What does a tsh level 13 mean is it really high, little high ? and what are the future health risks for such a number

Rather high: It is high enough to warrant treatment even if your T4 is normal.Your T3 (liothyronine) should be checked also

Elevated TSH: An elevated TSH level can mean two things-- most commonly that the body is not producing enough thyroid hormone and so the feedback loop is calling for more. The body feels "hypothyroid" which can end up with myriad problems from heart disease to coma if not treated. Much less likely is production of TSH by a tumor in the pituitary or elsewhere, but this is quite rare compared to other hormones produced by the pituitary.