Endocrine Abstracts (2008) 15 P354

Hypo-osmolar hyponatremia and orthostatic hypotension as the chief symptom in primary hypothyroidism

Arif Ullah, Kamal Abouglila, Logan Thirugnanasothy & Helen Cooper


University Hospital of North Durham, County Durham, UK.


Background: Postural hypotension has been commonly described in elderly. Common causes include medication, fluid loss, adrenal insufficiency and autonomic dysfunction. Hyponatremia is not a disease in itself, but a manifestation of a variety of disorders and side-effects of diuretics; alternatively, it may be the only manifestation of certain disorders. We present a case of primary hypothyroidism presenting as collapse with postural hypotension and severe hyponatremia.

Case report: A 75-year-old gentleman presented with history of collapse. He was not taking any medications. On examination blood pressure was 140/80 mmHg lying and 114/70 mmHg standing. Systemic examination was unremarkable. Laboratory tests showed severe hypotonic hyponatremia with normal urea and creatinine. Thyroid function test (TFT) showed TSH (30.15 mu/l), FT3 (3.8 pmol/l), FT4 (10.7 pmol/l), and thyroid antibodies were positive of 1257. His short synacthen test, LH, FSH and Prolactin were normal. Low serum sodium level was gradually corrected by water restriction. He was stared on levothyroxine replacement and resulted in correction of the orthostatic hypotension and hyponatremia.

Conclusion: Disorders of sodium and water metabolism are common in hospitalized patients. Hypothyroidism can sometime give rise to hyponatremia and hypotension. The potential mechanism, whereby hyponatremia develop is not entirely clear2 but possible due to SIADH. Treating hyponatremia can some time be challenging and this case illustrates the importance of checking thyroid status by measuring TFT.

References

1. Nakando M. Hyponatremia with increased plasma antidiuretic hormone in a case of hypothyroidism. J Int Med 2000 39 P1075–1077.

2. Kimura T. Potential mechanism of hypothyroidism induced hyponatremia. J Int Med 2000 30 P1002–1003.

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