This clinical mind map is organized around causes of fatigue arising from various organ systems, such as the endocrine system and the hematologic system. Fatigue is a very common problem, and patients may present describing fatigue as their only complaint or provide additional symptoms which may or may not point to an organ system. Initially, a clinician must consider all probable diagnoses in the order of more common to less common. Of the listed differentials, sleep disturbance is one of the most common underlying causes of fatigue.

Although an end stage organ failure of any kind can be potentially life-threatening, very few conditions presenting with fatigue give rise to urgent/emergent situations, because in case of urgent/emergent situations, patients are most likely going to present with additional symptoms such as dyspnea (in the case of heart failure), weight loss (in the case of metastatic cancer), and fever (in the case of infection). Patients with adrenal insufficiency may present with extreme fatigue and circulatory collapse without manifesting many other symptoms and signs.

Weighing and removing anchor bias involves first asking high yield questions, which in this case is the duration and then the organ/system specific questions. Sometimes, patients volunteer additional information such as the duration and symptoms pointing to certain organ systems, which may help a clinician to narrow differential diagnoses. A physical exam provides further information and a clinician must order labs and/or tests based upon a narrow set of differentials or a working diagnosis.

A helpful mnemonic to memorize differentials in this mind map is DAD HAS POCA HOCHA.