Changes in appetite related gut hormones in intensive care unit patients: a pilot cohort study

The nutritional status of patients in the intensive care unit (ICU) appears to decline not only during their stay in the ICU but also after discharge from the ICU. Recent evidence suggests that gut released peptides, such as ghrelin and peptide YY (PYY) regulate the initiation and termination of meals and could play a role in the altered eating behaviour of sick patients. The aim of this study was to assess the patterns of ghrelin and PYY levels during the stay of ICU patients in hospital.

Sixteen ICU patients (60 +/- 4.7 years, body mass index (BMI) 28.1 +/- 1.7 kg/m2 (mean +/- standard error of the mean)) underwent fasting blood sample collections on days 1, 3, 5, 14, 21 and 28 of their stay at Hammersmith and Charing Cross Hospitals. Changes in appetite and biochemical and anthropometric markers of nutritional status were recorded. A comparison was made to a group of 36 healthy volunteers matched for age and BMI (54.3 +/- 2.9 years, p = 0.3; BMI 25.8 +/- 0.8 kg/m2 p = 0.2).

Compared to healthy subjects, ICU patients exhibited a significantly lower level of ghrelin (day one 297.8 +/- 76.3 versus 827.2 +/- 78.7 pmol/l, p < 0.001) during their stay in the ICU. This tended to rise to the normal level during the last three weeks of hospital stay. Conversely, ICU patients showed a significantly higher level of PYY (day one 31.5 +/- 9.6 versus 11.3 +/- 1.0 pmol/l, p < 0.05) throughout their stay in the ICU and on the ward, with a downward trend to the normal level during the last three weeks of stay.

Results from our study show high levels of PYY and low levels of ghrelin in ICU patients compared to healthy controls. There appears to be a relationship between the level of these gut hormones and nutritional intake.