Topic 5 Electrolytes Flashcards by Jacquie Swenson

What % of the body is made up of total body water?

60%

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Gamblegram

-shows the most common anions and cations in plasma

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How is sodium added and removed from the body?

Water follows by osmosis

Added to body:
-food, fluid therapy

Removed from body:
-urine, feces, abnormal GI losses, sweat

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Sodium concentration in ECF
regulation

-regulated by the body detecting osmolality

Increased osmolality
-thirst
-ADH secretion –> free water reabsorption in the kidney

Decreased osmolality:
-inhibition of thirst
-ADH inhibiton–> free water excretion in the kidney

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Hypernatraemia

-due to free water deficit

Causes:
-Excessive hypotonic/free water loss with inability to replace via drinking

oRenal loss = diabetes insipidus

-Inappropriate lack of ADH effect on kidney

-Central = ADH not secreted

-Nephrogenic = ADH receptor not present or not functional

-GI losses in some species – primarily calves

-Most species GI losses are isotonic

-Respiratory losses (panting)

-Excessive sweating

*Lack of water access

*Hypodipsia/adipsia
Salt toxicity

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How to manage hypernatraemia

Provide free water carefully
*If the hypernatraemia has been chronic, neurons generate idiogenic osmoles to make ICF osmolality = ECF osmolality

oAttempt to reduce ECF [Na+ ] by 0.5-1.0 mmol/L/hour

oDone by calculating free water deficit – in critical care textbook

*Be more careful with more severe (> 165 mmol/L)

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Pseudohyponatraemia

Measurement error – serum biochemical analysers with indirect technique inaccurate with abnormal serum protein/lipid concentrations

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Hyponatraemia

-free water excess

-cannot lose salt out of the body without water loss

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Causes of free water excess

Hypovolaemia
Euvolemia
Hypervolaemia

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Hypovolaemia

*Isotonic fluid losses (e.g., GI, urinary, burns, effusions) → nonosmotic ADH release and thirst → free water gain/reabsorption

*This is how hypoadrenocorticism causes hyponatraemia (renal fluid losses)

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Euvolemia

*Psychogenic polydipsia/water toxicity
*Hypotonic fluid administration
*Syndrome of inappropriate ADH (SIADH)

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Hypervolaemia

*Decreased effective circulating volume despite expanded total ECF volume
*Congestive heart failure
*Severe liver/renal disease

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Hyponatremia management

-typically, minimal clinical signs if chronic, neurological signs if acute

-increasing [Na] too quickly can cause neuronal shrinkage and secondary demyelination

if acute:
-give hypertonic saline +/- diuretics to increase [Na] and control signs

if chronic:
-increase [Na+] very slowly (no more than 0.5 mmol/L/hour)

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What is movement of potassium (ECF to ICF) promoted by?

Insulin
Catecholamines
Alkalosis

long term regulation:
-by aldosterone

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Hyperkalaemia causes:

1-Excessive intake alone rarely sufficient to cause hyperkalaemia

2-Decreased excretion
-decreased renal perfusion
-renal failure
-hypoaldosteronism
-urinary obstruction or rupture

3- Shift from ICF → ECF
-massive cellular necrosis
-acidosis
-thrombocytosis, haemolysis in animals with high RBC potassium
-insulin/catecholamine deficiency

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How to manage hyperkalaemia?

Altered membrane potential is cardiotoxic → arrhythmias (usually bradyarrhythmias)

*Give IV calcium gluconate to correct cardiomyocyte function

Short term
*Dilute with IV fluids
*Cause ECF → ICF shift with insulin (+ glucose) or catecholamine (terbutaline)

Longer term
*Facilitate excretion

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Hypokalaemia causes?

-prolonged anorexia
-decreased intake in combination with increased excretion

Increased excretion:
-polyuria of any cause (body can not absorb it enough in the distal tubule)
-excessive GI loss-vomiting and diarrhoea

Shift from ECF–> ICF
-alkalosis
-insulin/catecholamine excess

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How to manage Hypokalaemia?

-causes muscle weakness if severe

-occasionally arrhythmias can contribute to worsening polyuria

-supplementation
(intravenous or oral); depends on underlying disease, concurrent treatments.

