The Log/Linear relationship of serum TSH/FT4 was analyzed in 245 patients of hypo-and hyperthyroidism including subclinical cases.The serum TSH level was much lower（i.e.<0.3mU/L）and serum FT4 level was within normal limits in patients with subclinical hyperthyroidism.The serum TSH level elevated over 5mU/L and serum FT4 level was within normal limit in patients with subclinical hypothyroidism.The TSH/FT4 Log/Linear relationship mapping can clearly reflect the area distribution of various functional status of different thyroid diseases.Besides

the characteristic manifestation of the subclinical thyroid diseases demonstrated that any subtle changes in serum FT4 level induced the amplified response in serum TSH level.