Sepsis: This condition is characterized by a systemic inflammatory response to infection, which can lead to hypotension (septic shock), fever, and thrombocytopenia due to consumption of platelets. The combination of these symptoms in a patient suggests a severe infection that could be bacterial, viral, or fungal in origin.

Disseminated Intravascular Coagulation (DIC): A condition that can be triggered by severe infection, trauma, or malignancy, leading to both clotting and bleeding as the coagulation system is activated. It can cause thrombocytopenia, hypotension due to bleeding or shock, and fever if there's an underlying infection.
Meningococcemia: A severe infection caused by Neisseria meningitidis, which can present with fever, hypotension, and thrombocytopenia. The infection can lead to septic shock and disseminated intravascular coagulation.
Viral Hemorrhagic Fever (VHF): Certain viral infections like Ebola, Lassa fever, or dengue hemorrhagic fever can cause fever, thrombocytopenia, and hypotension due to vascular leakage and coagulopathy.

Bacteremia or Endocarditis: Although less common, bacteremia (bacteria in the blood) or endocarditis (infection of the heart valves) can present with these symptoms and are critical to diagnose early due to their high mortality rates if left untreated.
Toxic Shock Syndrome: Caused by bacterial toxins, typically from Staphylococcus aureus or Streptococcus pyogenes, this condition can lead to rapid onset of hypotension, fever, and can be associated with thrombocytopenia.
Hantavirus Syndrome: A viral infection that can cause fever, thrombocytopenia, and hypotension, often associated with renal failure and respiratory distress.

Thrombotic Thrombocytopenic Purpura (TTP): A rare blood disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, renal failure, and neurological symptoms. While it can cause thrombocytopenia, the presence of fever and hypotension would be less typical presentations.
Hemophagocytic Lymphohistiocytosis (HLH): A rare disorder of the immune system where the body produces too many activated immune cells called macrophages and lymphocytes. It can cause fever, thrombocytopenia, and hypotension but is much less common than other diagnoses listed here.
Leptospirosis: A zoonotic infection caused by Leptospira bacteria, which can lead to a wide range of symptoms including fever, thrombocytopenia, and in severe cases, hypotension due to Weil's disease. It's less common in urban settings without exposure to contaminated water.