I don't know if we can just assume that missing lunula is normal. For example, in my case, I have had lethargy, fatigue symptoms much before my hypothyroid was diagnosed. Probably, there is an interplay between deficiency and thyroid, probably there is an association, deficiency maybe a causal factor also. We don't know that.
Unfortunately, even in yearly health check ups, standard procedure is to check your regular blood work, BP, Sugar, Eyes, Heart etc.