Low Energy? Blood Tests That Can Help Explain Why

Feeling tired all the time isn't normal - it's a symptom. The right blood tests can help identify why your energy is depleted.

Common Causes of Low Energy

• Iron deficiency (with or without anemia)
• Thyroid dysfunction
• B12 deficiency
• Vitamin D deficiency
• Blood sugar problems
• Chronic inflammation
• Poor sleep quality

The Energy Panel

Iron Status - Ferritin (most important) - Serum iron - TIBC - Transferrin saturation - CBC

Thyroid - TSH - Free T3 (the active hormone) - Free T4 - Thyroid antibodies

Vitamins - Vitamin B12 - Vitamin D - Folate

Metabolic - Fasting glucose - HbA1c - Fasting insulin

Inflammation - CRP - Ferritin (also elevated in inflammation)

The Most Missed Tests

Doctors often skip: - Ferritin: Checked only if CBC is abnormal - Free T3: Only TSH is checked - Fasting insulin: Only glucose is checked

These are often the most revealing tests for unexplained fatigue.

When Results Are "Normal"

If all results are normal but you're still tired: - Look at optimal vs. normal ranges - Consider additional testing (cortisol, sex hormones) - Evaluate sleep quality - Assess stress levels

References

• Vaucher, P., et al. (2012). Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. Canadian Medical Association Journal, 184(11), 1247-1254.
• Stabler, S. P. (2013). Clinical practice: vitamin B12 deficiency. New England Journal of Medicine, 368(2), 149-160.