The effect of phlebotomy and placement of an intravenous catheter on plasma catecholamine and serum copeptin concentrations.

OBJECTIVES

Limited data are available on the hormonal response of children to venepuncture or intravenous cannulation (IVC). Catecholamines (epinephrine (E) and norepinephrine (NE)) have been traditionally recognized as stress hormones. Copeptin, the carboxyl-terminus of the arginine vasopressin (AVP) precursor peptide, is also a known marker for stressful stimuli, including myocardial infarction, critical illness, and sepsis. We aimed to measure the above stress markers in response to IVC in the pediatric population.

METHODS

We measured plasma E, NE and serum copeptin concentrations in 100 children aged 5-17 years undergoing endocrine testing. Labs were drawn 1-3 min (min) after placement of IV cannula (baseline or 0 min) and then re-measured 20 min later (+20 min) while subjects rested in a quiet room.

RESULTS

Between 0 and 20 min, the median (IQR) NE (n=99) changed from 349 (244, 482) pg/mL to 253 (184, 348) pg/mL (p<0.001); E (n=54) changed from 57 (43, 116) pg/mL to 57 (38, 96) pg/mL (p=0.024); Copeptin changed from 9.4 (6.3, 15.2) pmol/L to 9 (5, 13) pmol/L (p<0.001). The mean decrease (delta) was 106 pg/mL for NE (28 %, p<0.001), 16 pg/mL for E (18 %, p=0.042) and 2.7 pmol/L for copeptin (17 %, p=0.012). There was no correlation between the decrease (expressed as a percentage) in NE vs. E, E vs. copeptin, and NE vs. copeptin.

CONCLUSIONS

Our data suggest that the stress of IVC induces a rapid increase in NE, E, as previously described, as well as copeptin levels. The copeptin decrement, concordant with the catecholamine trend in the minutes after IVC, supports this peptide (and AVP) as a rapid response marker of stress, and has unclear practical implications for copeptin measurements in evaluating fluid and sodium metabolism disorders in children.