Background: Thyroid gland disorders represent one of the commonest endocrine manifestations of chronic hepatitis C (HCV).
Objective: This study was performed to evaluate thyroid hormones profile in patients with chronic hepatitis C and its relation to severity of liver damage in the presence or absence of diabetes mellitus.
Patients and methods: This study was performed on sixty patients with liver cirrhosis due to hepatitis C virus with or without diabetes mellitus. The patients were divided into three equal groups according to Child-Pough score as following: Group A, group B and group C. All patients were subjected to medical history, clinical examination and laboratory investigations including liver functions tests, renal function tests, complete blood picture (CBC), viral markers for hepatitis, hepatitis C virus antibody (HCV-Ab) and hepatitis B virus antigen (HBs-Ag), polymerase chain reaction (PCR), fasting blood sugar (FBS), postprandial blood sugar(PPBS) hemoglobin A1 C (HbA1c),  tetra-iodothyronin (T4), tri-iodothyronin( FT3), thyroid stimulating hormone (TSH) and abdominal ultrasound.
Results: Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood platelet and FT3 were significantly lower in group C than group B and group A, while serum levels of bilirubin andprothrombin time(PT) were significantly higher in group C than B and A. Serum levels of FT3 was positively correlated with serum albumin and negatively correlated with serum bilirubin and PT. There were no significant changes in the serum levels of FT3, FT4 and TSH between diabetic and non-diabetic patients. On the other hand, serum levels of ALT, AST, and albumin  significantly elevated in diabetic versus non-diabetic patients.
Conclusions: A highly significant reduction of serum FT3 in liver cirrhosis with normal serum FT4 and TSH levels was attributive to decreased deiodination of T4 to T3. Decreased serum FT3 level correlated with the severity of liver disease, and may be helpful in assessing the course and diagnosis of liver cirrhosis. Also, serum FT3 hormone level could be used as a marker for grading and assessment of the severity of hepatic dysfunctions.