Renal - Calcium, Sodium, and Potassium

Question 1

What does calcium bind on the parathyroid glands to inhibit PTH synthesis?

Answer 1

Calcium sensing receptors (CaSR)

Question 2

Chronic kidney disease may cause _________ of the parathyroid glands.

Answer 2

Chronic kidney disease may cause hyperplasia of the parathyroid glands.

Question 3

Why may chronic kidney disease result in hyperparathyroidism?

Answer 3

Decreased serum calcium

+

increased serum phosphate

Question 4

Serum osmolality is mainly decided by what three serum substances?

Answer 4

Sodium;

BUN;

glucose

Question 5

Serum osmolality = _____ (Na) + (BUN) / _____ + (glucose) / _____,

Answer 5

Serum osmolality = 2 (Na) + (BUN) / 2.8 + (glucose) / 18,

Question 6

True/False.

Total body water dictates total body sodium.

Answer 6

False.

Total body sodium dictates total body water.

Question 7

What is the major determinant of extracellular fluid volume?

Answer 7

Serum sodium

Question 8

Changes in what ECF ion will affect the resting potential of contractile cells?

Answer 8

K⁺

Question 9

Changes in what ECF ion will affect the threshold potential of contractile cells?

Answer 9

Ca²⁺

Question 10

______kalemia causes muscle weakness.

Answer 10

Hypokalemia causes muscle weakness.

Question 11

______kalemia causes arrhythmias due to more frequent cardiac action potentials.

Answer 11

Hyperkalemia causes arrhythmias due to more frequent cardiac action potentials.

Question 12

Epinephrine moves potassium _______ (into/out of) the cells.

Answer 12

Epinephrine moves potassium into the cells.

Question 13

Beta blockers moves potassium _______ (into/out of) the cells.

Answer 13

Beta blockers moves potassium out of the cells.

Question 14

The majority of K⁺ is reabsorbed in what part of the nephron?

Answer 14

The PCT

Question 15

When K⁺ is depleted, more is reabsorbed in the ___________.

Answer 15

When K⁺ is depleted, more is reabsorbed in the collecting duct.

Question 16

K⁺ excretion is dependent on (and fine-tuned by) ____________ K⁺ secretion.

Answer 16

K⁺ excretion is dependent on (and fine-tuned by) collecting duct K⁺ secretion.

Question 17

Sustained disorders of potassium are usually _________ in origin.

Answer 17

Sustained disorders of potassium are usually renal in origin.

Question 18

True/False.

Hyperkalemia is often associated with hyperaldosteronism.

Answer 18

False.

Hypokalemia is often associated with hyperaldosteronism.

Question 19

Sustained hyperkalemia is often associated with what?

Answer 19

Renal failure

Question 20

Increased distal sodium delivery and aldosterone __________ K+ secretion/wasting.

Answer 20

Increased distal sodium delivery and aldosterone increase K+ secretion/wasting

Question 21

True/False.

Certain antibiotics can prevent potassium excretion and cause hyperkalemia.

Answer 21

True.

Question 22

If a patient has hyperkalemia and EKG changes, the most important first step is to stabilize the ______________ via administration of ______________.

Answer 22

If a patient has hyperkalemia and EKG changes, the most important first step is to stabilize the cardiac membrane via administration of calcium gluconate.

Question 23

A very ill patient with elevated potassium levels is found to have moderate blood on urinary dipstick with only one RBC / field on light microscopy.

What explains this presentation?

Answer 23

Rhabdomyolysis

(the moderate blood identified is actually hemoglobin!)

Question 24

Answer 24

C.

(leading to overactive ENaC, aka Liddle syndrome)

Question 25

Urine at an osmolarity of _________ mOsm/Kg H₂O is considered ~100% dilute.

Answer 25

Urine at an osmolarity of **_\< 100_** mOsm/Kg H₂O is considered ~100% dilute.

Question 26

Urine at an osmolarity of _________ mOsm/Kg H2O is considered ~100% concentrated.

Answer 26

Urine at an osmolarity of **_\> 1200_** mOsm/Kg H2O is considered ~100% concentrated.

Question 27

Reabsorption is still isotonic in which part of the nephron?

Answer 27

The PCT

Question 28

Someone with hyponatremia would typically have a ____ serum osmolality (\_\_\_\_tonic).

