IL-6 and TNFa downregulate D1 and suppress TSH, are negatively correlated with fT3, and are positively correlated with rT3. NF-κB also inhibits D1, and decreases the expression of Thyroid receptors α and β. IFNy inhibits thyroid and Tg release, and also inhibits the upregulation of TSH receptors. Thyroid hormone receptors
In chronic liver and renal (kidney) failure,  increased THR expression occurs. In contrast, in acute illness such as sepsis and trauma,  decreased THR expression occurs. Thyroid hormone transporters
During NTIS,  alterations arise in the concentrations of thyroid hormone transporters such as MCT8 and MCT10, although whether the levels are increased or decreased depends on the study. The altered concentrations are thought to be a result of NTIS, rather than a cause; a study in rabbits showed that administering thyroid hormones normalized transporter expression. Binding proteins
Decreased thyroxine-binding globulin (TBG) occurs following bypass surgery, and in chronic illness, a less effective form of TBG with lower affinity for thyroxine is synthesized. Reduced quantities of bound thyroid result, leading to decreased total thyroid measurements. Decreases in total thyroid may be more severe than alternations in free hormone levels. Drugs
Dopamine and corticosteroids, commonly given in the hospital setting, can suppress TSH and suppress conversion of T4 to T3. Other drugs such as estrogen, contraceptives, salicylates, and phenytoin can alter the binding of TBG to TH, resulting in different TH concentrations. Additionally, lithium disrupts thyroid function, and thyromimetic endocrine disrupters may downregulate the HPT axis. Fasting
Fasting is a common response in inflammation and critical illness.
Magnetic resonance imaging (MRI) can determine the extent of tendon degeneration, and may show differential diagnoses such as bursitis. Prevention
Performing consistent physical activity will improve the elasticity and strength of the tendon, which will assist in resisting the forces that are applied.While stretching before beginning an exercise session is often recommended evidence to support this practice is limited. Prevention of recurrence includes following appropriate exercise habits and wearing low-heeled shoes. In the case of incorrect foot alignment, orthotics can be used to properly position the feet. Footwear that is specialized to provide shock-absorption can be utilized to defend the longevity of the tendon. Achilles tendon injuries can be the result of exceeding the tendons capabilities for loading, therefore it is important to gradually adapt to exercise if someone is inexperienced, sedentary, or is an athlete who is not progressing at a steady rate.Eccentric strengthening exercises of the gastrocnemius and soleus muscles are utilized to improve the tensile strength of the tendon and lengthen the musculotendinous junction, decreasing the amount of strain experienced with ankle joint movements. This eccentric training method is especially important for individuals with chronic Achilles tendinosis which is classified as the degeneration of collagen fibers. These involve repetitions of slowly lowering the body while standing on the affected leg, using the opposite arm and foot to assist in repeating the cycle, and starting with the heel in a hyperextended position.