Indirect Methods for Reference Intervals Based on Current Data

Grossi et al. (1) recently reported an interesting project that used a sophisticated algorithm for the formulation of reference intervals based on ∼15 000 000 records related to 197 350 individuals. We noted an important difference between their reference interval calculated for thyrotropin (TSH) based on results obtained with the Architect (Abbott) analyzer in women (0.28–4.45 mIU/L) and that recently reported by Kratsch et al. (2). Kratsch et al. selected a group of 870 blood donors with negative thyroid ultrasonography and thyroid autoantibodies, as recommended by criteria of the National Academy of Clinical Biochemistry, and found a reference interval of 0.4–3.77 mIU/L (2). The optimal serum TSH reference interval is strongly debated, and a lowering of the …