Endocrine Abstracts

Introduction: The most common cause of loss of adequate substitution on a stable dose of replacement therapy is noncompliance. Impaired absorption and weight gain are also possible. We present a rare case of renal loss of thyroxin in severe nephritic syndrome.

Case report: We present a 46 year old female after total thyroidectomy for Graves-Basedow disease. From 2005 she was euthyroid on a stable dose of L-thyroxin (100 μg/day). On physical examination she had oedemas of the lower extremities. A marked hypercholesterolemia (17.49 mmol/l, normal range 0–5.2 mmol/l) and a very high TSH value (92.5 mU/l, normal range 0.27 - 4.2 mU/l) were found. Celiac disease was excluded, abdominal ultrasound was performed with a normal finding. During examination proteinuria (6.19 g/day, normal range to 0.14 g/d) and thyroxin loss in urine (50 μg/l) were found. Renal biopsy was performed with the finding of membranous glomerulopathy (glomerulonephritis). Treatment will be started in nephrology department. After increase of L-thyroxin dose (300 μg/den) normalisation of TSH was established.

Conclusion: Nephrotic syndrome increases L-thyroxine requirements because of urinary loss of free and protein-bound thyroid hormones. Physical examination, careful history taking and laboratory findings are the key to the accurate diagnosis. After treatment of membranous glomerulopathy reduction of L-thyroxin dose is expected.