click below
click below
Normal Size Small Size show me how
Renal - Hyponatremia
ACP Nephrology p11
| Question | Answer |
|---|---|
| Formula for total osmolality | 2 x Serum sodium + plasma glucose / 18 + BUN / 2.8 |
| Does urea exert an osmotic effect? | No because it is freely diffusible across most cell membranes |
| What is normal osmolality | 280-285 (or 275 - 295) |
| What is the function of ADH? | Promotes water reabsorption in the distal tubule and collecting duct of the kidney (causes fluid retention). Also has a peripheral vasoconstriction effect. |
| Serum sodium under which a patient is considered to have hyponatremia | 135 |
| First step in assessing hyponatremia | Serum sodium less than or equal to 135 |
| Second step in assessing hyponatremia | Is the patient symptomatic? |
| What are mild symptoms of hyponatremia? | Headache, lethargy, dizziness |
| What are symptoms of severe hyponatremia? | confusion, ataxia, seizures, obtundation, coma, respiratory depression |
| If a patient with hyponatremia is asymptomatic or has mild symptoms, then what is the next step? | Assess serum osmolality. Hypotonic hyponatremia is osmolality < 280. Isotonic hyponatremia is osmolality 280-285. Hypertonic hyponatremia's osmolality > 285. |
| What is the differential for isotonic hyponatremia? | Hyperproteinemia or hyperlipidemia |
| What is the differential for hypertonic hyponatremia? | Hyperglycemia, mannitol, sorbitol, contrast |