Electrolytes Flashcards
What causes Spurious Hyponatremia?
Blood is drawn proximal to IV infusion or central line
When can you see Pseudohyponatremia?
Instruments that use “indirect” method, sample is prediluted before analysis
How do analyzers that use the “indirect” method of calculating Soldium work?
Calculate the plasma/serum sodium on the assumption that the H20 content of plasma is 93%.
When might the assumption that the H20 content of plasma is 93% be incorrect?
- Hypertriglyceridemia
- Hypercholesterolemia
- Hyperproteinemia
*Water content in original sample is LOWER
How does Hyperglycemia affect Sodium?
- Shift in Na+ into Extracellular space
* True hyponatremia, but unrelated to any intrinsic defect in sodium homeostasis
Formula used to assess the degree of change in sodium concentration attributable to glucose
1.6 X (serum glucose - 100) / 100
What does Hypertonic (>295 mOsm/kg) Hyponatremia suggest?
- Hyperglycemia (marked)
- Mannitol (reduce ICP)
Hypotonic Hyponatremia (<280 mOsm/kg): -Hypovolemic (Renal Loss) (5)
Increased Urine Sodium
- Diuretics
- Renal medullary dz
- Addison dz (primary adrenal insuff.)
- RTA type I
- Cerebral salt wasting syndrome
Hypotonic Hyponatremia (<280 mOsm/kg): -Hypovolemic (Extrarenal loss) (2)
Low Urine Sodium
- GI (V/D)
- 3rd spacing (peritonitis/pleuritis)
Hypotonic Hyponatremia (<280 mOsm/kg): -Euvolemic (9)
- SIADH
- Psychogenic polydipsia
- HypOthroidism
- Addison Dz
- ADH/Vasopressin-like drugs
- Desmopressin
- SSRis
- TCAs
- MDMA
Hypotonic Hyponatremia (<280 mOsm/kg): -Hypervolemic (3)
- CHF
- Cirrhosis
- Nephrotic syndrome
When do you most commonly see Hypernatremia?
Excess water loss and inability to respond to thirst response (Infants, ICU, debilitated)
Hypernatremia:
-Central Diabetes Insipidus
Damage to hypothalamus or nuerohypophysis
Hypernatremia:
-Nephrogenic (5)
Diseases that affect Medullary space: -Sickle Cell, Tubulointerstitial nephritis Electrolyte disturbances: -HypOKalemia and HyperCalcemia Renal Tubular Acidosis Fanconi Syndrome Drugs: -Lithium, democlocyline, colchicine, AmptoB, gentamicin, furosemide
General causes of Hypokalemia. (3)
- Renal loss
- GI loss
- Transcellular shift
Hypokalemia:
-Renal loss (10)
Urinary K+ >30mEq/day
- Diuretics
- Hypomagensemia
- Abx
- Minearlocorticoid excess
- RTA types I and II
- CAH
- Bartter syndrome
- Liddle syndrome
- Gitelmand syndrome
- Licorice (glyceyrrhizin)
Hypokalemia:
-GI loss (4)
- Vomiting
- NG tube suction
- Diarrhea
- Villous Adenoma
Hypokalemia:
-Transcellular shift (2)
- Metabolic Alkalosis
- Correction of DKA
What happens to Potassium in DKA?
- Initial Hyperkalemia
- Profound Hypokalemia with correction of DKA
*Must give supplemental K+
What happens to Potassium in Acidotic states?
HyperKalemia
What are the acidotic states that are NOT associated with hyperkalemis?
RTA types I and II (hypokalemia)
T/F: 50% of serum calcium is bound to protein.
True; primarily Albumin
What are Calcium levels in a patient with Hypoalbuminemia?
- Total calcium LOW
- Free (ionized) calcium is Normal
What happens to Calcium in acidosis?
- Decreases binding of calcium to Albumin
- Increases the proportion of free calcium
