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Profound hyponatraemia following an idiosyncratic reaction to diuretics
A S Wierzbicki1, S G Ball, N K Singh
1Department of Chemical Pathology, Chelsea and Westminster Hospital, London, UK.
International Journal of Clinical Practice
|September 23, 1998
Summary
A thiazide diuretic caused severe hyponatremia in an elderly woman, mimicking SIADH. This case highlights the unreliability of urine:plasma osmolality ratios for diagnosing SIADH.
Area of Science:
- Nephrology
- Oncology
- Endocrinology
Background:
- Hyponatremia, a common electrolyte imbalance, can present with diverse symptoms.
- The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a frequent consideration in hyponatremia.
- Accurate diagnosis is crucial as treatment strategies differ significantly.
Observation:
- A 79-year-old woman with breast adenocarcinoma presented with altered consciousness and anorexia.
- Initial laboratory findings revealed severe hyponatremia (97 mmol/l).
- A urine:plasma osmolality ratio of 2.25 supported an initial diagnosis of SIADH.
Findings:
- Further investigations demonstrated normal antidiuretic hormone (ADH) levels.
- The patient was diagnosed with a sodium-losing state and dehydration.
- The hyponatremia was attributed to a recently prescribed thiazide diuretic.
Implications:
- This case underscores the potential for thiazide diuretics to induce significant hyponatremia.
- It highlights the limitations of relying solely on urine:plasma osmolality ratios for SIADH diagnosis.
- Clinical correlation and comprehensive evaluation are essential for accurate hyponatremia diagnosis.