Fluids and Electrolytes

Question 1

What proportion of body weight is water?

Answer 1

45-65%

Question 2

____________ ________ comprises two-thirds of water weight.

Answer 2

Intracellular fluid

Question 3

Extracellular fluid makes up ____-______ of water weight.

Answer 3

One-third

Question 4

_________ is one quarter, and interstitial fluid is three quarters of the extracellular fluid.

Answer 4

Plasma

Question 5

Extracellular fluid loss may be due to acute ______ _____, vomiting, and diarrhoea.

Answer 5

Blood loss

Question 6

State two ways by which extracellular fluid can be gained.

Answer 6

IV fluid overload and heart failure

Question 7

What is the homeostatic response of changes in extracellular fluid?

Answer 7

Changes in plasma volume, or osmotic concentrations

Question 8

The concentration of solutes per kilogram of solvent (mOsm/kg H2O) is ____________.

Answer 8

Osmolality

Question 9

‘Normal’ plasma osmolality is 2__ - 295 mOsm/kg.

Answer 9

85

Question 10

__________ osmolality is from 300 - 900 mOsm/kg.

Answer 10

Urine

Question 11

_________, and its associated anions, account for most of the osmotic activity of plasma.

Answer 11

Sodium

Question 12

___________ is regulated by changes in water balance.

Answer 12

Sodium

Question 13

___________ is regulated by changes in sodium balance.

Answer 13

Volume

Question 14

Measurement of osmolality is done by osmometer, and based on freezing point or ___________ ______________.

Answer 14

Vapour depression

Question 15

State the formula for calculated osmolality.

Answer 15

2 x [Na+] + [urea] + [glucose]

Question 16

__________ _____ are caused by the difference between measured and calculated osmolality.

Answer 16

Osmolal gaps

Question 17

Osmolality - ___________ ___________ = osmolal gap

Answer 17

Calculated osmolality

Question 18

GFR Increases with volume expansion, and decreases with volume ___________.

Answer 18

Depletion

Question 19

What is the role of atrial natriuretic peptide?

Answer 19

Promotes sodium excretion by the kidney

Question 20

True or false: in water excess, ADH secretion and thirst are suppressed.

Answer 20

True

Question 21

Hypernatraemia occurs during _______ ___________.

Answer 21

Water depletion

Question 22

___________ dehydration can be caused by GI losses, inadequate fluid intake, etc..

Answer 22

Isotonic

Question 23

___________ dehydration results from diuretic drugs, osmotic diuresis, etc..

Answer 23

Hypertonic

Question 24

__________ dehydration can be derived from GI losses, and high-sodium sweat (as seen in cystic fibrosis).

Answer 24

Hypotonic

Question 25

Give two causes of high osmolality.

Answer 25

Hyperglycaemia and increased urea

Question 26

______________ are ions that are capable of carrying an electric charge, and may be positive or negative.

Answer 26

Electrolytes

Question 27

List four functions of electrolytes.

Answer 27

Volume and osmotic regulation (Na, K, and Cl) Acid-base balance (HCO3, K, Cl) Neuromuscular excitability (K, Ca, and Mg) Myocardial rhythm and contractility (K, Mg, and Ca)

Question 28

True or false: electrolytes are often measured in conjunction with sodium and urea.

Answer 28

True

Question 29

What is the plasma reference range for sodium?

Answer 29

135 - 145 mmol/L

Question 30

Hyponatraemia is decreased plasma _________.

Answer 30

Sodium

Question 31

Increased sodium loss may be due to _______________, potassium deficiency, diuretic use, ketonuria, prolonged D&V, or salt-losing nephropathy.

Answer 31

Hypoadrenalism

Question 32

__________________ may be due to hyperlipidaemia, or hyperproteinaemia.

Answer 32

Pseudohyponatraemia

Question 33

_______________ hyponatraemia may be attributed to sodium loss and water retention.

Answer 33

Hypoosmotic

Question 34

Isosmotic hyponatraemia is due to increased non-__________ cations, and may be observed in pseudohyponatraemia.

Answer 34

Sodium

Question 35

______________ hyponatraemia involves increased amounts of other solutes in the plasma.

Answer 35

Hyperosmotic

Question 36

_________________ is increased plasma sodium (>146 mmol/L).

Answer 36

Hypernatraemia

Question 37

True or false: hypernatraemia is always hyperosmolar.

Answer 37

True

Question 38

Increased intake or retention, such as _________________, or sodium bicarbonate excess, is also a factor of hypernatraemia.

Answer 38

Hyperaldosteronism

Question 39

<300 mOsm/kg may be observed in ____________ ____________.

Answer 39

Diabetes insipidus

Question 40

300 - 700 mOsm/kg indicates a ________ defect in ADH, osmotic diuresis, etc..

Answer 40

Partial

Question 41

>700 mOsm/kg indicates a loss of thirst, insensible loss of water, GI loss of ____________ fluid, and excess intake of sodium.