Answer 28

Someone with hyponatremia would typically have a **_low_** serum osmolality (**_hypo_**tonic).

Question 29

What is here described: *A high serum osmolality (hypertonic) due to hyperglycemia. Think of this hyponatremia as* **hyperosmotic** *hyponatremia secondary to hyperglycemia.*

Answer 29

**Translocational hyponatremia** (not a 'true' hyponatremia -- a relative hyponatremia)

Question 30

What is here described: *A normal serum osmolality (isotonic) with associated hyponatremia due to elevated lipids or proteins (note: can be viral particles). Think of this hyponatremia as a* *hyponatremia secondary to hyperglycemia.*

Answer 30

**Isotonic hyponatremia** | (pseudohyponatremia)

Question 31

Translocational hyponatremia is due to elevated serum \_\_\_\_\_\_\_\_\_\_.

Answer 31

Translocational hyponatremia is due to elevated serum **_glucose_** (a hyperosmotic, relative hyponatremia).

Question 32

Pseudohyponatremia (isotonic hyponatremia) is due to elevated serum \_\_\_\_\_\_\_\_\_\_.

Answer 32

Pseudohyponatremia (isotonic hyponatremia) is due to elevated serum **_lipids or proteins_** (a relative hyponatremia).

Question 33

Hyponatremia with hypoosmolar serum is typically due to an elevation of which hormone?

Answer 33

ADH

Question 34

A patient presents with a hypervolemic hyponatremia. Urine osmolality is \< 100 mOsm/Kg, indicating _low ADH_. Name two behaviors and/or conditions that could cause this presentation.

Answer 34

(1) **Poor sodium/protein intake** (e.g. tea and toast diet; beer potomania; etc.) (2) **Psychogenic polydipsia** * (Either way, the solvent : solute ratio is greatly elevated.)*

Question 35

If someone has true hyponatremia with a urine osmolality of _______ mOsm / Kg, think tea and toast diet, beer potomania, or primary psychogenic polydipsia. These are all disorders with too little solute and/or too much solute + __________ (preserved / decreased) ADH secretion.

Answer 35

If someone has true hyponatremia with a urine osmolality of **_\< 100_** mOsm / Kg, think tea and toast diet, beer potomania, or primary psychogenic polydipsia. These are all disorders with too little solute and/or too much solute + **_decreased_** ADH secretion.

Question 36

If someone has true hyponatremia with a urine osmolality ______ mOsm / Kg, recognize ADH is present, and we need to determine volume status.

Answer 36

If someone has true hyponatremia with a urine osmolality **_\> 100_** mOsm / Kg, recognize ADH is present, and we need to determine volume status.

Question 37

How does SIADH present in terms of volume status and serum sodium levels?

Answer 37

Euvolemic hyponatremia

Question 38

Euvolemic hyponatremia is a sign of what disorder?

Answer 38

SIADH

Question 39

Hypernatremia is almost always due to a lack of what?

Answer 39

Water

Question 40

Diabetes Insipidus will have what serum sodium presentation?

Answer 40

Normal or high

Question 41

Psychogenic polydipsia will have what serum sodium presentation?

Answer 41

Low

Question 42

A patient presents with altered mental status, a BP of 130/80 mmHg, a RR of 20, a serum sodium of 125 mEq/L, a urine osmolality of 600 mOsm/kg. What is the most likely cause of this person’s hyponatremia? A. SIADH B. Decreased ECF volume C. Heart failure

Answer 42

A. SIADH (often associated with small cell carcinomas --- check for 40-year smoking history)

Question 43

What substance is released by the body with the _primary_ goal of decreasing serum phosphorus?

Answer 43

FGF23

Question 44

What is the _primary_ goal of FGF23?

Answer 44

To decrease serum phosphorus

Question 45

What is tertiary hyperparathyroidism?

Answer 45

Excessive PTH secretion that is **no longer** regulated ## Footnote *(often due to chronic secondary hyperparathyroidism which results in hyperplastic, nodular parathyroid glands)*

Question 46

Name a calcinomimetic that can be administered to decrease PTH secretion.

Answer 46

Cinacalcet

Question 47

**True/False**. Oral paracalcitol (calcitriol) can be used to increase serum PTH levels.

Answer 47

**False**. Oral paracalcitol (calcitriol) can be used to ***decrease*** serum PTH levels.

Question 48

Which will not tend to raise serum calcium or phosphates levels, cinacalcet or paracalcitol?

