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reset osmostat
Etiology:
- quadriplegia
- tuberculosis
- pregnancy
- psychiatric disorders
- chronic malnitrition
- old age
Pathology:
- downward setting of the osmostat
- lowered osmolality setpoint leads to stable hypo-osmolar hyponatremia
Laboratory:
- serum osmolality low after water ingestion, high after water restriction
- serum sodium: hyponatremia
- mild, asymptomatic hyponatremia stable on multiple measurements
Differential diagnosis:
- low solute diet
- hyponatremia may be more pronounced
- polydipsia, weight loss diet [2]
Related
osmolality (Osm)
General
osmostat
sign/symptom
References
- Medical Knowledge Self Assessment Program (MKSAP) 17, 18.
American College of Physicians, Philadelphia 2015, 2018.
- NEJM Knowledge+