Clinical Chemistries: Electrolytes Flashcards
What are electrolytes?
Ions
- anions (-)
- cations (+)
What are the major functions of electrolytes?
Maintain water balance, fluid osmotic pressure, normal muscle, and nerve function, and acid-base regulation
What are the commonly run in-house electrolytes tests?
Sodium
Potassium
Chloride
What are the commonly run send-out electrolytes tests?
Calcium
Phosphorus
Magnesium
What is bicarbonate?
not a true electrolyte
it is a blood buffer that maintains pH
What does Acid-Base Balance refer to?
The steady-state of the pH of the body
What is the normal pH?
7.35 to 7.45
Below 7.3=
Acidosis (excess H+)
Above 7.5=
Alkalosis (low H+)
What two systems work to regulate the pH in acid-base imbalance?
Respiratory and renal systems
Hypercapnia
Increases in CO2 in the body
What happens if the respiratory rate decreases?
Less CO2 is eliminated
What does an increase in partial pressure cause?
Acidosis
Hypocapnia
Decrease of CO2 in body
Decrease in PCO2 causes what?
Alkalosis
Metabolic acidosis or alkalosis
All other causes besides the respiratory system
Ketosis (acidosis)
Vomiting (Alkalosis)
Cations
Na+ K+ Ca++ Mg++ H+
Anions
Cl-
HCO3-
PO4
What important role does sodium play?
Water distribution and body fluid osmotic pressure maintenance
What tube do you not use when running sodium?
Heparin
Conditions associated with hypernatremia
Water deprivation
Hyperventilation
Osmotic diuresis
Conditions associated with hyponatremia
GI disorders
Ketonuria
Hypoadrenocorticism
Congestive Heart Failure
Potassium
Major intracellular cation
What is potassium important in?
Normal muscular function Respiration Cardiac function Nerve impulse transmission Carbohydrate metabolism
What is preferred when running potassium?
Plasma
Potassium may be released during the clotting
What do you avoid when collecting blood for potassium?
Hemolysis
Releases Potassium
Conditions associated with hyperkalemia
Metabolic acidosis
Urinary tract infection
Renal Insufficiency
Conditions associated with hypokalemia
Anorexia
Ketonuria
Diuresis
Chloride
Predominant extracellular anion
What does chloride play an important role in?
Maintenance of water distribution
Osmotic pressure
normal anion/cation ratio
Hyperchloremia
Elevated chloride levels
Hypochloremia
Decreased chloride levels
What interferes with the results of chloride?
Hemolysis and prolonged storage
Bicarbonate (HCO3)
The second most common anion of plasma
What does bicarbonate help maintain?
Acid-base (pH) balance
What helps regulate bicarbonate levels?
The Kidney
What is bicarbonate levels frequently estimated from
CO2 levels
What percent of bicarbonate levels are from the total CO2 levels measured?
95%
What is found in more than 50% of bones?
Magnesium
What can result from the imbalance of the Mg/Ca ratio?
Muscular tetany from the release of acetylcholine
What are the two species that show clinical signs of hypomagnesemia?
Cattle and Sheep
What may decrease magnesium results?
Anticoagulants other than heparin
What is found in 99% of bones?
Calcium
What are the functions of the remaining 1% of the calcium in the body?
Maintenance of neuromuscular excitability and tone
Activity of enzymes
Inorganic ion transfer across cell membranes
Facilitates blood coagulation
The concentrations of calcium are inversely related to what concentrations?
Inorganic phosphorus
When collected a blood sample for calcium levels what should you not use?
EDTA
Oxalate or citrate anticoagulants
More than 80% of inorganic phosphorus is found where?
In the bones
What are the functions of the remaining 20% inorganic phosphorus?
Energy storage, release, and transfer
Involvement in the carbohydrate metabolism
What is inorganic phosphorus needed to make?
Nearly every type of protein in the body
Inorganic PO4 in plasma or serum becomes what in red blood cells?
Organic PO4
What will falsely elevate inorganic phosphorus levels?
Hemolysis
Anion Gap: Normal circumstances
The same number of cations and anions
Any difference is called the anion gap
What is the Anion Gap calculated from?
Measured electrolyte values
What is the formula to calculate Anion Gap
(Na+ + K+) - (Cl- + HCO3)
In what cases will you see an increase in the anion gap?
Lactic acidosis
Renal failure
Diabetic ketoacidosis
In what cases will you see a decrease in the anion gap?
Hypoalbuminemia
