Gender differences in the responses of serum insulin-like growth factor-1 and transthyretin (prealbumin) to trauma

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Abstract
To determine whether factors such as age, gender, and severity of injury should be considered when evaluating serum insulin-like growth factor (IGF)-1 and transthyretin concentrations as markers of nutritional status after trauma. A large, diverse group of patients was studied before the confounding effects of acute nutrient deprivation. Prospective, randomized, descriptive study. Emergency room of a university hospital. One hundred eight trauma patients. None. In this heterogeneous group of patients, Injury Severity Score ranged from 1 to 45 (11.5 +/- 10.3 [SD]), age ranged from 18 to 77 yrs (35 +/- 15.3 [SD]), and 68% were male and 32% were female. A venous blood sample was collected on admission and analyzed for serum IGF-1, transthyretin, albumin, and C-reactive protein concentrations. Relationships among variables were tested with multiple regression, Pearson's correlation coefficients, and analysis of variance. Gender, age, and severity of injury demonstrated strong and interactive effects on serum IGF-1 concentrations. IGF-1 concentrations were predicted with the following equations in women and men, respectively: y = 414 - 10.87(age) + 1.19(Injury Severity Score) + .09(age2); y = 454 - 10.87(age) - 2.57(Injury Severity Score) + .09(age2); (R2 = .35, p < .0001). The relationship between age and IGF-1 was curvilinear in both men and women. IGF-1 concentrations increased with age until approximately 57 yrs, and then decreased with increasing age. In women, IGF-1 concentrations increased with increasing severity of injury. In men, IGF-1 concentrations decreased with increasing Injury Severity Scores. This dissimilar response to injury between men and women was also seen in the significant interaction between gender and Injury Severity Score in predicting transthyretin concentrations (R2 = .32, p < .05). In men, transthyretin concentrations decreased significantly with severe injury; in women, transthyretin concentrations remained stable with severe injury. Albumin concentrations were predicted by injury severity and serum osmolality, but not gender. C-reactive protein, and time postinjury did not significantly influence the serum proteins (serum IGF-1, transthyretin, or albumin). Without consideration of age or severity of injury, mean concentrations of IGF-1, transthyretin, albumin, and C-reactive protein were not different between men and women, and were within normal expected ranges. Serum IGF-1 and transthyretin concentrations, measured without the confounding effects of acute nutrient deprivation, were influenced by the severity of the injury in patients suffering traumatic injury. Age was an important determinant of serum IGF-1 in men and women even in severe trauma. The present study indicated that men and women demonstrate different physiologic responses to trauma. Women responded to increasing severity of injury with increased serum IGF-1 and little change in transthyretin concentrations. In men, both IGF-1 and transthyretin concentrations decreased with severe injury. Interpretation of serum concentrations of IGF-1 and transthyretin as markers of nutritional status after trauma should include consideration of age, gender, and severity of injury.