Effect of Levothyroxine on Serum Adiponectin, Insulin Resistance and Cardiovascular Risk in Patients With Hypothyroidism
Condition: Hypothyroidism
MeSH terms: Insulin Resistance; Hypothyroidism
Study type: Observational

Summary: 
      The aim of this study is to evaluate plasma adiponectin level, insulin resistance,
      cardiovascular risk and their correlation (if any) in patients with hypothyroidism and also
      to investigate the effect of levothyroxine on these parameters. The study may explore the
      lacunae in present treatment protocol and can suggest the possibilities of add-on therapies
      for a better management.
    

Detailed description: 
      Hypothyroidism is associated with premature atherosclerosis and increased prevalence of
      coronary artery diseases. Long-term hypothyroidism is associated with severe cardiovascular
      manifestations including reduced intravascular volume, increased systemic vascular
      resistance, and hypertension. Hypothyroidism is one of the main causes of secondary
      dyslipidemia. The classic manifestations of hypothyroidism are raised VLDL, LDL and apo A.
      The increase in cardiovascular risk is not only due to dyslipidemia, but also to hemodynamic
      changes, endothelial dysfunction, hormonal and metabolic changes. Insulin resistance and the
      metabolic syndrome are important cardiovascular risk factors as insulin-resistant individuals
      with raised TSH have higher LDL concentrations.

      Among the various markers associated with obesity and insulin resistance, of particular
      importance is adiponectin which is inversely related to the degree of adiposity, increases
      insulin sensitivity, and has antiatherogenic and anti-inflammatory properties, hence may be
      cardioprotective. Hypoadiponectinaemia is associated with obesity, insulin resistance and
      type II diabetes, as well as atherosclerosis, hypertension and coronary artery disease.

      Treating hypothyroidism with levothyroxine has an antioxidant and cholesterol reducing
      effect, and thus already has proven beneficial impact on cardiovascular function, blood
      pressure and lipid profile. But the association of adiponectin and insulin resistance in
      hypothyroid state and future cardiovascular risk is still not clear because there are few
      published studies in this domain and result of some the studies are contradictory. The aim of
      this study is to evaluate plasma adiponectin level, insulin resistance, cardiovascular risk
      and their correlation (if any) in patients with hypothyroidism and also to investigate the
      effect of levothyroxine on these parameters.
    

Intervention name(s): Levothyroxine
Intervention type(s): Drug
Intervention description(s): At first visit, after taking detailed history including baseline symptomatology, clinical evaluation, and laboratory investigation, treatment will be started with levothyroxine (50 microgram/day). The dosage of levothyroxine (LT4) will be adjusted (at 4th and 8th week) in an attempt to keep the serum FT4 and TSH concentrations within the normal range. After 12 weeks, all the patients will be followed up, clinical and laboratory tests will be repeated.
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        The study will be conducted on 50 patients of hypothyroidism attending the outpatient
        department of General Medicine, All India Institute of Medical Sciences, Bhubaneswar.
        Another 50 euthyroid, age-, sex-matched subjects will be recruited as control.
      
Keywords: Hypothyroidism; Serum adiponectin; hsCRP; Homeostatic Model Assessment (HOMA-IR); Quantitative Insulin Sensitivity Check Index (QUICKI); Cardiovascular risk assessment scoring (Framingham scoring); Levothyroxin