Answer 41

Hypotonic

Question 42

__________ syndrome involves excessive aldosterone.

Answer 42

Conn's

Question 43

Cushing's syndrome involves __________________.

Answer 43

Hypercortisolism

Question 44

True or false: lipaemia interferes with flame emission spectrophotometry.

Answer 44

True

Question 45

True or false: heparinised samples are not suitable for use in sodium measurement.

Answer 45

False

Question 46

Name a common electrochemical method of measuring electrolytes.

Answer 46

Iron selective electrodes (ISE)

Question 47

Outline the principle of iron selective electrodes.

Answer 47

Measures activity of electrolytes, in a defined volume of water. Charges are produced by having different ion concentrations on either side of the membrane. Two electrodes, a reference electrode and measuring electrode, are used. The difference in potential between electrodes is a reflection of the difference in ion activity, and is used to calculate a concentration, in mmol/L. Direct ISE uses an undiluted sample; indirect ISE used a diluted sample

Question 48

___________ ISE measurement is more accurate in pseudohyponatraemia, when hyperproteinaemia or hyperlipidaemia displace plasma water.

Answer 48

Direct

Question 49

State the principle of flame emission spectrophotometry.

Answer 49

When atoms of many metallic elements, especially Na and K, are given sufficient energy, they emit this energy at wavelengths; the energy comes from a flame, which excites the element, and they emit characteristic spectra

Question 50

Potassium is a major intracellular _________ in the body.

Answer 50

Cation

Question 51

lThe ___________ reference range of potassium is 3.5-5.0 mmol/L.

Answer 51

Serum

Question 52

What is the urine reference range for potassium?

Answer 52

30-100 mmol/day

Question 53

Potassium has major effects on contraction of skeletal and cardiac muscles, together with ________ ___________ ____________.

Answer 53

Resting membrane potential

Question 54

True or false: H+ concentration is not affected by potassium.

Answer 54

False

Question 55

______________ increases K+ excretion.

Answer 55

Aldosterone

Question 56

List two features, other than aldosterone, which regulate potassium secretion.

Answer 56

Insulin and pH

Question 57

True or false: hyperkalaemia is the most common electrolyte disturbance detected.

Answer 57

True

Question 58

List three symptoms of hyperkalaemia.

Answer 58

Mental confusion, bradycardia, and weakness

Question 59

Outline the first-used treatment for hyperkaelamia.

Answer 59

Infusion of insulin and glucose, to move potassium into cells

Question 60

State three causes of hyperkalaemia.

Answer 60

Renal failure, hypoaldosteronism, and use of diuretics.

Question 61

Sample haemolysis or _______________ may cause artifacts to appear in hyperkalaemia investigation.

Answer 61

Thrombocytosis

Question 62

Define hypokalaemia.

Answer 62

Serum potassium concentration of <3.5 mmol/L

Question 63

Symptoms of _____________ involve muscle weakness, irritability, and paralysis.

Answer 63

Hypokalaemia

Question 64

Pseudohypokalaemia may be observed in acute ______________.

Answer 64

Leukaemia

Question 65

List two causes of true potassium deficit.

Answer 65

Cushing's disease and acute tubular necrosis

Question 66

What is the treatment for hypokalaemia?

Answer 66

Potassium salts, and occasionally IV potassium

Question 67

True or false: serum levels of potassium tend to be lower than those of plasma.

Answer 67

False

Question 68

What is the method of choice in measuring potassium?

Answer 68

Iron selective electrodes

Question 69

____________ is the most abundant anion in extracellular fluid.

Answer 69

Chloride

Question 70

What is the serum (and plasma) reference range for chloride?

Answer 70

97-107 mmol/L

Question 71

What is the urine reference range for chloride?

Answer 71

110-250 mmol/day

Question 72

Changes in chloride concentration usually follow those of ______________.

Answer 72

Sodium

Question 73

If an _______-_______ ______________ is present, chloride can differentially diagnose.

Answer 73

Acid-base disturbance

Question 74

What specimen is used in testing the chloride of cystic fibrosis patients?

Answer 74

Sweat

Question 75

State a method of chloride quantification, other than iron selective electrodes.

Answer 75

Mercurimetric titration

Question 76

What is the chemical formula for bicarbonate?

Answer 76

HCO3-

Question 77

Bicarbonate is the second-most common _______ in extracellular fluid.

Answer 77

Anion

Question 78

What is the reference range (for serum and plasma) for bicarbonate?

Answer 78

24-27 mmol/L

Question 79

True or false: bicarbonate is most accurately quantified when the sample has been incubated at room temperature for one hour.

Answer 79

False

Question 80

To measure total CO2 (and thus bicarbonate), if the sample is _____________, CO2 is converted to HCO3-, followed by an enzymatic reaction.

Answer 80

Alkalinised

Question 81

CO2 converted to HCO3 - followed by an enzymatic reaction