LABOKLIN Service ID: 495
rT3 is an inactive metabolite of thyroxine (T4). If sufficient or large amounts of T4 are present, more rT3 is produced, while the rT3 concentration decreases when little T4 is available.
| Material | serum 0.5 ml |
| Method | LCMS |
| Species list | Dog, cat |
| Duration | 2–3 working days |
| Remark | Dog:- This parameter is primarily used to help differentiate between nonthyroidal illness syndrome (NTI, formerly known as euthyroid sick syndrome) and hypothyroidism.
- It is expected that rT3 is reduced in hypothyroidism, whereas it is not reduced in NTI.
Cat:- rT3 is significantly elevated in cats with hyperthyroidism.
- In cases of suspected hyperthyroidism where T4 is not or only marginally elevated, rT3 can provide additional information. In hyperthyroidism, it is usually significantly increased.
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