Analysis index

1 ml serum

Adults: 1,7 – 3,7 pg/ml

Children:

Up to 1 year of age:      2,32 pg/ml – 4,84 pg/ml

Up to 12 years of age:   2,79 pg/ml – 4,42 pg/ml

Girls:

Up to 15 years of age:   2,50 pg/ml – 3,95 pg/ml

Up to 19 years of age:   2,31 pg/ml – 3,71 pg/ml

Boys:

Up to 15 years of age:   2,89 pg/ml – 4,33 pg/ml

Up to 19 years of age:   2,25 pg/ml – 3,85 pg/ml

Only utilizable in connection with the evaluation of TSH and fT4 for the assessment of the thyroid function

In rare cases, an isolated T3-hyperthyroidism can occur. However, an fT3 increase can also be present initially in the early stages of a hyperthyroidism in the context of an autoimmune thyropathy. Low fT3 levels may also point towards a low T3-syndrome. This occurs in serious general illnesses and is a non-therapy dependent adaptation process of metabolism. A conversion to a low T3-low T4-syndrome is classed as unfavorable for prognosis. T3 is formed primarily in the peripheral tissue by deiodization from T4. Whether fT3 levels measured in the peripheral blood reliably reflect the actual concentration in the organs (especially the brain), is currently the subject of research. In case of hypothyroidism, partially elevated fT3 levels may be measured in the early stages as a sign of a reactive conversion increase, and are therefore not meaningful.