Hypothyroidism, defined by elevated thyrotropin (TSH) levels, is a common endocrine complication of chronic kidney disease that has been associated with impaired quality of life and cardiovascular complications. While levothyroxine is one of the most frequently prescribed medications in chronic kidney disease patients, little is known about its efficacy and safety in this population. This study will investigate 1) whether levothyroxine adequately lowers thyrotropin (TSH) levels to therapeutic target ranges, and 2) if thyroid hormone replacement improves quality of life and cardiovascular markers, without leading to wasting in dialysis patients.