Sodium Balance Flashcards
What is diabetes insipidus?
either too little vasopressin is produced by the pituitary – ‘cranial diabetes insipidus’ or the kidney becomes insensitive to vasopressin and does not make aquaporin channels and reabsorb water from the collecting ducts – ‘nephrogenic diabetes insipidus’.
What are the signs of diabetes insipidus?
Polyuria, polydipsia
How is diabetes insipidus diagnosed?
Hypernatriemia after water restriction test
What are the signs of SIADH?
Urine has a high sodium content or osmolality while serum sodium levels drop (hyponatraemia) as water is retained. Serum osmolality is low whilst urine osmolality is high.
Which medications cause SIADH and hyponatriemia?
diuretics (especially thiazides), selective serotonin reuptake inhibitors (SSRIs), antipsychotics such as haloperidol, nonsteroidal anti-inflammatories and carbamazepine.
