Electrolyte Disturbances

Question 1

Low serum Na+

Answer 1

Nausea, malaise, stupor, coma

Question 2

High serum Na+

Answer 2

Irritability, stupor, coma

Question 3

Low serum K+

Answer 3

U waves on ECG, flattened T waves, arrhythmias, muscle weakness

Question 4

High serum K+

Answer 4

Wide QRS and peaked T waves on ECG, arrhythmias, muscle weakness

Question 5

Low serum Ca2+

Answer 5

Tetany, seizures, QT prolongation
Chvostek’s
Trousseau’s

Question 6

High serum Ca2+

Answer 6

Stones = renal
Bones = pain
Groans = abdominal pain
Moans/psychiatric overtones = anxiety, altered mental status
Not necessarily calciuria

Question 7

Low serum Mg2+

Answer 7

Tetany, torsades de pointes

Question 8

High serum Mg2+

Answer 8

Decreased DTRs, lethary, bradycardia, hypotension, cardiac arrest, hypocalcemia

Question 9

Low PO4 3-

Answer 9

Bone loss, osteomalacia

Question 10

High PO4 3-

Answer 10

Renal stones, metastatic calcifications, hypocalcemia

Question 11

Shifts K+ out of cell –> Hyperkalemia

Answer 11

Digitalis
Hyperosmolarity
Insulin deficiency (insulin shifts K+ into cells)
Lysis of cells
Acidosis
B-adrenergic antagonist

Question 12

Shifts K+ into cell –> Hypokalemia

Answer 12

Hypo-osmolarity
Insulin (increases N+/K+ ATPase)
Alkalosis
B-adrenergic agonist (increases N+/K+ ATPase)

Question 13

Total body weight breakdown

Answer 13

40% nonwater mass

60% total body water

Question 14

60% total body water breakdown

Answer 14

1/3 ECF = 20% total body weight

2/3 ICF = 40% total body weight

Question 15

Extracellular fluid breakdown

Answer 15

1/4 plasma volume = 5% total body weight

3/4 interstitial volume = 15% total body weight

Question 16

Calculation GFR

Answer 16

Inulin

Freely filtered and neither reabsorbed nor secreted

Question 17

Normal GFR

Answer 17

100 mL/min

Question 18

Estimation GFR

Answer 18

Creatinine clearance

Slightly overestimates because is moderately secreted

Question 19

Estimation ERPF

Answer 19

Para-aminohippuric acid (PAH)
Both filtered and actively secreted in proximal tubule, nearly all is excreted
Underestimates true renal plasma flow by 10%

Question 20

Prostaglandins _____ the _____ arteriole

Answer 20

Prostaglandins DILATE the AFFERENT arteriole

Question 21

Angiotensin II _____ the _____ arteriole

Answer 21

Angiotensin II CONSTRICTS the EFFERENT arteriole

Question 22

Respiratory acidosis

Answer 22

pH 40 mmHg

Question 23

Respiratory acidosis causes

Answer 23

*Hypoventilation*
Airway obstruction
Acute lung disease
Chronic lung disease
Opioids, sedatives
Weakening of respiratory muscles

Question 24

Metabolic acidosis with compensation (hyperventilation)

Answer 24

pH

Question 25

Anion gap

Answer 25

Na+ - (Cl- + HCO3-)

Normal = 8-12 mEq/L

Question 26

Causes of metabolic acidosis with increased anion gap

Answer 26

MUDPILES:
Methanol (formic acid)
Uremia
Diabetic ketoacidosis
Propylene glycol
Iron tablets or INH (isoniazid)
Lactic acidosis
Ethylene glycol (oxalic acid)
Salicylates (late)

Question 27

Causes of metabolic acidosis with normal anion gap

Answer 27

HARD-ASS:
Hyperalimentation
Addison disease
Renal tubular acidosis
Diarrhea
Acetazolamide
Spironolactone
Saline infusion

Question 28

Respiratory alkalosis

Answer 28

pH > 7.4

Pco2

Question 29

Respiratory alkalosis causes

Answer 29

*Hyperventilation*
Hysteria
Hypoxemia = high altitude)
Salicylates (early)
Tumor
Pulmonary embolism

Question 30

Metabolic alkalosis with compensation (hypoventilation)

Answer 30

pH > 7.4

Pco2 > 40 mmHg

Question 31

Metabolic alkalosis causes

Answer 31

Loop diuretics
Vomiting
Antacid use
Hyperaldosteronism

Question 32

Henderson Hasselbalch Equation

Answer 32

pH = 6.1 + log([HCO3-]/0.03xPco2)

Question 33

Winters Formula

Answer 33

Predicted respiratory compensation for simple metabolic acidosis
Pco2 = 1.5[HCO3-] + 8 +/- 2