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Chloride typically changes with ___

Na+

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Hypochloraemia

-increased free water can cause hypochloraemia
-decreased free water can cause hyperchloraemia

but.. chloride can change independent of free water (and therefore, sodium)

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How is chloride “corrected” for free water balance

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Hyperchloraemia is associated with….

metabolic acidosis

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Hypochloraemia is associated with….

metabolic alkalosis

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Arterfactial Hyperchloraemia

*Bromide causes severe artefactual hyperchloraemia
*Cannot reliably assess chloride concentration in patients receiving bromide

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Acid-Base Analysis to assess the acid-base status of an animal

1.Assess the pH 2.Assess the respiratory contribution 3.Assess the metabolic contribution 4.Determine on primary process with or without compensation, vs mixed disorder 5.Determine DDx for each primary process *If metabolic acidosis – calculating anion gap will assist in this

Acidaemia

pH below normal

Alkalaemia

pH is above normal

Low CO2

oRespiratory alkalosis oHypocapnia oHyperventilation

High CO2

oRespiratory acidosis oHypercapnia oHypoventilation

Increased HCO3 -

metabolic alkalosis -remember that bicarb is a buffer**

Decreased HCO3-

metabolic acidosis

What species is poor at compensation?

cats poor at resp and metabolic compensation

What can cause respiratory acidosis?

synomonous with hypoventilation -airway obstruction -neuromuscular disease/weakness -severe pulmonary parenchymal disease -something restricting lung expansion (pleural space disease, chest wall disease, severe abdominal distenstion) -rebreathing -increase in CO2 production with fixed minute ventilation -compensation for primary metabolic alkalosis

Respiratory alkalosis = hyperventilation causes?

*Pulmonary parenchymal disease – rule this out first *Excitement/stress *Pain *Exercise *Fever *Hypotension/shock *Compensation for primary metabolic acidosis (pH will be acidaemic)

Metabolic Alkalosis differentials

-Acid loss with HCO3 - retention -Gastric acid loss -GI obstruction, e.g., foreign body, abomasal displacement -Functional decreased gastric emptying -Gastric suctioning -Renal acid loss -Loop diuretics -Excessive aldosterone *HCO3 - administration *Compensation for primary respiratory acidosis (pH will be acidaemic)

What can cause metabolic acidosis that lead to additional unmeasured anions?

-Lactate -Uraemic acids -Ketoacids -Ethylene glycol metabolites

The intracellular fluid compartment a.Constitutes 1/3 of total body water and has a high sodium concentration b.Constitutes 2/3 of total body water and has a high sodium concentration c.Constitutes 1/3 of total body water and has a high potassium concentration d.Constitutes 2/3 of total body water and has a high potassium concentration

Constitutes 2/3 of total body water and has a high potassium concentration

Hyperkalaemia is most likely to result from ... a.Polyuria b.Oliguria c.Vomiting d.Diarrhoea

Oliguria

Hyperkalaemia could be treated with administration of ... a.Glucagon b.Cortisol c.Insulin d.Growth hormone

c.Insulin

A blood gas panel performed on a dog. This is most likely consistent with?

Ethylene glycol toxicity

This is most consistent with ... a.Diarrhoea b.Airway obstruction c.Renal failure d.Pain

airway obstruction

The formula for calculating the anion gap is ...

(Na+ + K+) – (Cl- + HCO3-)

Aldosterone deficiency will result in ... a. Hypervolaemia, with subsequent antidiuretic hormone (ADH) inhibition b.Hypovolaemia, with subsequent antidiuretic hormone (ADH) inhibition c.Hypovolaemia, with subsequent antidiuretic hormone (ADH) secretion d.Hypervolaemia, with subsequent antidiuretic hormone (ADH) secretion

Hypovolaemia, with subsequent antidiuretic hormone (ADH) secretion

Acute ingestion of a large volume of fresh water would result in ... a.Cardiac arrhythmia b.Osmotic demyelination c.Muscle weakness d.Cerebral oedema

d.Cerebral oedema

Appropriate compensation for a primary metabolic acidosis involves ... a.Increasing the anion gap b.Hypercarbia c.Hyperventilation d.Increased CO2

c.Hyperventilation

The most accurate measure of all ECF buffer systems is the ... a.Bicarbonate concentration b.Base excess c.pH d.pKa

b.Base excess

A 9 week old female intact Maltese cross presents for a 2-3 day history of severe vomiting and haemorrhagic diarrhoea (hematochezia). On presentation she is collapsed in shock. A point-of-care test is positive for canine parvovirus. Results of a point-of-care venous blood gas and electrolyte panel are shown below, Select the pathophysiology that best explains the hyponatremia:

