Redox unbalance in the hyperthyroid cat
Forty cats with untreated hyperthyroidism, 45 chronically ill cats with non-thyroidal illness, and 39 healthy cats were evaluated. All cats were screened for redox status markers. Determinable reactive oxygen metabolites (d-ROMs) were used as oxidative stress markers. Antioxidant status was determined using the OXY-Adsorbent test to quantify the plasma barrier to oxidation. The Oxidative Stress index (OSi) was calculated as the ratio of d-ROMs and OXY-Adsorbent test values.
The Determinable reactive oxygen metabolites of untreated hyperthyroidism were significantly higher than those of the healthy cats. The OXY-Adsorbent test results in cats with untreated hyperthyroidism were significantly lower than those in healthy cats and chronically ill cats. Moreover, the Oxidative Stress index value in the cats with untreated hyperthyroidism was significantly higher than that of the healthy cats.
The results suggest that feline hyperthyroidism is associated with redox unbalance as it is also described in humans with hyperthyroidism. Free radical production is increased in hyperthyroid cats and their antioxidant depletion seems to be more severe than in cats with non-thyroidal illnesses. Our results support the rationale for a clinical trial investigating the potential positive effects of antioxidant supplementation to cats with hyperthyroidism.