Prolactin is a polypeptide hormone with a short half-life and multiple physiological effects. Low prolactin in infancy is associated with neonatal respiratory distress and infant irritability, and changes in paediatric prolactin are linked with gonadal axis activation and growth hormone excretion. Despite these many associations, our understanding of the normal developmental physiology of prolactin in children is incomplete.
The aim of this study is to identify the normal physiology of prolactin secretion in infancy and childhood via meta-analysis of published paediatric data.
A literature search using the search terms ‘p(a)ediatric’, ‘prolactin’, and ‘reference interval’,was completed via Pubmed and Ovid Medline databases. Additional MeSH and keyword phrase utilisation ensured inclusion of all appropriate studies. Prolactin data for children aged 0-18 years were converted to mIU/L. Data from different analysers cannot be directly compared, therefore we overlaid the median trend of each analyser to assess temporal physiological variation. A weighted average was calculated to determine a schematic nomogram for paediatric prolactin.
Fourteen studies of paediatric prolactin from prematurity to 18 years were found, and 7915 measurements included. The median line derived for each available age partition, and the fold increase in the median from baseline was calculated. Analysis of overlay data shows the prolactin nadir is in mid childhood (5-7 years) with the highest peak occurring soon after birth in both pre-term (12 fold) and term (14 fold) newborns, down trending in the first year of life to eventually reach the pre-pubertal nadir, followed by a slight pubertal increase (1.6 fold). There was no sex difference.
This meta-analysis demonstrates the physiology of paediatric prolactin production. Investigation of the cause and purpose of the prolactin neonatal peak is planned through analysis of a large dataset at our centre, with review of the clinical course of infants found to have outlying low prolactin.