The refeeding syndrome has been reported without any evidence of prolopnged semistarvation, thus being different from the traditional disease.

The investigators wanted to investigate, if sodium infusions could be part of the explanation.

Background: Refeeding syndrome is conventionally connected to start of feeding after prolonged periods of semi-starvation and adaption. However, it is also described in acutely ill patients and in ICU patients without a history of adaption, but sometimes only defined as a drop in p-phosphate without clinical manifestations. The investigators hypothesize, that a positive sodium balance could induce the refeeding-like syndrome (RLS).

Method: Consecutive patients for acute, abdominal surgery were included and observed until discharge or up to seven days postoperatively with daily sodium and phosphate balance measurements.

Inclusion Criteria:

• age > 18 yr
• ready for acute surgery
• able to understand and cooperate.

Exclusion Criteria:

• pregnancy or breastfeeding
• renal insufficiency (p-creatinine>400 micr mol/l)
• re-operations
• expected hospital stay < 24 hours.

Consecutive, adult patients for acute, abdominal surgery were asked top be included and observed until discharge or up to seven days postoperatively with daily sodium and phosphate balance measurements.