Nonosmotic ADH release due to hypovolemia

A 9 week old female intact Maltese cross presents for a 2-3 day history of severe vomiting and haemorrhagic diarrhoea (hematochezia). On presentation she is collapsed in shock. A point-of-care test is positive for canine parvovirus. Results of a point-of-care venous blood gas and electrolyte panel are shown below, Select the most accurate description of the acid-base disorder:

Mixed disorder (primary metabolic acidosis [high AG] with primary respiratory acidosis)

Increased gastrointestinal losses with decreased intake

high anion gap metabolic acidosis causes:

Lactic acidosis Uraemia Ketoacidosis (diabetes/starvation) Toxins (ex. ethylene glycol)

Which body fluid compartment is the largest? a) Plasma b) Interstitial fluid c) Intracellular fluid d) Extracellular fluid

Intracellular fluid

Which cation is the major intracellular ion? a) Na⁺ b) K⁺ c) Ca²⁺ d) Mg²⁺

K+

Which cation is the major extracellular ion? a) K⁺ b) Na⁺ c) Cl⁻ d) HCO₃⁻

Na+

Which compartment represents ~25% of extracellular fluid? a) Intracellular fluid b) Plasma c) Interstitial fluid d) Bone water

Plasma

Which physiological principle ensures water movement between compartments? a) Hydrostatic pressure b) Osmosis c) Diffusion d) Active transport

Osmosis

What maintains electroneutrality in each fluid compartment? a) Sodium-potassium pump b) Equal number of cations and anions c) Albumin concentration d) Osmotic pressure

Equal number of cations and anions

What does the Gamblegram illustrate? a) Differences in osmolality between ICF and ECF b) Common anions and cations in plasma c) Role of glucose in water balance d) Plasma protein buffering

Answer: b) Common anions and cations in plasma

What are UA and UC in the Gamblegram? a) Unmeasured acids and bases b) Unmeasured anions and cations c) Urinary acids and cations d) Unique albumin and creatinine

Unmeasured anions and cations

Sodium concentration in plasma usually reflects changes in: a) Sodium quantity b) Water balance c) Protein concentration d) Potassium balance

Water balance

What happens if sodium is added to the ECF? a) [Na⁺] increases b) Water shifts into cells c) ECF volume expands d) ICF volume expands

ECF volume expands

What is the main regulator of sodium excretion? a) Catecholamines b) Renin-angiotensin-aldosterone system (RAAS) c) Parathyroid hormone d) Glucocorticoids

b) Renin-angiotensin-aldosterone system (RAAS)

Which hormone promotes sodium and water excretion when ECF volume is high? a) ADH b) Aldosterone c) Atrial natriuretic peptide (ANP) d) Cortisol

c) Atrial natriuretic peptide (ANP)

Which system may be inappropriately activated in heart failure? a) RAAS b) ANP secretion c) Sympathetic inhibition d) ADH inhibition

a) RAAS

Hyponatraemia most commonly results from: a) Sodium loss alone b) Water gain relative to sodium c) Potassium depletion d) Low aldosterone

b) Water gain relative to sodium

Hypernatraemia most commonly results from: a) Sodium intake alone b) Water deficit c) Potassium excess d) High aldosterone

b) Water deficit

Which hormone is secreted in response to increased plasma osmolality? a) Aldosterone b) Cortisol c) ADH d) ANP

c) ADH

Non-osmotic ADH release occurs in response to: a) Hyponatraemia b) Hypovolaemia c) Hypernatraemia d) Hyperkalaemia

b) Hypovolaemia

Chronic hypernatraemia is dangerous to correct quickly because of: a) Hypotension b) Osmotic demyelination c) Cerebral oedema d) Nephrocalcinosis

c) Cerebral oedema

A calf with watery diarrhoea is most likely to develop: a) Hypernatraemia b) Hyponatraemia c) Hypokalaemia d) Hyperkalaemia

a) Hypernatraemia

Hyponatraemia with high glucose is termed: a) Pseudohyponatraemia b) Hypervolemic hyponatraemia c) SIADH d) Hypovolaemic hyponatraemia

a) Pseudohyponatraemia

Which disorder is linked to free water intoxication? a) Hypernatraemia b) Hyponatraemia c) Hyperkalaemia d) Hypokalaemia

b) Hyponatraemia

In hyponatraemia, rapid correction risks: a) Cardiac arrhythmias b) Central pontine myelinolysis c) Cerebral oedema d) Seizures

b) Central pontine myelinolysis

Major intracellular cation is: a) Sodium b) Potassium c) Chloride d) Calcium

Potassium

Which has the strongest effect on ECF potassium concentration? a) Total potassium intake b) Sodium balance c) Movement between ICF and ECF d) Serum albumin

