Free T4 test cost in Ontario, CA — inpatient
In Ontario, CA, 1 hospital lists a cash price for free T4 (free thyroxine) thyroid blood test as an inpatient: from $68.12 to $68.12, with a median of $68.12. Across California, the median is $68.12 at 104 hospitals.
Cash prices at 1 facility for code 84439, as an inpatient (admitted to hospital) . Collected Sep 23, 2026; the hospital files themselves were last updated between — and —.
Hospitals, cheapest first
| Hospital | Cash price | List price | Insurers pay | Off list | File date |
|---|---|---|---|---|---|
| Kaiser Foundation Hospital - Ontario Ontario, CA ASSAY OF FREE THYROXINE | $68.12 | $131.00 | $7.00–$20.00 | 48% | — source file |
Inpatient: lowest $68.12, median $68.12, highest $68.12.
As an outpatient, the same code is billed by 1 facility here, median $68.12 — that is the price to compare if you are not being admitted.
Cash or insurance?
At the one hospital here that publishes insurer rates for this code, the cash price is not below the highest rate a health plan has negotiated. If you have insurance but have not met your deductible, you usually pay your plan's negotiated rate, which falls somewhere in the "Insurers pay" column. Paying cash can cost less, but a cash payment usually does not count toward your deductible. Ask the hospital for both numbers before you book.
What it is
A free T4 test measures thyroxine that is not bound to proteins, the active form of the main thyroid hormone. It is usually ordered with or after a TSH test to check for an underactive or overactive thyroid and to adjust thyroid medicine.
What the price covers
The price usually covers the free T4 test only. The blood draw and the TSH test (84443) are billed separately.