Renal - Physiology (Electrolytes, Acid-Base, & Renal tubular acidosis)

Question 1

Name 2 substances that cause K+ to shift out of cells (causing hyperkalemia).

Answer 1

(1) Digitalis (2) Beta-adrengergic antagonist; Think: D & B in “Patient with hyperkalemia? DO Insulin LAB”

Question 2

Name 4 conditions/processes that cause K+ to shift out of cells (causing hyperkalemia).

Answer 2

(1) HyperOsmolarity (2) Insulin deficiency (3) Lysis of cells (4) Acidosis; Think: O, Insulin, & LA in “Patient with hyperkalemia? DO Insulin LAB”

Question 3

Name 6 factors (i.e., substances and conditions/processes) that cause K+ to shift out of cells (causing hyperkalemia).

Answer 3

(1) Digitalis (2) HyperOsmolarity (3) Insulin deficiency (4) Lysis of cells (5) Acidosis (6) Beta-adrenergic antagonists

Question 4

Name 4 factors that cause K+ to shift into cells (causing hypokalemia).

Answer 4

(1) Hypoosmolarity (2) Insulin (increase Na+/K+ ATPase) (3) Alkalosis (4) Beta-adrenergic agonist (increase Na+/K+ ATPase)

Question 5

What influence does insulin have on K+ equilibrium, and via what mechanism?

Answer 5

Increases Na+/K+ ATPase; Think: “INsulin shifts K+ INto cells”

Question 6

What signs/symptoms are associated with a low versus high Na+ serum concentration?

Answer 6

LOW Na+ SERUM CONCENTRATION - Nausea and malaise, stupor, coma; HIGH Na+ SERUM CONCENTRATION - Irritability, stupor, coma

Question 7

What signs/symptoms are associated with a low versus high K+ serum concentration?

Answer 7

LOW K+ SERUM CONCENTRATION - U waves on ECG, flattened T waves, arrythmias, muscle weakness; HIGH K+ SERUM CONCENTRATION - Wide QRS and peaked T waves on ECG, arrythmias, muscle weakness

Question 8

What signs/symptoms are associated with a low versus high Ca2+ serum concentration?

Answer 8

LOW Ca2+ SERUM CONCENTRATION - Tetany, seizures, QT prolongation; HIGH Ca2+ SERUM CONCENTRATION - Stones (renal), bones (pain), groans (abdominal pain), psychiatric overtones (anxiety, altered mental status), but not necessarily calciuria

Question 9

What signs/symptoms are associated with a low versus high Mg2+ serum concentration?

Answer 9

LOW Mg2+ SERUM CONCENTRATION - Tetany, Torsades de pointes; HIGH Mg2+ SERUM CONCENTRATION - decreased DTRs, lethargy, bradycardia, hypotension, cardiac arrest, hypocalcemia

Question 10

What signs/symptoms are associated with a low versus high (PO4)3- serum concentration?

Answer 10

LOW (PO4)3- SERUM CONCENTRATION - bone loss, osteomalacia; HIGH (PO4)3- SERUM CONCENTRATION - Renal stones, metastatic calcifications, hypocalcemia

Question 11

Give the pH, pCO2, and [HCO3-] changes associated with Metabolic acidosis. Which change is compensatory?

Answer 11

decreased pH, decreased pCO2 (compensatory), and decreased [HCO3-]

Question 12

What is the compensatory response for metabolic acidosis? Is it immediate or delayed?

Answer 12

Hyperventilation; immediate

Question 13

Give the pH, pCO2, and [HCO3-] changes associated with Metabolic alkalosis. Which change is compensatory?

Answer 13

increased pH, increased pCO2 (compensatory), increased [HCO3-]

Question 14

What is the compensatory response for metabolic alkalosis? Is it immediate or delayed?

Answer 14

Hypoventilation; immediate

Question 15

Give the pH, pCO2, and [HCO3-] changes associated with Respiratory acidosis. Which change is compensatory?

Answer 15

decreased pH, increased pCO2, increased [HCO3-] (compensatory)

Question 16

What is the compensatory response for Respiratory acidosis? Is it immediate or delayed?

Answer 16

Increase renal [HCO3-] reabsorption; delayed

Question 17

Give the pH, pCO2, and [HCO3-] changes associated with Respiratory alkalosis. Which change is compensatory?

Answer 17

increased pH, decreased pCO2, decrease [HCO3-] (compensatory)

Question 18

What is the compensatory response for Respiratory alkalosis? Is it immediate or delayed?

Answer 18

Decrease renal [HCO3-] reabsorption; delayed

Question 19

What is the Henderson-Hasselbach equation to use in acid-base physiology/disturbances?

Answer 19

pH = 6.1 + log ([HCO3-]/[0.03*pCO2])

Question 20

In what context is the Winter’s formula used? What is the formula?

Answer 20

The predicted respiratory compensation for a simple metabolic acidosis can be calculated using Winter’s formula; pCO2 = 1.5 (HCO3-) + 8 +/- 2

Question 21

What does it mean if pCO2 measured differs significantly from what’s predicted by Winter’s formula?

Answer 21

If the measured pCO2 differs significantly from the predicted pCO2, then a mixed acid-based disorder is likely present

Question 22

Aside from normal, what are the 2 possible findings from checking arterial pH? Give values and name.

