Renal Clinical Medicine Part 2: Electrolytes (M. Selby)

Question 1

Hyponatremia is defined by?

Answer 1

Serum sodium less than 135 mEq/L

Question 2

Serum osmolarity is regulated by what 2 main systems?

Answer 2

1) ADH system

2) Thirst mechanism

Question 3

ADH is released in response to?

Answer 3

Osmotic and non-osmotic stimuli

Question 4

ADH released from increases in serum osmolarity is detected by what receptors in the anterior hypothalamus?

ADH released from non-osmotic stimuli such as decreases in blood pressure or blood volume is detected by?

Answer 4

1) Osmoreceptors

2) Arterial baroreceptors

Question 5

Besides baroreceptors, what are additional non-osmotic stimuli for ADH release?

Answer 5

1) Nausea
2) Hypoxia
3) Pain
4) Medications (Opiates and antidepressants)

Question 6

Hyponatremia results primarily from?

Answer 6

Increases in total body water

Question 7

Increases in total body water results from either?

Answer 7

1) Excessive intake of water

2) Decreased renal excretion of water

Question 8

Acute Hyponatremia is classified as?

Chronic?

Answer 8

1) Less than 48 hours

2) More than 48 hours or unknown duration

Question 9

If the patient has hypotonic hyponatremia, then what needs to be assessed?

How is this done?

If considering SIADH what else should be obtained?

Answer 9

1) Volume status of the patient
2) Measure random urine sodium level and urine osmolarity
3) Serum uric acid (Low levels indicated SIADH)

Question 10

What is the most common malignancy associated with ectopic ADH production?

Answer 10

Small cell lung cancer

Question 11

How is hyponatremia treated in symptomatic patients?

Answer 11

Hypertonic saline (3%)

Question 12

When treating chronic hyponatremia you must be careful of rapid correction of serum sodium as patient is at higher risk for?

Answer 12

Osmotic demyelination syndrome

Question 13

What are some complications of hyponatremia?

Answer 13

1) Seizures
2) Coma
3) Death from brain (uncal) herniation
4) Osmotic demyelination syndrome

Question 14

The clinical manifestations of Osmotic demyelination syndrome are typically delayed for how long after rapid Na+ correction?

Demyelination occurs in what neurons?

What symptom which may occur is characterized as the patient being awake but unable to move or talk?

Although it may take up to 4 weeks for abnormalities to be seen, what is the prefered imaging modality?

Answer 14

1) 2-6 days
2) Pontine and extrapontine neurons
3) Locked in syndrome
4) MRI

Question 15

What is a common underlying disease state predisposing to the occurence of osmotic myelinolysis?

Answer 15

Chronic alcoholism

Question 16

Hypernatremia is defined by?

Answer 16

Serum sodium greater than 145 mEq/L

Question 17

Hypernatremia is primarily seen in what populations?

Answer 17

1) Infants

2) Elderly

Question 18

What are the two ways that hypernatremia can occur?

Which is the most common cause?

Answer 18

1) Dehydration (More common)

2) Sodium overload

Question 19

What does hypernatremia result in with regards to the osmotic gradient?

Answer 19

Cellular shrinkage

Question 20

The clinical manifestations of hypernatremia are mainly?

Answer 20

Neurologic symptoms

Question 21

Acute hypernatremia is classified as?

Chronic?

Answer 21

1) Less than 48 hours

2) More than 48 hours or unknown duration

Question 22

Intracerebral hemorrhages, Subarachnoid hemorrhages, or Subdural hematomas due to hypernatremia are more common in what populations?

Answer 22

Pediatric and neonate

Question 23

When treating chronic hypernatremia you must be careful of rapid correction of serum sodium as patient is at higher risk for?

Answer 23

Cerebral edema

Question 24

The kidneys are the primary regulator of what ion?

Answer 24

Potassium

Question 25

What is the major extracellular cation? What is the major intracellular cation?

Answer 25

1) Potassium | 2) Sodium

Question 26

The regulation of potassium homeostasis by the kidneys is done primarily by?

Answer 26

Secretion of K+ in the distal parts of nephron

Question 27

Hyperkalemia is defined by?

