Thyroid + Nutrients

Thyroid: TSH, Free T4, Free T3, Reverse T3, and TPO and thyroglobulin antibodies.

Nutrients:

• Ferritin: the protein that stores iron, and the most useful first marker of iron stores.
• Iron, TIBC and iron saturation: how much iron is circulating and how much capacity your blood has to carry it.
• Vitamin B12: needed for red blood cells and nerve function.
• Vitamin D, 25-hydroxy: the standard measure of your vitamin D status.

This panel suits people with hypothyroidism or Hashimoto's who still feel tired or foggy, or who notice hair shedding, even when their TSH looks acceptable. It also suits people with heavy periods, a plant-based diet, or long-term use of metformin or acid-reducing medication, all of which can lower iron or B12.

Consider testing when symptoms persist despite stable thyroid results, or when you start a new thyroid plan and want a baseline. If you start iron, B12 or vitamin D, ask your clinician when to recheck. It often takes about 3 months for levels to change meaningfully.

Test thyroid function 6 to 8 weeks after any dose change.

This panel requires fasting because of the iron test, so plan a morning draw.

• Thyroid medication: if you take levothyroxine or another thyroid medication, have your blood drawn before that day's dose and bring the dose with you. Keep taking your medication as prescribed otherwise.
• Biotin: high-dose biotin, common in hair, skin and nail supplements, can distort many of these lab results. Stop it at least 2 to 3 days before your draw.
• Iron supplements: they can raise your iron result for a while after a dose. Ask your clinician whether to skip yours for 24 hours before the draw.

Your report shows Quest's reference range next to each result. For the thyroid results, the common patterns are the same as for any thyroid panel: TSH usually moves in the opposite direction from thyroid hormone, and antibodies point to autoimmunity rather than current function.

For the nutrient results:

• Low ferritin is a strong sign of low iron stores, even before anemia develops.
• Normal or high ferritin does not always mean stores are adequate, because inflammation and liver disease can raise it.
• Low iron saturation with high TIBC is the typical iron deficiency pattern.
• Borderline B12 can need a follow-up test such as methylmalonic acid, which is not in this panel.
• Vitamin D targets vary between expert groups, so your clinician may use a different goal from the printed range.