels in the early morning, reflecting the circadian pattern as previously reported in plasma. Thus, HM glucocorticoid concentrations are likely to reflect those in the maternal circulation.
authors.affiliation: Liggins Institute, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
authors.forename: Shikha
authors.initials: S
authors.lastname: Pundir
authors.affiliation: Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand.
authors.forename: Clare R
authors.initials: CR
authors.lastname: Wall
authors.affiliation: Liggins Institute, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
authors.forename: Cameron J
authors.initials: CJ
authors.lastname: Mitchell
authors.affiliation: Liggins Institute, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Thorstensen
authors.affiliation: School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Ching T
authors.initials: CT
authors.lastname: Lai
authors.affiliation: School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Donna T
authors.initials: DT
authors.lastname: Geddes
authors.affiliation: Liggins Institute, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand. d.cameron-smith@auckland.ac.nz.
authors.forename: David
authors.initials: D
authors.lastname: Cameron-Smith
mesh_terms: D000328:Adult; D001942:Breast Feeding / Q000379:methods; D003348:Cortisone / Q000737:chemistry / Q000378:metabolism; D005260:Female; D005938:Glucocorticoids / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000737:chemistry / Q000378:metabolism; D008895:Milk, Human / Q000737:chemistry*
chemical_list: D005938:Glucocorticoids; D003348:Cortisone; D006854:Hydrocortisone
keywords: Cortisol; Cortisone; Glucocorticoids; High-performance liquid chromatography; Human milk