Test ranges

[veryangirl44]

Hi all this is probably a silly question but I'm going to ask anyway ha ha. Can anyone please tell me how the test ranges are set for thyroid tests and also how comes they differ in different places? Many thanks in advance

[diogenes Remembering]

Though test ranges for a given test product have ranges set by the manufacturer of the testing machine, usually hospital labs think they are inadequate and individually set up their own. Often this is done rather haphazardly and it can be affected by the choice and number of subjects to set up the range. In addition, different manufacturers often have basically different results for the same tests. For example, TSH can be up to 10-15% different, manufacturer-to-manufacturer, FT4 25%, and FT3 (heaven help us) up to 40%. This is a scandal that has lasted over 35 years, and only now is attention being drawn to this, and work done to reconcile the tests. BUT NOT FT3 - that is left in the cold because present medical thinking only gives it a minor role so it's thought not worth correcting. TSH is being dealt with (surprise,surprise) but for FT4, the manufacturers are "discussing whether to do anything about it or not". The whole business has come about through a lethal combination of regulatory failure, manufacturers' ignorance and scientific mediocrity, and end-user complacency.

[veryangirl44 in reply to diogenes]

Thank you for your quick reply. I'm feeling really ignorant to it all. Are the tests taken from a number of healthy people and how their body's work? I must sound so silly.

[diogenes Remembering in reply to veryangirl44]

Usually thyroid tests have a reference range derived from a mixture of perfectly healthy lab staff and from patients referred to a doctor for a minor illness which turned out not to be thyroid based. Often the numbers used are small - say 100 - to get the range. This means the range is rather fuzzily derived - 500 would give a more firmly based result. It also assumes that the minor illness didn't have a small effect on the results - usually this is true, but not always and NOT for FT3, which should always be referenced from healthy people.

[veryangirl44 in reply to diogenes]

It's crazy how we feel is based on a number and our symptoms not listened to. With so many more people suffering more than ever now the system really does need a shake up. X

[Clutter]

Veryangirl44,

The manufacturers of the analysis machines stipulate the machine range to be used in conjunction with the lab's local population mean average result to determine the reference range that particular lab will use. This is why ref ranges are not universal and results can only be interpreted using the ref range of the lab which analysed your results.

labtestsonline.org.uk/under...

[veryangirl44 in reply to Clutter]

Thank you it answer my question straight away.