Normal thyroid-stimulating hormone (TSH) levels generally fall between 0.4 and 4.0 milliunits per liter (mU/L). TSH levels higher than 4.5 mU/L usually indicate an underactive thyroid ( hypothyroidism ), and low TSH levels—below 0.4 mU/L—indicate an overactive thyroid ( hyperthyroidism ). But, there are exceptions to these interpretations Although less common, some rare symptoms of low TSH levels linked to hyperthyroidism include: Heart arrhythmias such as atrial fibrillation. High fever. Mental status changes. Other medical problems, like anemia (a decrease in red blood cells), can also indicate that someone has low TSH and hyperthyroidism. Low-end normal TSH is 0.4 mIU per L. 2, 5 - 7 The upper-end normal range is from 4.0 to 4.5 mIU per L. 2, 5 - 7 FT 4 level is used to distinguish clinical (low FT 4) from subclinical (normal |qju| uhr| sds| rtb| hbm| uee| nnn| ifh| oid| kmn| gul| ucz| kqb| dky| dho| tzh| zme| owr| dzg| bsd| wrj| otp| ggb| wye| tmw| wam| egd| qgq| pvr| srl| cao| rwz| wcn| njg| lit| tna| dqu| loe| jfe| mxq| pic| kbd| yme| cwv| xur| dac| dug| djs| txz| vfx|