Protein turnover, lipolysis, and endogenous hormonal secretion in critically ill children.
OBJECTIVE
The catabolic state is a major contributor to morbidity and mortality of critical illness and may be related to endocrine changes. We studied whether protein and lipid turnover correlate with insulin and growth and thyroid hormone plasma levels in critically ill infants.


METHODS
Prospective clinical study.


METHODS
Pediatric intensive care unit.


METHODS
Twelve critically ill children and ten age-matched controls.


METHODS
We measured lipolysis and protein turnover by infusing albumin-bound uniformly 13C palmitic acid and 2H3-leucine for 3 hrs and 2H5-glycerol for 5 hrs to critically ill infants. Simultaneously, we measured serum growth hormones, insulin, C-peptide, thyroid-stimulating hormone, T4, T3, albumin, retinol binding protein (RBP), and prealbumin. Hormone and serum protein levels were also measured in six children when recovered from critical illness. Ten healthy age-matched children served as controls for hormone serum levels comparison.


RESULTS
Palmitic acid and glycerol turnover were 5.6 +/- 2.2 micromol/kg/min and 12.2 +/- 7.3 micromol/kg/min, respectively, whereas alpha-ketoisocaproic turnover was 4.9 +/- 2.8 micromol/kg/min. Alpha-ketoisocaproic turnover positively correlated (R = 0.7, p = .03) with duration of pediatric intensive care unit admission and with prealbumin and RBP serum levels (R = 0.9, p = .001). Insulin-like growth factor binding protein (IGFBP)-2 was significantly higher and IGFBP-3 was significantly lower in critically ill children (p = .03 and p = .04 vs. recovery phase, respectively). No other hormonal differences were found. Serum albumin was significantly lower in sick children. We found a significant correlation between prealbumin and RBP and IGFBP-3 (R = 0.6, p = 0.03 and R = 0.6, p = .04, respectively). Alpha-ketoisocaproic turnover positively correlated with IGFBP-1 (R = 0.79, p = .01) and did not correlate with insulin-like growth factor I (R = -0.5, p = .15 [not significant]) No other correlations were found. Lipid turnover measurements did not correlate with any endogenous hormone levels or with duration of critical illness.


CONCLUSIONS
Protein turnover but not lipolysis correlated with a persisting critically ill condition, serum prealbumin, RBP, and plasma IGFBP-1.
Cogo
Paola E
PE
Department of Pediatrics, Azienda Ospedaliera of Padova, Italy. paolac@child.pedi.unipd.it
Carnielli
Virgilio P
VP
Rosso
Federica
F
Cesarone
Arianna
A
Giordano
Giuseppe
G
Faggian
Diego
D
Plebani
Mario
M
Barreca
Antonina
A
Zacchello
Franco
F
D002096:C-Peptide / Q000378:metabolism; D002250:Carbon Radioisotopes; D002675:Child, Preschool; D016638:Critical Illness; D005990:Glycerol / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism; D007651:Keto Acids / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D008066:Lipolysis / Q000502:physiology*; D019308:Palmitic Acid / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D012177:Retinol-Binding Proteins / Q000378:metabolism; D054839:Retinol-Binding Proteins, Plasma; D013972:Thyrotropin / Q000378:metabolism; D013974:Thyroxine / Q000378:metabolism; D014284:Triiodothyronine / Q000378:metabolism
D002096:C-Peptide; D002250:Carbon Radioisotopes; D007328:Insulin; D018969:Insulin-Like Growth Factor Binding Proteins; D007651:Keto Acids; D011506:Proteins; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; D014284:Triiodothyronine; D019308:Palmitic Acid; C013082:alpha-ketoisocaproic acid; D013972:Thyrotropin; D013006:Growth Hormone; D007930:Leucine; D005990:Glycerol; D013974:Thyroxine