Answer 27

Serum potassium greater 5.0 mEq/L

Question 28

What cardiac arrhythmias are associated with hyperkalemia complications?

Answer 28

1) Vfib 2) Bradycardia from AV block 3) Asystole

Question 29

Severe hyperkalemia can lead to respiratory failure from?

Answer 29

Diaphragm weakness

Question 30

Hyperkalemia decreases ammoniagenesis and thus decreases? This leads to?

Answer 30

1) Ammonium chloride excretion in the kidneys | 2) Metabolic acidosis

Question 31

What are the 2 main reasons for hyperkalemia?

Answer 31

1) Transcellular shift (increased K+ release from cells) | 2) Decreased Renal K+ excretion

Question 32

In the pathogenesis of hyperkalemia, Pseudohyperkalemia, Metabolic Acidosis, Insulin deficiency, hyperglycemia, hyperosmolality, Increased Tissue Catabolism, Medications, exercise and blood transfusions all lead to?

Answer 32

Transcellular shift (increased K+ release from cells)

Question 33

Pseudohyperkalemia results from? What are some causes of this?

Answer 33

1) An artificial increase in serum K+ due to K+ release from cells 2) RBC hemolysis, Clotted blood samples, Leukocytosis

Question 34

In the pathogenesis of hyperkalemia, decreased renal K+ excretions can be caused by?

Answer 34

1) Low aldosterone secretion 2) Aldosterone resistance 3) AKI or CKD

Question 35

In the diagnosis of hyperkalemia, how do you determine if it is due to renal or extrarenal etiology? What indicates renal etiology? What indicated extrarenal?

Answer 35

1) Fractional excretion of K+ 2) Less than 10% 2) Greater than 10%

Question 36

What ecg findings should lead you to give calcium gluconate in order to treat hyperkalemia?

Answer 36

Peaked T wave

Question 37

What is the regimen for treating hyperkalemia due to transcellular shift?

Answer 37

1) Insulin 2) Dextrose 3) B2-agonist

Question 38

In the treatment of hyperkalemia, sodium polystyrene sulfonate works by? Zirconium cyclosilicate? Patiromer?

Answer 38

1) Exchanges Na+ ions for potassium primarily in the colon 2) Exchanges Na+ and H+ ions for potassium throughout intestines 3) Exchanges Ca+ for potassium primarily in the colon

Question 39

Hypokalemia is defined by?

Answer 39

Serum potassium less than 3.5 mEq/L

Question 40

What are the clinical manifestations of hypokalemia?

Answer 40

1) Cardiac arrhythmia (PAC/PVCs) 2) Skeletal muscle weakness (diaphragmatic weakness) 3) Rhabdomyolysis 4) Metabolic alkalosis 5) Nephrogenic diabetes insipidus

Question 41

What ECG change in common with hypokalemia?

Answer 41

Prominent U wave

Question 42

What are the 3 main reasons for hypokalemia?

Answer 42

1) Transcellular shift (Increased K+ uptake by cells) 2) Extrarenal loss 3) Renal loss

Question 43

In the pathogenesis of hypokalemia, transcellular shift (increased K+ uptake by cells) can be caused by?

Answer 43

1) Insulin 2) B2 agonist 3) Metabolic alkalosis

Question 44

In the pathogenesis of hypokalemia, extrarenal loss can be caused by?

Answer 44

1) GI loss (Vomiting and Diarrhea) | 2) Cutaneous loss (sweating)

Question 45

In the pathogenesis of hypokalemia, renal loss can be caused by?

Answer 45

1) Diuretics 2) Increased mineralocorticoid activity 3) Hypomagnesemia

Question 46

What are some examples of increased mineralocorticoid activity?

Answer 46

1) Primary hyperaldosteronism (Conn’s syndrome) | 2) Hypercortisolism (Cushing Syndrome)

Question 47

In the diagnosis of hypokalemia, what is the best method for assessing renal K+ excretion?

Answer 47

24 hour urine potassium

Question 48

In the treatment of hypokalemia what is given to replace potassium deficit?

Answer 48

Potassium chloride