Full thyroid panel (TSH, free T4, free T3, reverse T3, thyroid antibodies)

ND-recommended test reviewed: full thyroid panel (TSH, free T4, free T3, reverse T3, thyroid antibodies).
Indications reviewed: no validated basis for ordering the full bundle as a first-line or routine test; TSH result: ____ (date ____), or not yet checked.
Not ordered as a bundle. Rationale discussed: guidelines recommend a staged approach starting with TSH alone. Ref: OAML thyroid guideline 2007; NICE NG145 2019.
Patient informed test available privately via ND. Patient given info page: https://labs.ajaxharwoodclinic.com/full-thyroid-panel/patient
Revisit if: TSH result comes back abnormal, or new symptoms suggestive of thyroid dysfunction develop.

Indicated when

None recorded.

Not indicated when

• —Ordering TSH, free T4, free T3, reverse T3, and thyroid antibodies together as a first-line or routine bundle, instead of starting with TSH and adding tests only as indicated [1, 2]
• —Using a urine thyroid hormone panel as a substitute for standard serum TSH and free T4 testing: no guideline reviewed for this record recommends urine thyroid hormone measurement for diagnosis or monitoring

Why not

Every thyroid-testing guideline reviewed for this batch, Canadian and international, recommends a staged ("cascading") approach that starts with TSH and adds free T4, free T3, or antibodies only when the TSH result or clinical picture calls for it [1, 2]. Ordering the full set at once, especially with reverse T3 included, does not follow any of those pathways: it raises the number of borderline or hard-to-interpret results that can trigger further testing or treatment without a validated basis, at added cost. The individual components each have their own valid uses in specific situations, which is exactly why bundling them together as a default, first-line panel has no validated basis as a strategy.

Better first step

Start with TSH alone. Reflex to free T4 if TSH is high, or to free T4 and free T3 if TSH is low; add TPO antibodies if TSH is abnormal or borderline; reserve reverse T3 for no primary-care indication identified in this session ([1]; [2]; see the individual test entries for each).

Typical ND rationale

An ND may order a full or comprehensive thyroid panel, including reverse T3 and antibodies, in one visit, reasoning that thyroid dysfunction can present in patterns a single TSH would miss and that getting the full picture at once saves the patient a second blood draw if something turns out abnormal.

Ontario coverage & CONO orderability

OHIP status

unverified

The panel is not itself a single line item; it is a bundle of separately billed tests whose individual Ontario coverage differs (TSH insured, free T3 insured, free T4 and TPO antibodies unverified, reverse T3 not found in the 2026 community Schedule). A urine thyroid hormone panel does not appear in the 2026 Schedule at all. Because the components' status differs and the bundle itself is not a Schedule listing, overall status is recorded as unverified; see each component's own entry for its specific status. ND-ordered testing is patient-paid regardless (Reg. 552 s.22).

CONO orderable

Yes — CONO list #127, #120, #126, #109, #118

Each component analyte is separately on the CONO list: 127 TSH, 120 free T4, 126 free T3, 109 reverse T3, 118 TPO antibody, all blood. A urine 'thyroid hormones' variant is also listed as CONO item 165 (urine); the CONO list authorizes each analyte individually, not a bundled 'full panel' product.

Linked conditions

• Hypothyroidism ↗
• "Low T3" / reverse T3 dominance ↗

Counselling script

“Rather than ordering everything at once, I follow the staged approach every thyroid guideline recommends: start with TSH, then add the next test based on what that shows. It's not that these tests are never useful, it's that ordering the whole panel up front tends to create confusing results without actually helping. Let's start with TSH today, and I'll add whatever's needed next based on that.”

Revisit if

• —TSH result comes back abnormal
• —New symptoms suggestive of thyroid dysfunction develop

References

1. [1]Ontario Association of Medical Laboratories (OAML) (2007). Guideline for the Use of Laboratory Tests to Detect Thyroid Dysfunction (CLP 015). linkolder guidelineIn most situations, TSH alone is the appropriate initial test; other thyroid tests follow a confirmed abnormal result
2. [2]National Institute for Health and Care Excellence (NICE) (2019). Thyroid disease: assessment and management (NG145). linkNICE recommends a staged (cascading) approach: TSH alone first, with FT4 and FT3 added based on the TSH result
3. [3]College of Family Physicians of Canada / Choosing Wisely Canada (2026). Family Medicine: Fifteen Tests and Treatments to Question. linkDon't screen for thyroid dysfunction in asymptomatic nonpregnant adults
4. [4]Association of Clinical Scientists (Annals of Clinical & Laboratory Science) (2020). Trust your Endocrinologist – Report and Recommendations on the Ordering of Reverse T3 Testing. linkReverse T3 is not recommended by any professional practice guideline and is frequently ordered inappropriately