Is it maybe talking about rate of change of TSH risk is greater at smaller TSH?

They said that 'putting it into perspective, the model predicts that the odds of thyroid cancer is 3x greater in a patient with a TSH of 4 mU/L compared with TSH of 0. Within the normal range, the model predicts a doubling of odds of thyroid cancer between a TSH of 0.65-4 mU/L; from a normal range to an elevated TSH there is a doubling of odds of thyroid cancer between a serum TSH of 2.2 and 7 mU/L.