Answer 22

(1) pH < 7.4 (Acidemia) (2) pH > 7.4 (Alkalemia)

Question 23

What simple acid-base disturbance is most likely present if a patient has a pH < 7.4 and pCO2 > 40 mmHg?

Answer 23

Respiratory acidosis

Question 24

What type of breathing is associated respiratory acidosis? What are 5 other conditions associated with respiratory acidosis?

Answer 24

Hypoventilation; Airway obstruction, Acute lung disease, Chronic lung disease, Opioids/sedatives, Weakness of respiratory muscles

Question 25

What simple acid-base disturbance is most likely present if a patient has a pH < 7.4 and pCO2 < 40 mmHg?

Answer 25

Metabolic acidosis with compensation (hyperventilation)

Question 26

What further evaluation should be done if a patient is suspected to have a metabolic acidosis with compensation (hyperventilation)?

Answer 26

Check anion gap: Anion gap = Na+ - (Cl- + HCO3-)

Question 27

What are 8 conditions associated with metabolic acidosis with compensation (hyperventilation) and an increased anion gap?

Answer 27

(1) Methanol (formic acid) (2) Uremia (3) Diabetic ketoacidosis (4) Propylene glycol (5) Iron tablets or INH (6) Lactic acidosis (7) Ethylene glycol (oxalic acid) (8) Salicylates (late); Think: “MUDPILES”

Question 28

What are 7 conditions associated with metabolic acidosis with compensation (hyperventilation) and a normal anion gap?

Answer 28

(1) Hyperalimentation (2) Addison’s disease (3) Renal tubular acidosis (4) Diarrhea (5) Acetazolamide (6) Spironolactone (7) Saline infusion; Think: “HARD-ASS”

Question 29

What simple acid-base disturbance is most likely present if a patient has a pH > 7.4 and pCO2 < 40 mmHg?

Answer 29

Respiratory alkalosis

Question 30

What is the main condition associated with Respiratory alkalosis? What are 5 things that cause this?

Answer 30

Hyperventilation: (1) Hysteria (2) Hypoxemia (e.g., high altitude) (3) Salicylates (early) (4) Tumor (5) Pulmonary embolism

Question 31

What simple acid-base disturbance is most likely present if a patient has a pH > 7.4 and pCO2 > 40 mmHg?

Answer 31

Metabolic alkalosis with compensation (hypoventilation)

Question 32

What are 4 conditions/substances are associated with Metabolic alkalosis?

Answer 32

(1) Loop diuretics (2) Vomiting (3) Antacid use (4) Hyperaldosteronism

Question 33

What are the types of Rental tubular acidosis (RTA)? What is a “nickname” for each type?

Answer 33

Type 1 (“distal”), Type 2 (“proximal”), Type 4 (“hyperkalemic”)

Question 34

What is another name for type 1 RTA? What causes it?

Answer 34

(“distal”) RTA; Defect in ability of alpha intercalated cells to secrete H+

Question 35

Approximately what urine pH do untreated patients with type 1 RTA have? With what kind of electrolyte condition is type 1 RTA associated?

Answer 35

Untreated patients have urine pH > 5.5; Associated with hypokalemia.

Question 36

For what do type 1 RTA patients have an increased risk, and why?

Answer 36

Increased risk for calcium phosphate kidney stones (due to increased urine pH and bone turnover)

Question 37

What is another name for type 2 RTA? What causes it?

Answer 37

(“proximal”) RTA; Defect in proximal tubule HCO3- reabsorption.

Question 38

With what syndrome may Type 2 RTA be seen?

Answer 38

May be seen with Fanconi’s syndrome

Question 39

Approximately what urine pH do untreated patients with type 2 RTA have? With what kind of electrolyte condition is type 2 RTA associated? How do these two facts compare/contrast to Type 1 RTA?

Answer 39

Untreated patients typically have urine pH 5.5); Associated like hypokalemia (like type 1 RTA)

Question 40

For what condition do patients with type 2 RTA have an increased risk?

Answer 40

Increased risk for hypophosphatemic rickets.

Question 41

What is another name for type 3 RTA? What causes it?

Answer 41

(“hyperkalemic”) RTA; Hypoaldosteronism or lack of collecting tubule response to aldosterone.

Question 42

What is the underlying mechanism causing damage type 4 RTA? What are 2 major consequences of this?

Answer 42

The resulting hyperkalemia (from hypoaldosteronism, aldosterone resistance, or K+-sparing diuretics) impairs ammoniagenesis in the proximal tubule, leading to (1) decreased buffering capacity and (2) decreased urine pH

Question 43

What are 3 potential causes of Type 1 RTA?

Answer 43

Causes - (1) Amphotericin B toxicity (2) Analgesic nephropathy (3) Congenital anomalies (obstruction) of the urinary tract.

Question 44

What are 4 potential causes of Type 2 RTA?

Answer 44

Causes - (1) Fanconi syndrome (e.g., Wilson disease) (2) Chemicals toxic to proximal tubule (e.g., lead, aminoglycosides) (3) Multiple myeloma (light chains) and (4) Carbonic anhydrase inhibitors

Question 45

What urine pH range is associated with type 1, type 2, and type 4 RTA?

Answer 45

Type 1 (distal, pH > 5.5); Type 2 (proximal, pH < 5.5); Type 4 (hyperkalemic, pH < 5.5)

Question 46

What is RTA? In general, how is it defined?

Answer 46

Renal tubular acidosis; A disorder of the renal tubules which leads to non-anion gap hyperchloremic metabolic acidosis