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Calibration is an important source of variability in liquid chromatography mass spectrometry (LC-MS) methods for insulin-like growth factor 1 (IGF-1). This study investigated the impact of different calibrator matrices on IGF-1 measurements by LC-MS. Moreover, the comparability of immunoassays and LC-MS was assessed. Calibrators from 12.5 to 2009 ng/ml were prepared by spiking WHO international Standard (ID 02/254 NIBSC, UK) into the following matrices: native human plasma, fresh charcoal-treated human plasma (FCTHP), old charcoal-treated human plasma, deionized water, bovine serum albumin (BSA), and rat plasma (RP). A validated in-house LC-MS method was calibrated repeatedly with these calibrators. Then, serum samples from 197 growth hormone excess and deficiency patients were analysed with each calibration. The seven calibration curves had different slopes leading to markedly different patient results. The largest differences in IGF-1 concentration from the median (interquartile range) was observed with the calibrator in water and the calibrator in RP (336.4 [279.6–417.0] vs. 112.5 [71.2–171.2], p < 0.001). The smallest difference was observed with calibrators in FCTHP and BSA (141.8 [102.0–198.5] vs. 127.9 [86.9–186.0], p < 0.049). Compared to LC-MS with calibrators in FCTHP, immunoassays showed relevant proportional bias (range: −43% to −68%), constant bias (range: 22.84 to 57.29 ng/ml) and pronounced scatter. Comparing the immunoassays with each other revealed proportional bias of up to 24%. The calibrator matrix is critical for the measurement of IGF-1 by LC-MS. Regardless of the calibrator matrix, LC-MS shows poor agreement with immunoassays. Also, the agreement between different immunoassays is variable. [ABSTRACT FROM AUTHOR]

This pilot study evaluated a high-energy, high-protein, peptide-based, (medium-chain triglycerides) MCT-containing enteral tube feed (Nutrison Peptisorb Plus HEHP ® , Nutricia Ltd., Trowbridge, BA14 0XQ, UK.) containing 1.5 kcal/mL and 7.5 g protein/100 mL. Fifteen community-based, enterally tube-fed adults (42 (SD 16.3) years) received the intervention feed daily for 28 days, with gastrointestinal tolerance, compliance and nutrient intake assessed at baseline and after the intervention period. Incidence and intensity of constipation ( p = 0.496), nausea ( p = 1.000), abdominal pain ( p = 0.366) and bloating ( p = 0.250) remained statistically unchanged, yet the incidence and intensity of diarrhoea improved significantly after receiving the intervention feed (Z = -2.271, p = 0.023). Compliance with the intervention feed was significantly greater compared to the patient's baseline regimens (99% vs. 87%, p = 0.038). Compared to baseline, use of the intervention feed enabled patients to significantly increase total energy (1676 kcal/day (SD 449) to 1884 kcal/day (SD 537), p = 0.039) and protein intake (73 g/day (SD 17) to 89 g/day (SD 23), p = 0.001), allowing patients to better achieve energy (from 88% to 99%, p = 0.038) and protein (from 101% to 121%, p < 0.001) requirements. This pilot study demonstrates that a high-energy, high-protein, peptide-based, MCT-containing enteral tube feed maintains gastrointestinal tolerance and improves compliance, energy and protein intake in complex, enterally tube-fed, community-based adult patients, though more work is recommended to confirm this.

Background & Aims: Infants with complex medical conditions often display faltering growth due to elevated nutritional requirements, poor intake and intolerance of feeding with malabsorption and maldigestion. As a result their nutritional management can be extremely challenging and enteral nutritional support is required. This study aimed to investigate the effectiveness, tolerance and acceptability of nutritional support with a specially formulated, paediatric peptide feed in infants with complex disease and signs of growth faltering with their current nutritional management., Methods: This prospective intervention study investigated gastrointestinal (GI) tolerance, nutritional intake and compliance with feeding, anthropometry and growth in 18 infants (mean age 6.11 months ± 4.69, mean weight 4.97 kg ± 1.71) during 28 days of enteral nutritional support with a paediatric (1 kcal/ml) readymade peptide feed., Results: GI tolerance to nutritional support with a peptide enteral feed was good and either improved or remained stable over the study. Compliance was excellent (94.0% ± 12.6), total energy intake improved (+23 ± 42 kcal/kg, p = 0.037) and mean weight (0.61 kg ± 0.31, p = 0.0001), length (1.89 ± 1.77 cm, p = 0.0001), head circumference (1.33 ± 1.29 cm, p = 0.001), weight for length Z score (p < 0.05), and weight for age Z score (p < 0.05) significantly improved. Sixty one percent (n = 11) of the infants showed signs of increased growth velocity, moving upwards in terms of their centiles. All 18 infants continued with the paediatric, peptide enteral feed once the study was complete., Conclusions: This prospective study showed that nutrition support with a specially formulated, paediatric peptide readymade feed was well tolerated, helped to promote growth, and can be considered suitable for use in infants with complex disease and faltering growth who are unable to tolerate a whole protein feed., (Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.)