What thyroid tests should actually be run?

The panel we consider complete

• TSH – the pituitary signal that tells the thyroid how much hormone to produce; the most commonly ordered test, and often the only one
• Free T4 – the primary hormone your thyroid releases, measured in its active, unbound form
• Free T3 – the more biologically active hormone that T4 converts into; frequently left out of standard panels
• Reverse T3 – an inactive form that can build up when T4-to-T3 conversion isn’t working well, blocking active T3 from doing its job
• TPO antibodies – the primary marker for Hashimoto’s thyroiditis, the most common cause of hypothyroidism
• Thyroglobulin antibodies – a second autoimmune marker, sometimes elevated when TPO antibodies are not

Why TSH alone leaves gaps

TSH is a useful screening tool, but it’s an indirect measure — it reflects what the pituitary gland is signaling, not what’s actually reaching your tissues. It can sit within a normal range even when conversion from T4 to T3 is poor, when reverse T3 is elevated, or when autoimmune antibodies are already present. Someone can have Hashimoto’s for years with a persistently normal TSH before the numbers finally shift.

What we do with a full panel that a single value can’t show

Looking at all six markers together tells a more complete story than any one of them alone: whether there’s an autoimmune process underway, whether the thyroid is producing enough hormone, and whether your body is converting and using what it produces. That combination is what actually guides whether treatment makes sense, and what kind.