Acid Base

Question 1

SAMPLE COLLECTION: Plasma vs Serum

Answer 1

Plasma: lithium heparin preferred (no EDTA, citrate, oxalate, fluoride AC bc they raise Na/K)

Serum: K levels higher in serum (0.1-0.6), in severe thrombocythemia: use plasma K

Question 2

In vitro ____, sometimes caused by a difficult blood draw, causes an ____ in the plasma/serum ____ concentration

Answer 2

hemolysis, increase, potassium

Question 3

ADH, Vasopressin

Answer 3

-Produced in hypothalamus, stored in pituitary
-Causes water to be reabsorbed by collecting ducts
-Release regulated by osmolality and baroreceptors

Question 4

Diabetes insipidus

Answer 4

kidneys do not respond to ADH (or no ADH produced)

Question 5

Aldosterone, Addison’s/Conn’s

Answer 5

-Regulates Na, HCO3, K, Cl, H
-Released by Ang II

*Addison’s: destruction of adrenal cortex, deficit of aldosterone and cortisol
*Conn’s: hyperaldosteronism

Question 6

Decrease in Anion Gap

Answer 6

Hypoproteinemia, multiple myeloma, increase in Ca/Mg, hemodilution

Question 7

Serum Osmolality

Answer 7

Question 8

Osmolality is usually measured on ___ since anticoagulants such as EDTA, oxalate, fluoride, etc. contribute to osmolality (some as much as 155 mOsm/kg!)

Answer 8

SERUM, not plasma
-Heparinized plasma, however, can be used

Question 9

A high osmolal gap suggests:

Answer 9

either the presence of another compound (e.g., ethanol) whose identity should be sought, or elevation of endogenous constituents that may not have been measured

Question 10

PH

Answer 10

Question 11

Resp/Met/Acid/Alk

Answer 11

PH
-Acidosis if < 7.35
-Alkalosis if > 7.46

In acidosis:
-Respiratory if CO2 > RR
-Metabolic if HCO3 < RR

In alkalosis:
-Respiratory if CO2 < RR
-Metabolic if HCO3 > RR

Question 12

Respiratory acidosis

Answer 12

-PCO2 high, pH low
-After compensation HCO-3 high, tCO2 high
-Urine pH low

Question 13

Metabolic Alkalosis

Answer 13

-HCO-3 high, tCO2 high; pH high
-After compensation: pCO2 high; pH high

Question 14

Respiratory alkalosis

Answer 14

-PCO2 low, pH high
-After compensation: HCO-3 low, tCO2 low, pH high

Question 15

Ionized calcium is regulated by ___ (3)

Answer 15

1,25-dihydroxyvitamin D, parathyroid hormone (PTH) and calcitonin

Question 16

Adjusted total calcium (mg/dL) =

Answer 16

Total Ca (mg/dL) + 0.8*(4-Albumin (g/dL))

= total Ca + 0.8 (4-alb)

Question 17

Hypokalemia commonly present with low ___

Answer 17

magnesium

Question 18

PARATHYROID HORMONE

Answer 18

Release regulated by ionized Ca++

Question 19

Vit D status best monitored with ___

Answer 19

25-hydroxyvitamin D (> 30 ng/mL is sufficient)

Question 20

Lower A1c values =

Answer 20

hemolytic anemia

Question 21

Higher A1c values =

Answer 21

-post-splenectomy
-polycythemia
-iron-deficiency anemia

Question 22

Definitions

Answer 22

Metabolic alkalosis - primary excess of bicarbonate
Metabolic acidosis - primary deficit of bicarbonate

Respiratory acidosis - primary excess of dCO2
Respiratory alkalosis - primary deficit of dCO2

Question 23

SIADH

Answer 23

excessive production of antidiuretic hormone, resulting in serum hypo-osmolality and urine hyperosmolality

Question 24

Respiratory Acidosis: Compensation Mechs

Answer 24

-Hemoglobin and protein buffer systems
-Hyperventilation
-Increase Na+/ H+ exchange
-Increase H2PO4, HCO-3, NH3

Question 25

Metabolic Alkalosis: Compensation Mechs

Answer 25

-HCO-3 /H2CO3 buffer system
-Hypoventilation
-Decrease Na+/H+ exchange
-Decrease NH3, HCO-3

Question 26

Respiratory Alkalosis: Compensation Mechs

Answer 26

-Decrease HCO-3, NH3, Na+/H+ exchange