What is malaise syndrome and can it be diagnosed with a blood test?

Fatigue : Another word for fatigue. Work up includes a detailed history, physical exam an some labs. Please see your phsician.

???: Perhaps you are referring to chronic fatigue syndrome? To my knowledge, there are no lab tests that can diagnose it. It's a clinical diagnosis.

Malaise syndrome: There is no blood test for malaise syndrome. Malaise is a general term to mean "feeling unwell." although somewhat controversial, chronic fatigue syndrome is said to be associated with post-exertional malaise such as fatigue, light-headedness, muscle or joint pain, cognitive dysfunction, headache, nausea, weakness, trembling or insomnia.