Using insurance and going through a doctor it can be difficult (understatement!) to find out what something will cost ahead of time. Your insurance may charge you $150 for a sick visit to the doctor, and the doctor may tell you there is no charge for the test, but unless you ask the right questions you won't find out that they are just talking about their part of taking the blood sample and ordering the test, they won't volunteer that there may be third party lab charges, and they and their office staff will have no idea what those charges might be. It can take a lot of time to chase down all the parties involved - your insurance company, the doctor, the lab, for other things maybe a radialogist, an anaesthesiologist, and/or facility charges at a hospital or clinic, medications from pharmacist, and so on, trying to find out what the total bill might be, and there are no guarantees, any of them can tell you one price and bill something different, it might depend on which billing codes are used for each procedure, and you may not get all the bills for months. Doctors have you sign a paper saying you will pay for anything deemed medically necessary, and these third parties will threaten to send you to collections based on that, if you complain. Typical insurance plans have a yearly deductable of several thousand dollars, applicable to non-preventive care, with the idea being to incentivize people to pay attention to the costs for routine care (there's also an out of pocket maximum, perhaps $10-15k per year). But the costs are obfuscated. It's not a free market system, it's a scam, a jobs program for health care administrators (3200% increase from 1975 to 2010) [1].
[0] https://www.testing.com/tests/thyroid-stimulating-hormone-ts...
[1] https://www.athenahealth.com/knowledge-hub/practice-manageme...