Electrolytes Flashcards
How do you calculate pts serum osmoles?
2Na + (glu/ 18) + (Bun/ 2.8) = serum osmoles
What is the basic work up of hyponatremia?
- Serum osmoles
- Urine Na
- Urine osmoles
Causes of Hypertonic Hyponatremia
False elevation
Ingestion: alcohols
Glucose: for every 100 above 100 add 1.6 to your measured Na
Fix alcohol problem or glucose correction
Causes of isotonic Hyponatremia
Fats and proteins in sample
No tx of Na needed
Hyponatremic patient with Hypotonic Hyponatremia. What’s the first thing you check?
H&P
i.e volume status
Patient with hypotonic hypernatremia with hypervolemia (i.e volume overload)
What’s the treatment?
Diuresis
Patient with hypotonic hyponatremia and hypovolemia. What’s the treatment?
IVF trial
If they get better continue IV fluids if they get worse it’s probably euvolemic. And you need to water restrict and rule out RATS.
In the patient with hypotonic hypernatremia and euvolemia you must rule out RATS.
What is RATS?
Rta IV
Addison’s
Thyroid
Siadh
What is the treatment for hypotonic hyponatremia with euvolemia?
Water restriction.
In a hyponatremic patient with hypotonic Hyponatremia with a history of fever tachycardia heat exposure or water restriction what is this patients volume status?
Hypovolemic
Tx: IVF
In a patient with hyponatremia:
- Hypotonic serum
- UNa low (300)
What is this patients volume status and tx?
Volume down
Tx: IVF
In a patient with hyponatremia:
- Hypotonic serum
- UNa high
- Uosm low
What is the volume status and tx?
Volume up
Tx: Diuresis
And a patient with hyponatremia:
- Hypotonic serum
- UNa high
- Uosm high
What is the diagnosis and treatment?
Euvolemia
SIADH
Tx: vasopressin
What is hyponatremia?
Na < 135
What is severe hyponatremia?
Technically Na < 125
But for use of 3% saline usually we look at listing 110, coma, or seizures
How do you treat symptomatic (Neuro changes) severe hyponatremia? (<110, coma, or seizures)
3% saline
How do you calculate how much 3% saline to giveA patient with severe hyponatremia?
- Na+ deficit
- Volume of 3% saline needed
- Time needed for correction
- Rate of infusion
How do you calculate sodium deficit?
Na+ Deficit (mEq) = (Desired Na+ - Measured Na+) x 0.6 L/kg x Weight (kg)
How do you calculate volume of 3% saline needed to correct severe hyponatremia?
Volume of 3% Saline = (Na+ Deficit)/513 mEq/L Na+
How do you calculate time needed to correct sodium in severe hyponatremia?
Time Needed for Correction = (Desired Na+ - Measured Na+)/0.5 mEq/L per hour
How do you calculate infusion rate of 3% saline in severe hyponatremia correction?
Rate = (Volume of 3% Saline)/(Time Needed for Correction)
What is hypokalemia?
Hypokalemia is generally defined as a serum potassium level of less than 3.5 mEq/L (3.5 mmol/L). Severe hypokalemia is a level of less than 2.5 mEq/L.
How much K to give?
10 mEq to move up 0.1 for K >3
(100 mEq to get to 4 over 10 hours)
15mEq for every 0.1 between 2.5 and 3.0 (75mEq)
20mEq for every 0.1 between 2.0 and 2.5 (100mEq)
What’s the first thing you do if you have hyperkalemia?
EKG and recheck potassium
Treatment in hyperkalemia
- IV CaCl
- 10 U regular insulin, 1 amp D50, 10mg albuterol, maybe NaBicarb
- Kayexalate, DIALYSIS
EKG changes in hyperK
- Wide QRS
- Peaked t waves
- Sinusoidal waves
Severe Hyponatremia with coma or other neuro sxs line seizures. How do you treat?
Any patient with suspected hyponatremic encephalopathy should receive a 2 cc/kg bolus of 3% NaCl with a maximum of 100 cc, which could be repeated 1-2 times if symptoms persist. Then fluid restrict and call renal.
