DSA Flashcards

1
Q

What is the NORMAL range for Plasma [K+]?

A

3.5-5.0 mEq/L

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2
Q

What is the NORMAL K+ distribution in the body?

A

Total K+ = 3500 mEq

ICF = 98%

  • 80% Muscle Cells
  • 20% Other Cells

ECF = 2 % (3.5-5.0 mEq/L)

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3
Q

What accounts for the 30 FOLD difference between ECF and ICF [K+]?

A
  1. Na+/K+ ATPase
  2. NKCC2
  3. K+ Channels
  4. Transcellular distribution via other factors
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4
Q

What values define HYPOkalemia?

A

Plasma [K+] < Approx. 3.7 mEq/L

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5
Q

What are 4 COMMON causes of HYPOkalemia?

A
  1. Vomiting / Diarrhea
  2. Insulin EXCESS
  3. Deficiency
  4. Alkalosis
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6
Q

What are the values for HYPERkalemia?

A

Plasma [K+] > Approx. 5.2 mEq/L

LETHAL > 10 mEq/L

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7
Q

What are 3 COMMON causes of HYPERkalemia?

A
  1. Excessive Intake
  2. Tissue Related
    - Rhabdomyolysis
    - Burns
    - Hemolysis
  3. Shifts from ICF —> ECF
    - Acidosis
    - Insulin Deficiency
    - Hypergylcemia
    - Tissue Damage
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8
Q

What is PSEUDOhyperkalemia?

A

Artificially high plasma [K+] due to RBC lysis while blood drawn.

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9
Q

What are 2 major routes of K+ LOSS from the body?

A
  1. Kidneys —> Urine (Majority)

2. GI —> Feces

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10
Q

In regards to EXCITABLE tissue cells, how does HYPOkalemia effect resting membrane potential?

A

HYPOkalemia results in HYPERPOLARIZED resting membrane.

Membrane is MORE NEG. —> Stronger impulse needed to fire.

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11
Q

In regards to EXCITABLE tissue cells, how does HYPERkalemia effect resting membrane potential?

A

HYPERkalemia results in HYPOPOLARIZED resting membrane.

Membrane is LESS NEG. —> Less impulse needed to fire.

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12
Q

In CARDIAC cells, how do HYPOkalemia and HYPERkalemia effect membrane potential, respectively?

A

HYPOkalemia —> HYPOpolarizes membrane

HYPERkalemia —> HYPERpolarizes membrane

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13
Q

What are the characteristic EKG changes seen with HYPOkalemia and HYPERkalemia, respectively?

A

HYPOkalemia —> LOW T-Wave

HYPERkalemia —> PEAKED T-Wave

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14
Q

What is the normal value for dietary Ca2+ intake?

A

Approximately 1000 mg/day (Adults)

Note: Absorption best if at doses <500 mg in one sitting.

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15
Q

Which group is at the highest risk for Ca2+ deficiency?

A

Adolescents

Followed by:

  • Postmenopausal women
  • Vegetarians
  • Lactose Intolerant
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16
Q

Where are the 3 places Ca2+ can enter circulation?

A
  1. Resorption from kidney
  2. Resorption from bone
  3. Ingestion via GI Tract / Diet
17
Q

What are the major routes of Ca2+ LOSS from the body?

A

Feces - Majority

Urine

18
Q

Which enzyme is involved in Ca2+ ABSORPTION from the GI Tract?

A

Calcitriol

19
Q

Which enzymes are involved in bone formation? Resorption?

A

Bone Formation - Calcitonin

Bone Resorption - PTH, Calcitriol

20
Q

How does HYPOcalcemia effect neuromuscular excitability?

A

INCREASES neuromuscular excitability

21
Q

How does HYPERcalcemia effect neuromuscular excitability?

A

DECREASES neuromuscular excitability

22
Q

What are the 2 differential diagnoses (Ddx) for HYPERcalcemia?

A
  1. Primary Hyperparathyroidism

2. Malignancy

23
Q

What are the 3 differential diagnoses (Ddx) for HYPOcalcemia?

A
  1. HYPOparathyroidism
  2. Renal Disease
  3. Vitamin D Deficiency
24
Q

What is the normal dietary intake requirement for phosphate?

A

Approximately 1500 mg/day.

25
Q

What are the 3 major pools (and %) for phosphate storage?

A
  1. Bone - 85%
  2. Cells - 14%
  3. Serum - 1%
26
Q

What are the 3 major routes for phosphate loss in the body?

A
  1. Stool
  2. Urine
  3. Bone Formation
27
Q

Which factor is important in kidney phosphate resorption?

A

Tmax

28
Q

What are the 4 main regulators of phosphate metabolism?

A
  1. Dietary
  2. Calcitriol
  3. PTH
  4. Renal Tubular
29
Q

What are the major store pools (and %) of Mg2+ in the body?

A
  1. Bone - 50%
  2. ICF (especially muscle) - 49%
  3. ECF - 1%
30
Q

What are the 2 major ways for Mg2+ excretion?

A
  1. Feces (Majority)

2. Urine

31
Q

What is the normal total serum Mg2+ range? Normal free serum Mg2+ range?

A

Total Serum Mg2+ = 1.8 mEq/L and (1.8-2.2 mg/DL)

Free Serum Mg2+ = 0.8-1.0 mEq/L