title: Nephrotic Syndrome Increases the Need for Levothyroxine Replacement in Patients with Hypothyroidism.
abstract: BACKGROUND
  Nephrotic syndrome is a known cause of hypothyroidism; however, its effect on replacement doses of L-thyroxine in patients with primary hypothyroidism is not systematically studied.
  
  
  OBJECTIVE
  The aim of the present study was to evaluate the effect of newly diagnosed nephrotic syndrome on the dose of L-thyroxine replacement in previously diagnosed patients with primary hypothyroidism who were on full, stable dose of L-thyroxine replacement for at least one year.
  
  
  METHODS
  Patients with previously diagnosed primary hypothyroidism on stable and full (≥1.6μg/day) replacement dose of L-thyroxine for at least one year who developed newly diagnosed nephrotic syndrome were included in the study. Patients were evaluated with thyroid function tests at diagnosis and every 2-3months. Replacement doses of L-thyroxine were titrated by a single endocrinologist based on serum Thyroid Stimulating Hormone (TSH) level.
  
  
  RESULTS
  The study included nine patients with mean age of 42.77±9.61years. There was significant increase in TSH at diagnosis of nephrotic syndrome (8.16±2.82μIU/ml) when compared to the immediate past visit (2.08±0.7μIU/ml) and needed 17.6% increase in the replacement dose of L-thyroxine. At last follow-up four patients had remission of nephrotic syndrome and in them thyroid function tests improved with reduction in replacement dose of L-thyroxine by 15% whereas patients who did not achieve remission had required further increase in L-thyroxine dose by 19.1%.
  
  
  CONCLUSIONS
  Development of nephrotic syndrome significantly increases the need for L-thyroxine replacement dose in previously diagnosed primary hypothyroidism patients on full stable dose of L-thyroxine replacement.
authors.affiliation: Associate Professor, Department of Nephrology, Vydehi Institute of Medical Sciences and Research Center , Bengaluru, Karnataka, India .
authors.forename: Hareeshababu
authors.initials: H
authors.lastname: Karethimmaiah
authors.affiliation: Associate Professor, Department of Endocrinology, Vydehi Institute of Medical Sciences and Research Center , Bengaluru, Karnataka, India .
authors.forename: Vijaya
authors.initials: V
authors.lastname: Sarathi
keywords: Primary hypothyroidism; Proteinuria; Urinary loss of thyroxine