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. Author manuscript; available in PMC: 2018 Apr 1.
Published in final edited form as: Clin Biochem. 2016 Nov 25;50(6):318–322. doi: 10.1016/j.clinbiochem.2016.11.022

Figure 1.

Figure 1

Comparison of free and total thyroid hormones performed by immunoassay (IA) and liquid chromatography-tandem mass spectrometry (LC-MSMS).

A) Free 3,5,5'-triidothyronine (FT3) performed by IA and LC-MSMS in pg/mL. Horizontal lines represent the reference interval for FT3 measurement by LC-MSMS (2.0 – 6.0 pg/mL) and vertical lines the reference interval by IA (2.0 – 4.4 pg/mL). y = 0.97*x + 0.79; spearman r = 0.37, p = 0.01.

B) Free thyroxine (FT4) performed by IA and LC-MSMS in ng/dL. Horizontal lines represent the reference interval for FT4 measurement by LC-MSMS (1.3 – 2.4 ng/dL) and vertical lines the reference interval by IA (0.9 – 1.7 ng/dL). y = 2.0*x – 0.098, spearman r = 0.53, p = 0.0001

C) Total 3,5,5'-triidothyronine (TT3) performed by IA and LC-MSMS in ng/dL. Horizontal lines represent the reference interval for TT3 measurement by LC-MSMS (80 – 177 ng/dL) and vertical lines the reference interval by IA (80 – 200 ng/dL). y = 0.85*x – 13.51, spearman r = 0.83, p < 0.0001.

D) Total thyroxine (TT4) performed by IA and LC-MSMS in µg/dL. Horizontal lines represent the reference interval for TT4 measurement by LC-MSMS (4.9 – 10.5 µg/dL) and vertical lines the reference interval by IA (5.0 – 10.9 µg/dL). y = 0.81*x + 2.06, spearman r = 0.86, p < 0.0001.