TSHI

Quantifies pituitary TSH sensitivity to free T4.
Also known as:
TSH Index
.
Enter values
 
Value
Unit
TSH
fT4

TSHI ranges

According to Jostel et al. (2009), TSHI should be between 1.35 and 4.05:
1.35
4.05
Central hypothyroidism was associated with TSHI below 1.35:
1.35
Risk Scale
Optimal range for TSHI appears to be between 1.69 and 3.71:
0
1.35
1.69
3.71
4.05
5
Why this optimal range?
There is not enough evidence to define clear cut-offs for TSHI. Ranges in red are: ±2xSD from the mean, ranges in yellow are ±1.5-2xSD from the mean.

Quantifies pituitary TSH sensitivity to free T4.

There is not enough evidence to define clear cut-offs for TSHI. Ranges in red are: ±2xSD from the mean, ranges in yellow are ±1.5-2xSD from the mean.

TSHI interpretation

For low

Low TSHI means that TSH is lower than expected for the given FT4, reflecting apparent pituitary over-sensitivity or impaired TSH secretion. Very low values may support a diagnosis of central (secondary/tertiary) hypothyroidism.

For high

High TSHI indicates TSH is higher than expected for the given FT4, most commonly seen in subclinical hypothyroidism or reduced apparent pituitary sensitivity.

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Zsolt Szabo
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