Electrolytes, water homeostasis and associated disorders

Question 1

Electrolytes

Answer 1

Detection of sodium and potassium plasma levels are one of the most frequent tests undertaken
Common alteration, some can be significant and life-threatening, requiring immediate attention and treatment

Question 2

Water Homeostasis

Answer 2

Water makes up approx 60% of human body weight
Taken in and lost during daily activities
Water distribution - intracellular component, extracellular component

Question 3

Osmolality

Answer 3

A measure of osmotically active particles in solution
Dissolved components contribute to osmolality
Water will move from a region of low osmolality to a region. of high osmolalityly

Question 4

FLuid transfer

Answer 4

Fluctuation of water can impact osmolallitly of extrcellualr component
Water can pass feely between compartments
Movement of water can impact cell and therefore function
Range of electrolytes in different comparments

Question 5

Regulating. blood volume

Answer 5

Water deprivation - increased plasma osmolatilty, detected by osmorerecpetors in hypothalamus
Antiderietic Hormone (ADH) - activates receptors in kidney, increasing permeability of renal tububle to water
Maintaining osmolality will also impact total body volume

Question 6

Controlling body fluid volume

Answer 6

Key mechanism for controlling body fluid volume
Hypovolaemia - lowering of blood pressure

Question 7

Fluid and electrolyte status

Answer 7

Range of clinical situation associated with changes in electrolytes/fluid
Also important in primary care setting
Monitoring following treatments

Question 8

Artefacts

Answer 8

Certain tube types can contain anticoagulants that use sodium or potassium based salts - containing sample
Samples take from vein with IV drip

Question 9

Measurement

Answer 9

Sodium and potassium commonly measured using Ion - Selective Electrodes (ISEs) - Direct ISEs, Indirect ISEs, solvent exclusion effect