Whenever a patient reports low energy, I always recommend bloodwork. When it comes to investigating fatigue, blood tests can be very helpful in identifying potential underlying causes. While there isn’t a single “best” blood test for fatigue, several tests can provide valuable information. Specific tests that are recommended will vary depending on an individual’s symptoms, medical history and the suspected cause of the fatigue.

Here are my top tests that I recommend for every patient:

• A Complete Blood Count (CBC): This test measures different components of your blood, such as red and white blood cells and platelets. It can help detect conditions like anemia, which can contribute to fatigue.

• Thyroid Function Tests: These tests evaluate the levels of thyroid hormones (such as T3 and T4) and thyroid-stimulating hormone (TSH). Thyroid imbalances, like hypothyroidism can cause fatigue.

• Iron Testing: There are many tests to assess iron levels in the blood, including ferritin, iron, and total iron-binding capacity. Low iron levels or iron-deficiency anemia can lead to fatigue.

• Vitamin D: Vitamin D deficiency has been linked to fatigue in some individuals. Testing the blood levels of vitamin D can help determine if supplementation is necessary. It is important to test vitamin D to determine the appropriate level of supplementation.

Other testing that may be helpful depending on your case include:

• Electrolyte Levels: Electrolytes, such as sodium, potassium, and magnesium, play a crucial role in maintaining proper bodily function. Imbalances in these electrolytes can lead to fatigue and other symptoms.

• Liver Function Tests: These tests evaluate liver enzymes, bilirubin, and other markers to assess liver health. Certain liver conditions can cause fatigue.

• Kidney Function Tests: Blood tests like creatinine and blood urea nitrogen (BUN) can assess kidney function. Kidney problems can contribute to fatigue.

• Blood Glucose Levels: High or low blood sugar levels can affect energy levels. Testing for fasting glucose or hemoglobin A1C (a 3-month average measure of glucose control) can provide insight into potential blood sugar abnormalities. Another test that I often run in patients is fasting insulin. If elevated, this can contribute to blood sugar highs and low. This test can still be elevated in patients with normal blood glucose and A1C levels. If the patient has a family history of diabetes, or evidence of elevated testosterone (irregular periods, excess facial hair or body hair, acne, or hair loss) then I will almost always recommend testing fasting insulin.

• Inflammatory Markers: Tests like C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) can indicate the presence of inflammation in the body. Chronic inflammation can lead to fatigue. This test may be important if you have an autoimmune condition, a family history of autoimmune conditions, or have evidence of chronic inflammation in the body.

It is important to note that bloodwork is just the beginning of our investigations into the cause of your fatigue. Blood tests are just one part of a comprehensive evaluation. If bloodwork comes back normal, other areas to investigate include: food sensitivities, chronic stress and/or burnout, sleep problems, depression, yeast overgrowth in the body, amongst others.

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