The normal value of Free T4 hormone in the blood varies by age. For healthy adults, a typical reference range is 0.9-1.7 ng/dL. Values below this range may indicate an underactive thyroid (hypothyroidism), while elevated levels could suggest an overactive thyroid (hyperthyroidism) or other thyroid dysfunctions.

Age-specific reference ranges are as follows:
* 0-5 years: 0.8-2.8 ng/dL
* 6-15 years: 0.8-2.1 ng/dL
* 16-17 years (Male): 0.8-2.8 ng/dL
* 16-17 years (Female): 0.8-1.5 ng/dL
* 18 years and above: 0.9-1.7 ng/dL

It is important to note that laboratory reference ranges can slightly vary, and results should always be interpreted by a healthcare professional.