NCREASED LEVOTHYROXINE REQUIREMENT IN A PATIENT WITH NEPHROTIC SYNDROME

Abstract

INTRODUCTION/BACKGROUND
In hypothyroid patients, there are no studies that exemplify the need for levothyroxine adjustment in patients with coexisting nephrotic syndrome.

CASE
This case report highlights the degree of levothyroxine adjustment that may be required. A 36-year-old Malay male with post-radioioidine hypothyroidism presented in October 2022 with bilateral lower limb swelling, abdominal distention and a 10-kg weight gain over the preceding 3 months. He received RAI twice (October 2020 and February 2021) for relapsed Graves’ disease. He had been on a levothyroxine replacement dose of 700 µg/week (1.12 µg/kg/day). Tests revealed low albumin (16 g/L), elevated urine protein:creatinine index (PCI) (341 mg/mmol), elevated TSH (148 mU/L), normal T4 (11 pmol/L) and significant hypercholesterolaemia. Following nephrology consultation and renal biopsy showing minimal change disease, the diagnosis of nephrotic syndrome was made. Nephrotic syndrome has been rarely reported in association with Graves’ disease. Reports show membranous glomerulonephritis rather than minimal change disease. In nephrotic syndrome, there is increased permeability of the glomerular basement membrane to large molecules. Thyroxine replacement was deemed inadequate as a consequence of thyroid-binding globulin wasting. Levothyroxine dose was increased to 1150 mcg/week (1.93 µg/kg/day) initially. He had good clinical response to high-dose steroid, and this was gradually tapered over several months. At the time of publication (May 2023), his urine PCI improved to 68.47 mg/mmol. Prednisolone requirement had been reduced to 10 mg/day, along with levothyroxine dose at 850 µg/wk (1.4 µg/kg/day).

CONCLUSION
This case highlights the importance of recognising the increased levothyroxine requirement in patients with nephrotic syndrome. Although rare, the association between autoimmune thyroid disease and nephrotic syndrome should be recognised.