The Use of an Automated Microsampling System for the Characterization of Growth Hormone Pulsatility in Newborn Babies

Abstract

To overcome the difficulties of studying hormone pulsatility in the newborn, we have developed an automated microsampling system that permits the measurement of hormones in small prediluted samples of blood (40 microL) taken at 10-min intervals over 12 h. The system has been validated in adult volunteers, and the error attributable to the dilution was <4%. Using this method in 10 preterm babies, we have been able to describe pulsatile changes in GH and have demonstrated a clear postprandial elevation in GH levels peaking 60 min after a feed. Fourier transform analysis indicated a pulse periodicity of 180 min in babies who were appropriate for gestational age (n = 6), but faster, co-dominant pulse periodicities of 90-100 and 140 min in babies who were small for gestational age (weight and length below the 10th centile) (n = 4). There was no significant difference between mean, peak, and baseline GH levels between the two groups.

Measuring luteinising hormone pulsatility with a robotic aptamer-enabled electrochemical reader

“…Multiple single-wire electrodes would be highly adaptable for multiplex hormone measurements in a single sample. A wire electrode may also be integrated with an automated blood collection system for hormone pulsatility measurement in real time 25,26 . Furthermore, E-AB in vivo continous sensing for small molecules has already been achieved in awake and ambulatory animals 27 , which also shows potential for our system after further refinement of the sensing performance in whole blood.…”

Using Aptamers as a Novel Method for Determining GnRH/LH Pulsatility

“…These attributes confer significant advantages over traditional antibody-based LH measurement. Additionally, this LH aptamer system can be adapted by inclusion of other aptamers to enable measurement of multiple proteins (including hormones) in a single sample [ 64 , 82 ]; by integration of a wire electrode with an automated blood collection system for real-time measurements [ 83 , 84 ]; and/or by incorporation of a microneedle skin patch [ 85 ] to measure hormones in dermal interstitial fluid. Furthermore, other electrochemical aptamer platforms have been successfully adapted and used for real-time continuous monitoring of pre- and post-administration drug levels in venous blood of ambulatory rats for ≥5 h [ 63 ].…”

More guidance on growth hormone deficiency

“…Between pulses, plasma concentrations of GH are low, making random sampling of little use in the diagnosis of GHD, 8 except in neonates, where the pulses are of higher amplitude and frequency. 9 Studies of pulsatile GH secretion can be performed by serial sampling every 20-30 minutes, either overnight or for 24 hours, GH secretion being expressed in various ways according to the concentrations obtained from multiple sampling. The reproducibility of such tests has been found to be poor, although better than that of stimulation tests, 10 and normally growing children may have low concentrations.…”