It's Not Lupus This Time! A Case of Worsening Hypothyroidism in a Patient With Nephrotic Syndrome

Nephrotic syndrome can result in worsening of existing hypothyroidism in patients requiring thyroid hormone supplementation. The urinary loss of thyroxine-binding globulin, as well as increased gut edema, likely lead to reduced absorption and retention of exogenous thyroid hormone. Here, we present a case of a patient with Hashimoto's thyroiditis, previously well-controlled on levothyroxine, who developed symptomatic hypothyroidism as a result of newly diagnosed nephrotic syndrome, whose symptoms improved with transition to an alternative formulation of levothyroxine and treatment of her underlying nephrotic syndrome. It is important to consider nephrotic syndrome as a cause of worsening hypothyroidism in a patient on a fixed dose of levothyroxine given the potential morbidity associated with a missed diagnosis and often need for escalation of dosage. There is no standardized therapy for hypothyroidism exacerbated by nephrotic syndrome, but liquid or gel formulations of levothyroxine may be more effective in patients with absorption problems.