Movement between ICF and ECF

Which promotes movement of potassium into cells? a) Acidosis b) Insulin c) Hypertonicity d) Cell necrosis

b) Insulin

Long-term potassium regulation is via: a) Insulin b) Catecholamines c) Aldosterone d) ADH

c) Aldosterone

Which is NOT a common cause of hyperkalaemia? a) Renal failure b) Addison’s disease c) Urinary obstruction d) Psychogenic polydipsia

d) Psychogenic polydipsia

First-line emergency therapy for hyperkalaemia-induced arrhythmias is: a) Insulin b) IV calcium gluconate c) Glucose infusion d) Loop diuretics

b) IV calcium gluconate

Which is a cause of hypokalaemia? a) Urinary obstruction b) Addison’s disease c) Vomiting d) Acidosis

c) Vomiting

Which clinical sign is most associated with severe hypokalaemia? a) Muscle weakness b) Seizures c) Polyuria d) Hypertension

a) Muscle weakness

Which therapy corrects hypokalaemia? a) IV saline b) Oral or IV potassium supplementation c) IV calcium gluconate d) Sodium bicarbonate

b) Oral or IV potassium supplementation

Hypochloraemia is usually associated with: a) Metabolic acidosis b) Metabolic alkalosis c) Respiratory acidosis d) Respiratory alkalosis

b) Metabolic alkalosis

Hyperchloraemia is usually associated with: a) Metabolic acidosis b) Metabolic alkalosis c) Respiratory acidosis d) Respiratory alkalosis

Answer: a) Metabolic acidosis

Which drug can cause artefactual hyperchloraemia? a) Bromide b) Furosemide c) Digoxin d) Mannitol

Bromide

Corrected chloride is useful to: a) Detect pseudohyponatraemia b) Distinguish free water vs chloride abnormality c) Calculate anion gap d) Diagnose SIADH

b) Distinguish free water vs chloride abnormality

Primary buffer system in blood is: a) Phosphate b) Bicarbonate c) Haemoglobin d) Albumin

b) Bicarbonate

Respiratory acidosis results from: a) Hyperventilation b) Hypoventilation c) Excess HCO₃⁻ loss d) Diarrhoea

b) Hypoventilation

Respiratory alkalosis results from: a) Hyperventilation b) Hypoventilation c) Vomiting d) Addison’s disease

a) Hyperventilation

Which species has poor metabolic compensation for acid–base disturbances? a) Dogs b) Cats c) Horses d) Cattle

Cats

Anion gap is calculated as: a) (Na⁺ – Cl⁻) b) (Na⁺ + K⁺) – (Cl⁻ + HCO₃⁻) c) (Cl⁻ + HCO₃⁻) – (Na⁺ + K⁺) d) (HCO₃⁻ – Na⁺)

Answer: b) (Na⁺ + K⁺) – (Cl⁻ + HCO₃⁻)

Increased anion gap metabolic acidosis is caused by: a) Vomiting b) Uraemia c) Hypoventilation d) SIADH

b) Uraemia

Normal anion gap metabolic acidosis is caused by: a) Ketoacidosis b) Lactic acidosis c) Diarrhoea d) Ethylene glycol

Diarrhoea

Which acid–base disorder is associated with gastric outflow obstruction? a) Respiratory acidosis b) Respiratory alkalosis c) Metabolic acidosis d) Metabolic alkalosis

d) Metabolic alkalosis

Which condition causes respiratory acidosis? a) Pleural effusion b) Psychogenic polydipsia c) Hyperventilation d) Fever

a) Pleural effusion

Treatment of metabolic acidosis with high anion gap typically involves: a) Bicarbonate supplementation b) Treating the underlying cause c) 0.9% NaCl infusion d) Loop diuretics

b) Treating the underlying cause

Topic 5 Electrolytes Flashcards

(96 cards)