Electrolytes

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1

active transport

a mechanism that requires energy to move ions across cellular membranes

2

anion

electrolytes with a negative charge that move towards the anode

3

anion gap

the difference between unmeasured anions and unmeasured cations; calculated by concentration difference

4

cation

electrolytes with a positive charge that move towards the cathode

5

diabetes insipidus

there is either no AVP production or no ability to respond to AVP in circulation; excretion increases to 10 L of urine per day; excessive thirst to prevent dehydration

6

diffusion

the passive movement of ions (no energy consumed) across a membrane and depends on both the size and charge of the ion being transported, and on the nature of the membrane through which it is passing; rate may be altered by physiologic and hormonal processes

7

electrolyte

ions (mineral) capable of carrying an electric charge; classified as either anions or cations based on charge

8

extracellular fluid (ECF)

fluid outside the cells that accounts for one-third of total body water subdivided into intravascular (plasma) and interstitial (surrounds the cells)

9

hypercalcemia

excess calcium concentrations caused by primary hyperparathyroidism (excess secretion of PTH)

10

hyperchloremia

increased Cl- concentration; result follows Na+ disturbances; may also occur when there is an excess loss of HCO3- as a result of GI losses, RTA, or metabolic acidosis

11

hyperkalemia

increased potassium concentration leading to lack of muscle excitability as a result of a higher RMP than action potential leading to paralysis or a fatal cardiac arrhythmia

12

hypermagnesemia

excessive magnesium concentrations; most commonly caused by renal failure; also caused by decreased excretion in hypothyroidism, hypoaldosteronism, and hypopituitarism, increased intake from antacids, enemas, cathartics, and therapeutic eclampsia or cardiac arrhythmia, or dehydration or bone carcinoma or metastases

13

hypernatremia

increased serum Na+ concentration; results from excess loss of water relative to Na+ loss, decreased water intake, or increased Na+ intake or retention

14

hyperphosphatemia

increased Ph concentration; high risk for those with acute or chronic renal failure; increased intake or increased release of cellular phosphate; neonates at high risk due to immature PTH and vitamin D metabolism

15

hypocalcemia

decreased calcium concentration frequently caused by hypomagnesemia by inhibiting PTH glandular secretion across parathyroid membrane, impairing PTH action at its receptor site on bone, and causing vitamin D resistance or hypermagnesaemia by inhibiting PTH release and target tissue response

16

hypochloremia

decreased Cl- concentrations usually following Na+ disturbances; may also occur with excessive loss of Cl- from prolonged vomiting, diabetic ketoacidosis, aldosterone deficiency, or salt-losing renal diseases such as pyelonephritis, or with high serum HCO3- concentrations (respiratory acidosis or metabolic alkalosis)

17

hypokalemia

decreased potassium concentration leading to decreased cell excitability by increasing RMP often resulting in an arrhythmia or paralysis; heart ceases to contract in extreme cases; causes sodium and hydrogen to move into the cell decreasing extracellular H+ resulting in alkalosis; can occur with GI or urinary loss of K+ with increased cellular uptake

18

hypomagnesemia

decreased magnesium concentration; most frequently observed in hospitalized individuals in ICUs or those receiving diuretic therapy or digitalis therapy (CHF atrial fibrillation)

19

hyponatremia

decreased sodium due to Na+ loss or water retention; most occurs with decreased osmolality

20

hypophosphatemia

decreased Ph concentration increased risk in DKA, chronic obstructive pulmonary disease, asthma, malignancy, long-term parenteral nutrition treatment, inflammatory bowel disease, anorexia, and alcoholism, increased renal excretion (hyperparathyroidism) and decreased intestinal absorption (vitamin D deficiency)

21

hypovolemia

a decreased volume of circulating blood in the body

22

intracellular fluid (ICF)

the fluid inside the cells that accounts for about two-thirds of total body water

23

osmolal gap

the difference between the measured osmolality and the calculated osmolality indirectly indicates presence of osmotically active substances other than Na+, urea, or glucose

24

osmolality

a physical property of a solution that is based on the concentration of solutes (millimoles) per kilogram of solvent (w/w); related to several changes in solution properties relative to pure water such as freezing point depression and vapor pressure decrease

25

osmolarity

a physical property of a solution that is based on the concentration of solutes reported in milliosmoles per liter (w/v); inaccurate in hyperlipidemia and hyperproteinemia, for urine specimens, and certain substances (alcohol or mannitol)

26

osmometer

operate by freezing point depression standardized using sodium chloride reference solutions; sample is supercooled to -7 degrees C and seeded to initiate freezing process; freezing point is measured reported as milliosmoles per kilogram

27

polydipsia

excessive water intake

28

tetany

irregular muscle spasms

29

neutral balance

intake = output

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positive balance

intake > output

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negative balance

intake < output

32

osmosis

movement of water between two compartments by a membrane permeable to water but not to solute

33

diffusion

movement of particles down a concentration gradient

34

active transport

movement of particles up a concentration gradient; requires energy

35

sodium

has a pulling affect on water; considerable more outside cells than inside cells so water is pulled out of cells into extracellular fluid; determines osmotic pressure of extracellular fluid

36

albumin

strongly pulls keeps water inside the vascular system; provides oncotic pressure, regulating hydration

37

osmolality increase

stimulates two responses that regulate water; hypothalamus stimulating thirst and posterior pituitary secretes ADH increasing plasma water

