PTFQI-FT3

Quantifies pituitary TSH sensitivity to free T3 using standardized z-scores, improving stability at extreme hormone values.
Enter values
 
Value
Unit
TSH
fT3

PTFQI-FT3 ranges

According to Kratzsch et al. (2005), PTFQI-FT3 should be between -0.7 and 0.7:
-0.7
0.7
Risk Scale
Optimal range for PTFQI-FT3 appears to be between -0.4 and 0.4:
-1
-0.7
-0.4
0.4
0.7
1
Why this optimal range?
Ranges are based on standard deviations from the mean. Values in red (±2 SD) indicate significant deviation from expected pituitary-thyroid feedback; values in yellow (±1-2 SD) indicate moderate deviation.

Quantifies pituitary TSH sensitivity to free T3 using standardized z-scores, improving stability at extreme hormone values.

There is only one study Kratzsch et al. (2005) that used strict criteria for healthy thyroid function (NACB criteria + normal ultrasound) so the parameters to calculate PTFQI-FT3 are used from this study.

PTFQI-FT3 interpretation

For low

Low PTFQI-FT3 means that TSH is lower than expected for the given FT3, reflecting apparent pituitary over-sensitivity or impaired TSH secretion. Very low values may support a diagnosis of central (secondary/tertiary) hypothyroidism.

For high

High PTFQI-FT3 indicates TSH is higher than expected for the given FT3, most commonly seen in subclinical hypothyroidism or reduced apparent pituitary sensitivity.

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Zsolt Szabo
Zsolt Szabo
Precision Health Consultant for Longevity Clinics, Biohacker, and Software Engineer

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