Answer 48

**Cinacalcet** (a calcimimetic; vs. paracalcitol, a synthetic calcitriol)

Question 49

What type of medication can be used to decrease serum phosphate in an isolated manner?

Answer 49

Phosphate-binders

Question 50

Elevated serum calcium and phosphorus are associated with what main cardiovascular issue?

Answer 50

Vascular calcification

Question 51

**Hyper**kalemia makes resting membrane potentials _______ (more/less) negative. **Hypo**kalemia makes resting membrane potentials _______ (more/less) negative.

Answer 51

**Hyper**kalemia makes resting membrane potentials **_less_** negative. **Hypo**kalemia makes resting membrane potentials **_more_** negative.

Question 52

How does NaCl reabsorption increase K⁺ excretion?

Answer 52

By creation of a **negative lumen** (Na⁺ reabsorption happens much faster than Cl^-)

Question 53

What are the most common causes of hypokalemia?

Answer 53

Renal or GI loss

Question 54

Describe urine K⁺ levels in each of the following scenarios: Hyperglycemia - \_\_\_\_\_\_\_\_\_ Diarrhea - \_\_\_\_\_\_\_\_\_

Answer 54

Describe urine K⁺ levels in each of the following scenarios: Hyperglycemia - **_Increased_** Diarrhea - **_Decreased_**

Question 55

Describe urine K+ levels in each of the following scenarios: Vomiting - \_\_\_\_\_\_\_\_\_

Answer 55

Describe urine K+ levels in each of the following scenarios: Vomiting - **_Increased_** (secondary hyperaldosteronism)

Question 56

Describe urine K+ levels in each of the following scenarios: Laxatives - \_\_\_\_\_\_\_\_\_ Diuretics - \_\_\_\_\_\_\_\_\_

Answer 56

Describe urine K+ levels in each of the following scenarios: Laxatives - **_Decreased_** Diuretics - **_Increased_**

Question 57

Acidosis is associated with \_\_\_\_\_\_\_kalemia. Alkalosis is associated with \_\_\_\_\_\_\_kalemia.

Answer 57

Acidosis is associated with **_hyper_**kalemia. Alkalosis is associated with **_hypo_**kalemia.

Question 58

Proximal RTA (type II) and distal RTA (type I) are associated with hypokalemia in the presence of ___________ blood pressure.

Answer 58

Proximal RTA (type II) and distal RTA (type I) are associated with hypokalemia in the presence of **_normal or low_** blood pressure.

Question 59

Proximal RTA refers to a type ____ RTA.

Answer 59

Proximal RTA refers to a type **_II_** RTA.

Question 60

Distal RTA refers to a type ____ RTA.

Answer 60

Distal RTA refers to a type **_I_** RTA.

Question 61

What effect do Gitelman's or Bartter's syndrome have on blood pressure?

Answer 61

Normal or decreased

Question 62

Gitelman's syndrome mimics the effects of what medication class?

Answer 62

Thiazide diuretics

Question 63

Bartter's syndrome mimics the effects of what medication class?

Answer 63

Loop diuretics

Question 64

Hypokalemia in the presence of hypertension typically indicates what type of disorder?

Answer 64

**Hyperaldosteronism** (either primary/low-renin or secondary/high-renin)

Question 65

Liddle's syndrome is associated with hypokalemia in the presence of _________ blood pressure.

Answer 65

Liddle's syndrome is associated with hypokalemia in the presence of **_elevated_** blood pressure.

Question 66

Tumor lysis syndrome is associated with an abrupt increase in which serum contents?

Answer 66

**Potassium**; uric acid; phosphate (decreased calcium)

Question 67

Aldosterone deficiency is associated with a type ____ RTA.

Answer 67

Aldosterone deficiency is associated with a type **_IV_** RTA.

Question 68

What drug can be used as a potassium-binder in patients with hyperkalemia?

Answer 68

Kayexalate

Question 69

Sustained hyperkalemia is always due to a ________ cause.

Answer 69

Sustained hyperkalemia is always due to a **_renal_** cause.

Question 70

What is the mainstay of treatment for hypernatremia?

Answer 70

Hydration