No blood test can tell about anxiety disorders. Only detailed psychological assessment will be able to recognise anxiety disorders. As since childhood he is having anxiety or low threshold for stress, he might be having an anxious personality than having any anxiety disorder. Don't worry , every problem has solutions. Pls consult a psychiatrist for further assessment.
Next Steps
detailed childhood, family and personal history is required, also information about any substance use will be necessary.
Thyroid function test can help ruling out anxiety due to thyroid disorders which is also common
Health Tips
Seems a mild anxiety crosssectionaly, but needs to be assessed further.