Fluconazole is the first-line agent in the treatment of invasive candidiasis. Studies showed inappropriate drug exposure causes high mortality in critically ill patients. Under-dosing and ineffective fluconazole trough serum concentrations were found in a recent retrospective study. Variability in fluconazole exposure can be easily measured with therapeutic drug monitoring. For patient groups who are at risk for drug underexposure, therapeutic drug monitoring can be valuable regards decreasing mortality.

Inclusion Criteria:

• Patient is 18 years or older.
• Treatment with fluconazole.
• Written informed consent obtained from patient.
• Written informed consent obtained from representative of patient.

Exclusion Criteria:

• Blood sampling not possible

All patients admitted to the University Medical Center Groningen who receive fluconazole