Reference Range Update: Thyroid Tests

In order to prevent Biotin interferences several endocrine oriented tests have been updated, see test information below.

In addition, reference ranges have been standardized in preparation for the Spectrum Health Lakeland integration with Spectrum Health West Michigan. New vendor recommended reference ranges were validated internally for the new versions of the test. Pediatric ranges will not be affected. New adult ranges will be as follows:

Test Name	New Reference Range starting 7/18/2022	Former Reference Range
Free T3 (Triiodothyronine)	2.0 – 4.4 pg/mL	2.2 – 3.9 pg/mL
Total T3 (Triiodothyronine)	20 Years and up: 80 – 200 ng/dL	20 Years and up: 80 – 220 ng/dL
Total T4 (Thyroxine)	4.5 – 11.7 mcg/dL	5.1 – 14.1 mcg/dL
FSH Level:	Male: Adult: 1.5 – 12.4 mIU/mL Female: Follicular: 3.5 – 12.5 mIU/mL Ovulatory: 4.7 – 21.5 mIU/mL Luteal: 1.7 – 7.7 mIU/mL Post-Menopausal: 25.8 – 137.8 mIU/mL	Male: Adult: 2.0 – 10.0 mIU/mL Female: Follicular: 3.0 – 12.0 mIU/mL Ovulatory: 8.0 – 22.0 mIU/mL Luteal: 2.0 – 10.0 mIU/mL Post-Menopausal: 17.0 – 108.0 mIU/mL