What do the H and L flags mean on a Quest result?

H means the value is above Quest's reference range and L means it is below it. A flag only indicates the value falls outside the lab's reference interval — it is not a diagnosis. Ranges vary by lab and by your individual situation, so a flagged value is a prompt to discuss with your doctor, not a conclusion.

Why are my Quest reference ranges different from my old lab's?

Each lab sets its own reference ranges based on its testing method and population, so Quest, LabCorp, and hospital labs often list slightly different intervals — and sometimes different units. That is why comparing a raw number across labs can be misleading; what matters is the trend with units normalized.

Can I track my Quest thyroid results over time?

Yes. LabLens reads your Quest thyroid PDF and charts TSH, Free T4, Free T3, and antibodies across every test, so you see the trend instead of one isolated result. It is descriptive only and never diagnoses or recommends dosing, and everything stays on your iPhone.

How to read your Quest Diagnostics thyroid results

Q: Where do I find my thyroid results on a Quest report?

On a Quest Diagnostics report, each test is listed in a table with the test name (e.g. TSH), your result value, the units, the reference range, and a flag column. Thyroid markers are usually grouped together; TSH is the most common. You can view and download the PDF from the MyQuest patient portal or app.

Updated June 10, 2026 · ~6 min read

You open the MyQuest app, see a thyroid result, and your eyes go straight to the flag — is there an "H" next to it? A Quest Diagnostics report packs a lot into a small table, and once you know how to read it, the whole thing gets a lot calmer. Here's a plain-English walkthrough of a Quest thyroid panel: what each column means, where your thyroid markers live, and why one report rarely tells the full story.

What's on a Quest thyroid report

Every Quest result is laid out as a table. For each test you'll see the same columns:

Test name — e.g. TSH, Thyroxine (T4) Free, Triiodothyronine (T3) Free, Thyroid Peroxidase (TPO) Antibodies.
Result — your value for this draw.
Units — the measurement unit (e.g. mIU/L for TSH, ng/dL for Free T4).
Reference range — the interval Quest considers typical for that test.
Flag — blank if you're inside the range, or H / L if you're above or below it.

Thyroid markers are usually grouped together on the report. TSH is the one almost every panel includes; Free T4, Free T3, and antibodies appear depending on what your doctor ordered.

The thyroid markers, briefly

Here's what each line is measuring, in one sentence. For the fuller picture, see our guide on how to read your thyroid lab results over time.

TSH — the pituitary's signal to the thyroid; the most commonly tracked thyroid number.
Free T4 — the available form of the main thyroid hormone in circulation.
Free T3 — the more active hormone, ordered less routinely.
TPO antibodies — an autoimmune marker associated with Hashimoto's; levels tend to fluctuate.

What the H and L flags actually mean

An H means your value sits above Quest's reference range; an L means below it. That's all a flag is — a note that the number falls outside the lab's interval. It is not a diagnosis, and a flagged value isn't automatically a problem any more than an unflagged one is automatically fine. Reference ranges are statistical, set by the lab, and your doctor reads them against your individual history. Treat a flag as a reason to ask, not an answer.

Why your Quest range may differ from another lab's

Quest sets its own reference ranges based on its testing methods and population. So if you've also been tested at LabCorp or a hospital lab, you may notice the ranges — and sometimes the units — don't match. This is normal, and it's exactly why comparing a raw number from Quest to a raw number from another lab can mislead you. What you actually want is the trend, with units normalized so a lab switch doesn't masquerade as a health change. (More on consolidating providers: how to keep every lab in one place.)

Why one Quest report isn't the whole story

A single result tells you where you are on one day. With thyroid conditions, the meaningful signal is almost always the direction of travel across many draws — a TSH slowly drifting, or settling after a change your doctor made. Quest's portal shows you results one at a time; the pattern across them is what's worth keeping.

Getting your Quest PDF

You can view and download your results from the MyQuest patient portal or app — open the result, then use the download/share option to save the PDF. That PDF is all you need to start building a trend you control, rather than logging back in every time you want to compare.

Turn your Quest PDFs into one thyroid trend

Drop your Quest thyroid PDF into LabLens and it charts TSH, Free T4, Free T3, and your antibodies over time, explaining each value in plain English. It recognizes Quest, LabCorp, and MyChart formats. Descriptive only: it never diagnoses or recommends dosing. Everything stays on your iPhone — no server, no analytics.

Frequently asked questions

Where do I find my thyroid results on a Quest report?

Each test sits in a table with its name, your result, units, reference range, and a flag column; thyroid markers are grouped together, with TSH the most common. View and download the PDF from the MyQuest portal or app.

What do the H and L flags mean?

H is above Quest's reference range, L is below it. A flag only marks a value outside the lab's interval — it isn't a diagnosis. Discuss flagged values with your doctor.

Why are my Quest ranges different from another lab's?

Each lab sets its own ranges (and sometimes units) by method and population, so Quest and LabCorp often differ. That's why the normalized trend matters more than a raw cross-lab comparison.

Can I track my Quest results over time?

Yes — LabLens reads your Quest thyroid PDF and charts each marker across every test. It's descriptive only and keeps everything on your iPhone. See the Privacy Policy.

For information only. This guide is educational and descriptive — it does not diagnose, recommend dosing, or replace medical advice. Discuss any changes with your endocrinologist.