- Pulmonary: Hypoxemia, Hypercarbia, Pneumonia, Pulmonary embolism
- Cardiac: Heart failure, heart attack, hypotension, Hypertensive encephalopathy
- Renal: Uremia, Hypovolemia
- Heme-Oncology: Malignancy, including para-neoplastic syndromes, Anemia
- Endocrine: Hyper/hyponatremia, Hypercalcemia, Hyper/hypoglycemia, Hypo/hyperthyroidism
- Neuro and Infections - see under main Delirium categories
- Above is not exhaustive list - can have other significant target organ system disease contributing. Multi-system organ dysfunction possible too.