What Reasons Would You Need a Blood Test For?

What Reasons Would You Need a Blood Test For?


Blood tests are an important tool for monitoring and evaluating health. Getting routine bloodwork allows for the early detection of medical conditions and provides insight that supports proactive treatment.

In this article, we will explore common reasons why someone may need to have blood drawn and tested. We’ll cover routine health screenings as well as tests used to diagnose and manage specific diseases and conditions.

Annual Physicals

Doctors often order blood tests as part of an annual physical exam to screen for early signs of disease and assess risk factors. Testing levels of cholesterol, blood sugar, minerals, proteins, enzymes and other markers is key for evaluating overall health status.

Preventative Care

Blood tests help guide preventative care. For example, thyroid hormone levels impact many body functions. Checking TSH helps determine if medication may be needed to prevent thyroid problems. Testing vitamin D levels determines if supplementation should be started to maintain strong bones and immune function.

Prior to Surgery

Doctors order bloodwork before surgeries to check blood cell counts and ensure the body can safely handle anesthesia and recover properly afterwards.

Diagnosing Conditions

When evaluating symptoms, doctors order blood tests to aid diagnosis of conditions like:

  • Anemia – Identified through complete blood count tests and other blood markers.
  • Kidney disease – Assessed by testing kidney function through markers such as creatinine.
  • Liver disease – Revealed through liver enzymes levels like AST and ALT.
  • Infections – Detected by the presence of antibodies and other immune system markers.

Ongoing Disease Management

Many conditions require blood testing to monitor disease progression and treatment effectiveness. For example, the hemoglobin A1C test allows doctors to manage patients with diabetes by tracking average blood sugar levels over a 3 month span. This helps guide medication and lifestyle change recommendations.


What blood tests should adults get yearly?

A routine complete blood count, metabolic panel checking liver/kidney function and electrolyte balance, cholesterol panel, blood sugar, and vitamin D level check are common baseline yearly tests for adults.

When would a doctor order a complete blood count test?

A CBC may be ordered as part of an annual physical, before surgery, or to help diagnose conditions with symptoms like fatigue, bruising or infection.

Why check vitamin D levels in the blood?

We get vitamin D from food, supplements and sun exposure. Checking levels helps determine if someone is deficient, at risk for bone/muscle weakness, fatigue, or immune dysfunction.

What blood markers help identify heart disease risk?

Doctors look at cholesterol panels checking total, HDL, LDL and triglycerides levels. C-reactive protein and homocysteine may also be tested to reveal inflammation/plaque buildup in arteries.

How often should A1C be checked when managing diabetes?

Hemoglobin A1C gives a picture of average blood sugar over months. Checking every 3-6 months helps create an accurate pattern analysis to guide medication and lifestyle adjustments for optimal diabetes control.