Diagnosing male pattern baldness is often straightforward for your doctor.
Doctors diagnose it based on the appearance of the hair and the scalp. Your hair loss pattern will often be noticeable. They will also need to ask the affected patient about their medical history. This is a detailed medical history including questions about any hair loss patterns that run in your family.
Hair analysis is often done to assess poison related hair loss. This is a costly procedure, and when hair falls for poison induced reasons, the hair loss does not look like male pattern baldness.
It is best to visit an experienced physician in the field, and a professional clinic rather than those who immediately ask for a scalp biopsy or hair analysis.
A physician with expertise in the field would examine your scalp under a microscope (magnification/densitometer). They would then assess the cause of your hair loss, and identify the proper treatment for stopping it.
If you think you have male pattern baldness or any other significant hair loss, immediately visit a medical hair specialist, and have your assessment. An early diagnosis can help in preventing and stopping hair loss.