Endocrine Abstracts

A 44 year old woman presented with leg swelling. Past history included hypothyroidism and ulcerative colitis treated with eltroxin (100 mg/day) and azathioprine (100 mg/day) respectively. Clinical examination revealed pitting oedema to knees and a ’puffy face’. Free T4 was 5.8 pmol/l (12–22 pmol/l), TSH 84.61 mU/l (0.27–4.20), serum albumin 24 g/l (40–49 g/l). She reported good compliance with L-thyroxine and no recent gastrointestinal symptoms. L-thyroxine dose was increased to 150 µg daily. Further investigations revealed 4+ proteinuria on urine dipstick with normal creatinine. 24 hr urine collection showed 12 g proteinuria. Renal biopsy was performed. Light microscopy was normal but electron microscopy showed diffuse podocyte effacement. A diagnosis of minimal change disease likely secondary to NSAID exposure was made. She was commenced on prednisolone 60 mg/day, with remission of her nephrotic syndrome. Her thyroid function normalized and she reverted to 100 mg of eltroxin daily. Our patient presented with gross hypothyroidism and oedema which could have been mistaken for myxoedema. Her hypothyroidism had previously been stable on replacement, however, and she was compliant with her medication. Nephrotic syndrome results in urinary loss of free and protein-bound thyroid hormones and can result in increased thyroxine requirements¹. When evaluating patients with increasing thyroxine requirements, nephrotic-range proteinuria should be considered in addition to causes such as poor compliance with treatment or malabsorption of thyroxine.

Reference

1. Junglee NA, Scanlon MF, Rees DA. Increasing thyroxine requirements in primary hypothyroidism: don’t forget the urinalysis!