SIADH

It is your Saturday shift at neurological ICU and you are called to a 35 year old patient with the history of a bike accident 12 days ago. During the morning ward round the patient is complaining of a strong headache and nausea. What will be your intervention based on new symptoms?
35
years
man
RR
16 /min
HR
87 /min
SpO2
98 %
BP
129/81 (97) mmHg
EKG
rythm: sinus
action: regular
Examination
HPI: Patient was admitted following a bike accident. at the time of admission the patient was confused with slurred speech. He had a headache and was nauseous. A cranial fissure and an acute subdural hematoma have been diagnosed, consequently the hematoma was evacuated. Other organ systems as well as the spine were not impaired. Two days after the evacuation a control brain CT scan was performed and didn´t show any new pathologies. The patient was weaned from the ventilator and extubated, he was stabilized, without any neurological symptoms. 10 days after the operation he was moved to the standard care unit.
PMH: hypothyreosis
DH: Euthyrox