Abnormal Taste Perception Can Signal SIADH Resulting from Lung Cancer

NEW YORK MAR 27, 2006 (Reuters Health) - Patient reports of abnormal taste perception - also known as dysgeusia - should trigger consideration of a diagnosis of syndrome of inappropriate antidiuretic hormone (SIADH) resulting from lung cancer, especially when all tastes are interpreted as sweet, Japanese researchers report.

While abnormal taste sensations often occur in cancer, the scenario in which all tastes are interpreted as sweet is rare. Fewer than ten cases have been reported in the literature, according to the researchers from Saitama Medical School, Japan, who publish the case of a woman who described nearly all food as having an unpleasant sweet taste in the March issue of the Journal of Neurology, Neurosurgery and Psychiatry.

After biochemical and radiological investigations, the sole anomaly detected was hyponatremia (113 mmol/l). After 5 days of water restriction, serum sodium concentrations normalized (124 mmol/l) and dysgeusia disappeared.

However, after one week spent out of the hospital, dysgeusia symptoms returned, and the serum sodium dropped to 109 mmol/l. Urinary osmolality increased to 489 mOsm/kg, while serum osmolality dropped to 226 mOsm/kg, leading to a diagnosis of SIADH.

A CT of the chest revealed a lesion in the right superior lobe as well as periaortic and peribronchial nodules. A lymph node biopsy lead to the diagnosis of neuroendocrine large cell carcinoma, the authors write.

Trying to explain this rare case, the authors hypothesize that hyponatremia might increase the sensitivity of lingual sweetness receptors and that the tumor itself might also secrete an unknown taste modifying agent, causing patients with dysgeusia to interpret all food as sweet.

SOURCE:

• J Neurol Neurosurg Psychiatry 2006;77:405-406.