title: Hypothyroidism and reversible kidney dysfunction: an essential relationship to recognize.
abstract: OBJECTIVE
  To report 3 cases of reversible hypothyroidism-induced kidney dysfunction and review the interaction between these commonly encountered, yet seemingly disparate, conditions.
  
  
  METHODS
  We describe the clinical course and laboratory and physical findings of 3 patients who presented with kidney dysfunction that improved after initiating thyroid hormone replacement therapy. We also review similar cases in the literature and discuss the pathophysiologic mechanisms.
  
  
  RESULTS
  A 68-year-old male presented with classical signs and symptoms of hypothyroidism, including fatigue, confusion, and gait imbalance. Physical exam showed bradycardia, thyromegaly, slow mentation, and cracked, thin skin; he was found to have decreased kidney function. Second, a 42-year-old previously healthy female presented with bilateral hand swelling and elevated serum creatinine with an otherwise unremarkable physical exam. The third patient was a 72-year-old male with advanced heart failure on amiodarone and stage 3 chronic kidney disease who presented with fatigue, acute kidney injury, and lower extremity edema. In all cases, serum creatinine and thyroid-stimulating hormone (TSH) were elevated at presentation (1.4-3.0 mg/dL and 94.1-184 mIU/L respectively), and free thyroxine (T4) was low (undetectable-0.4 ng/dL). The initiation or increased dose of levothyroxine normalized serum creatinine to baseline within 2 to 10 months.
  
  
  CONCLUSIONS
  Hypothyroidism and kidney dysfunction are both commonly encountered clinical entities, but the interplay between the thyroid gland and kidneys may be infrequently recalled, causing the reversible relationship between these 2 disorders to be missed.
authors: Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota.
authors: Mireille
authors: M
authors: El Ters
authors: The Heart and Vascular Institute, University of Pittsburgh, Pennsylvania.
authors: Sandeep M
authors: SM
authors: Patel
authors: Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota.
authors: Suzanne M
authors: SM
authors: Norby
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007037:Hypothyroidism / Q000150:complications*; D007674:Kidney Diseases / Q000209:etiology*; D008297:Male; D051436:Renal Insufficiency, Chronic / Q000209:etiology