Rising TSH/weight gain

Hi

My 18 yr old niece has been gaining weight quickly and recently started experiencing dizziness. Her ENT mentioned getting her thyroid tested but she has had it tested and TSH and T4 in normal range. However, when you look back over the past few years, her TSH has been steadily rising. Could it still be hypo if within normal range? It is over 4.

Thanks so much.

I would get her FT3 and FT4 tested along with the TSH