38

275-295 mOsm/Kgm

normal serum osmolality values

39

300-900 mOsm/Kgm

normal osmolality values 24 hour urine

40

1-3

urine to serum osmolality ratio

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<10-15 mOsm

Osmolality gap

42

calculated osmolality

uses glucose, BUN, and sodium (ECF) values

1.86 x Na + glucose/18 + BUN/2.8

43

<10-15 units

difference between calculated and determined osmolality

44

154 mEg/L

balance between cations and anions in the ECF

45

sodium

major (highest quantity) cations in the extracellular compartment

46

142 mEg/L

balanced sodium concentration

47

chloride

major anion in the extracellular compartment

48

105 mEg/L

balanced chloride concentration

49

135-145 mEg/L

sodium reference range

50

3.4-5.0 mEg/L

potassium reference range

51

98-106 mEg/L

chloride reference range

52

22-26 mEg/L

bicarbonate reference range

53

8.5-10.4 mg/dL

calcium reference range

54

1.8-3.6 mg/dL

magnesium reference range

55

3-4.5 mg/dL

phosphorus reference range

56

6-16 mom/L

anion gap reference range

57

increased

anion gap related to uremia/renal failure, ketoacidosis, starvation, alcohol/salicyclate OD, and interment error

58

decreased

anion gap related to hypoproteinemia and severe hypercalcemia

59

sodium and chloride

the most easily lost electrolytes

60

kidney

major regulator of body sodium

61

hypernatremia

caused by profuse sweating, high salt intake, and decrease in ADH

62

hyponatremia

caused by vomiting, diarrhea, and polyuria, or dilution due to water retention caused by edema and cardiac failure

63

potassium

major intracellular cation almost completely reabsorbed in proximal tubules and secreted in distal tubules

64

potassium

contracts the skeletal and cardiac muscles, intracellular volume, and hydrogen concentration

65

hyperkalemia

caused by intravenous infusion, renal failure, and DKA

66

hypokalemia

caused by starvation, alkalosis, and vomiting, diarrhea, and intestinal fistulas

67

chloride

significant in water distribution and osmotic pressure, is passively reabsorbed in ascending limb of loop of Henle and actively reabsorbed by pump

68

hyperchloremia

caused by dehydration, kidney diseases, and salicylate intoxication

69

hypochloremia

caused by vomiting, salt-losing nephritis, and metabolic acidosis

70

total carbon dioxide (Bicarb)

second most abundant anion in ECF

71

hypercapnia

caused by metabolic alkalosis due to vomiting and hypokalemia states

72

hypocapnia

renal diseases, diarrhea and respiratory alkalosis

73

magnesium

4th most abundant cation, 2nd most abundant intracellular cation (#1 skeleton, #2skeletal muscle, liver, and myocardium, #3 blood); functions as an activator or cofactor for more than 300 enzymes (glycolysis, trancellular ion transport, neuromuscular transmission, and carb, protein, lipid, and nucleic acid synthesis); absorbed in small intestine regulated by kidney's loop of Henle

74

hypomagnesemia

observed in hospitalized individuals in ICU, diuretics and digitalis, associated with acute infarctions

75

hypermagnesemia

caused by large dietary intake (antacids), renal failure, magnesium sulfate during surgery; toxic causes CNS-ECG changes, heart block, sedation, coma, respiratory depression or arrest

76

magnesium testing

nonhemolyzed samples from red top or LiHe tubes serum/plasma separated immediately

77

calcium

functions include bone structure, coagulation, muscle contraction, membrane permeability; regulated by PTH, vitamin D, and calcitonin

78

55%

percentage of calcium bound to albumin and other substances

79

45%

percentage of physiologically active form of calcium (ionized)

80

PTH

increases ionized calcium, decreases phosphate; secretion increases with decreasing ionized calcium concentrations; secretion is stopped with increases in Ca++; stimulates resorption of calcium from bone to serum and increases tubular kidney reabsorption of calcium; stimulates active vitamin D

81

vitamin D

increases calcium absorption in intestine and enhances the effect of PTH on bone resorption; increases phosphate

82

calcitonin

produced by parafollicular cells in thyroid gland and is secreted by increased blood calcium concentrations to decrease calcium levels, increase phosphate levels

83

hypocalcemia

caused by PTH and vitamin D deficiencies; causes increased neuromuscular irritability, tetany and/or convulsions

84

hypercalcemia

caused by hyperparathyroidism, various malignancy, and renal disease (glomerular filtration causing accumulation in blood)

85

ionized calcium

requires whole blood in heparinized sealed syringe or LiH; more sensitive and specific to calcium disorders

86

8.5-10.4 mg/dL

ionized calcium reference range

87

phosphate

major intracellular anion; 80% found in bone; blood concentrations regulated by kidney through excretion or reabsorption; blood Ph may be absorbed through diet, released from cells, and lost from bone

88

hypophosphatemia

seen in hospitalized patients: DKA, COPD, asthma, malignancy, inflammatory bowel disease, anorexia, and alcoholism, and sepsis, hyperparathyroidism (increased excretion), decreased intestinal absorption

89

hyperphosphatemia

caused by renal failure (decreased excretion), increased intake, increased release from cells; neonates especially susceptible due to underdeveloped PTH and vitamin D metabolism

90

phosphate

non-hemolyzed serum or LiH samples only

91

PTH

increases plasma calcium, increases plasma magnesium, and decreases phosphate

92

acidosis

associated with increased potassium

93

alkalosis

associated with decreased potassium

94

Ion selective electrodes (ISE)

method of measuring most electrolytes