**9. Conclusions**

Increased serum concentrations of transthyretin are typically associated with chronic renal failure, presumably due to the decreased tubular uptake and degradation of RBP [82]. Cano [83] stated also that chronic renal failure may result in an increase of serum TTR concentrations, but these elevated TTR values during renal insufficiency are secondary to the lack of RBP degradation in renal tubules and to the subsequent increase in TTR. The concentrations of TTR may rise also during corticosteroid therapy and administration of anabolic steroids, as well as in patients using anti-inflammatory agents [6, 84]. Young et al. [85] found increased concentrations of TTR in ill-surgical patients receiving anabolic steroids, which may enhance amino acid and water uptake by tissues and increase the utilization of fat. Increased TTR concentrations may be seen in acute alcohol intoxication, caused by the leakage of proteins from damaged hepatic cells [86]. Transthyretin was shown to be upregulated also in Hodgkin´s

Several studies evaluated the significance of TTR as a prognostic biomarker and suggested that low concentrations may be associated with poor prognosis [88, 89]. Transthyretin was found as a prognostic factor for treatment outcomes and/or nutritional status of colon, oesophagus, ovarian and lung cancers [90–92]. In these studies, the concentrations of TTR correlated with response to treatment and clinical outcomes. Ho et al. [93] reported that low values of TTR may serve as prognostic factor for overall survival in cancer patients. However, the interpretation of its values in patients with systemic inflammatory response may be challenging. In these conditions, further clinical assessments and laboratory assays may be helpful, including markers of inflammation such as C-reactive protein, erythrocyte sedimentation rate or white

According to Cheng et al. [94], TTR has also been identified as a significant predictor of clinical outcomes after surgical intervention. Therefore, it may be used as part of the blood screening completed before surgery to determine pre-surgery health. Low TTR values before surgery may be associated with an increased risk of complications, including infections or pneumonia. Devakonda et al. [88] reported that surgery patients with low preoperative TTR values had significantly longer hospital duration of stay and longer intensive care unit duration of stay. Moreover, low concentrations of transthyretin were associated with higher rates of infectious complications, mortality and other surgical

Despite the physiological importance of transthyretin in health and as disease marker, there are only a few studies analysing its usefulness in the clinical and laboratory diagnosis of diseases in animals. Studies performed in dogs suggested that not only quantitative but also qualitative differences exist between human and canine TTR [97]. Transthyretin from dog plasma was of lower molecular mass compared to human TTR in samples subjected to sodium

**8. The usefulness of transthyretin in veterinary medicine**

lymphoma and pancreatic cancer [11, 87].

**7.3. Prognostic indicator**

58 Pathophysiology - Altered Physiological States

blood cell number.

complications [95, 96].

Presented data suggest that transthyretin may contribute to the evaluation of health state and diagnosis of some diseases also in animals. Changes in serum concentrations of TTR may be indicative of inadequate nutrient intake and may serve as an additional diagnostic tool for clinicians in the evaluation of some pathological conditions. It may be used as an integral part of the overall health assessment or in hospitalized animals to evaluate their nutritional status during the treatment and recovery. Low serum TTR concentrations may be considered a sign of increased risk of malnutrition, requiring further nutritional assessment.

#### **Acknowledgement**

This work was supported by Scientific Grant Agency of Ministry of Education SR Nos. 1/0154/15 and 1/0486/17.
