Why Am I So Tired When My Blood Work Is Normal? What Standard Testing Misses — How to read your existing labs better

Many patients with &ldquo;normal labs&rdquo; have lab data that contains useful information when re-examined against optimal ranges rather than reference ranges. Some specific patterns to look for: Ferritin between 10 and 40 in women, or between 30 and 70 in men: within reference range, but commonly associated with fatigue. The optimal range for energy is typically 70&ndash;90 for women and 100&ndash;150 for men. The full clinical picture requires evaluating whether this is iron deficiency (transferrin saturation low, iron low) or low-grade inflammation suppressing iron metabolism (ferritin spuriously elevated, CRP high, iron low). The two patterns look identical on a casual reading and require attention to the full panel. TSH above 2.5: within reference range in most laboratories but commonly associated with fatigue, weight gain, hair changes, and cold intolerance. Subclinical hypothyroidism is a real entity that the standard reference range obscures. Vitamin D below 40: within reference range in many laboratories but associated with worse immune function and worse symptoms. The optimal range is typically 50&ndash;80. B12 below 400: within reference range but commonly associated with functional B12 deficiency. Methylmalonic acid (a functional B12 marker) is the better test if serum B12 is between 200 and 500. Hemoglobin A1c above 5.4: within reference range but indicates impai