Clinpath P2 Notes Water & Electrolytes PDF

Explain how to interpret laboratory results in the context of the animal’s CLINPATH P2 NOTES PPT clinical presentation. Water & Electrolytes...

Explain how to interpret laboratory results in the context of the animal’s CLINPATH P2 NOTES PPT clinical presentation. Water & Electrolytes Water and Electrolytes in the Body Discuss the key functions of water and electrolytes in the body. Fluid Balance: Explain maintaining water and electrolyte balance crucial for animal health. ❖ Proper water and electrolyte balance ensures that the body's Describe how do the kidneys regulate water and electrolyte balance. fluids are distributed and maintained in the correct compartments (intracellular, extracellular, and intravascular). Discuss the roles do hormones such as aldosterone and antidiuretic hormone (ADH) play in this process. Blood Pressure Regulation: Discuss how the various organs contribute to maintaining water and ❖ Controls blood volume and pressure. electrolyte homeostasis. Discuss the major electrolytes in the body, and what are their primary Nutrient and Waste Transport: functions (e.g., sodium, potassium, chloride, bicarbonate, calcium, ❖ Facilitates movement of substances in and out of cells. magnesium). Explain how do these electrolytes contribute to cellular functions and overall Acid-Base Balance: homeostasis. ❖ Regulates pH levels in the body. Discuss the causes and consequences of dehydration and overhydration in Cellular Function: animals. ❖ Supports nerve and muscle activities. Discuss common disorders related to water and electrolyte imbalance. Temperature Regulation: Differentiate and discuss the imbalances in specific electrolytes (e.g., ❖ Helps manage body temperature through sweating and hyperkalemia, hypokalemia, hypernatremia, hyponatremia) manifest evaporation. clinically. Total Body Water (TBW) Differentiate and describe the common clinical signs and symptoms of electrolyte imbalances in different species. ❖ makes up about 60% of body weight and helps maintain Discuss key clinical signs to look for when suspecting water and electrolyte balance in the body. imbalances. Fluid balance is achieved when fluid input equals fluid output, Discuss diagnostic tests are commonly used to assess water and electrolyte keeping fluid volumes stable. balance (e.g., blood gas analysis, serum electrolyte levels, urinalysis). TBW is divided into two main compartments: ❖ Intracellular Fluid (ICF): about two-thirds of the body water is  Source: Produced by the adrenal cortex. found within the cells  Function: Promotes sodium reabsorption and potassium ❖ Extracellular Fluid (ECF): all water that is not in the cell. excretion in the kidneys' distal tubules and collecting ❖ Interstitial fluids ducts. ❖ Intravascular fluids (Plasma Volume) ❖ Transcellular fluids RAAS (Renin-Angiotensin-Aldosterone System): Metabolic processes control the movement of electrolytes between these compartments.  Renin: Released by the kidneys in response to low blood pressure or low sodium levels. Renin converts Water is crucial in aiding temperature regulation and waste angiotensinogen (from the liver) into angiotensin I. removal, while electrolytes help balance pH levels and blood pressure. Overall, this balance is key to growth, energy, immune  Angiotensin II: Formed from angiotensin I by the action of function, and preventing health issues. angiotensin-converting enzyme (ACE). It causes blood vessels to constrict (increase blood pressure) and stimulates KIDNEYS the release of aldosterone and ADH. 1. Filtration: Blood is filtered in the kidneys, creating a fluid  Aldosterone: Acts to increase sodium reabsorption and that contains water, electrolytes, and waste. water retention, further elevating blood pressure and volume. 2. Reabsorption: As this fluid moves through kidney tubules, water and electrolytes are reabsorbed back into the bloodstream based on the body’s needs. 3. Hormonal Regulation 4. Excretion: The kidneys excrete excess water and electrolytes in the urine, helping to balance fluid levels and maintain stable internal conditions. Hormonal Regulation: ADH (Antidiuretic Hormone):  Source: Produced by the hypothalamus and released from the posterior pituitary gland.  Function: Increases water reabsorption in the kidneys' collecting ducts. This makes the urine more concentrated and helps the body conserve water when needed, which helps maintain blood volume and pressure. Aldosterone: ANP (Atrial Natriuretic Peptide): electrolytes, the kidneys can dilute the urine to excrete them.  Source: Released by the atria of the heart in response to high blood pressure. d) Acid-Base Balance - The kidneys help maintain the  Function: Reduces sodium and water reabsorption in the pH balance by excreting hydrogen ions and kidneys, increasing urine production and decreasing blood reabsorbing bicarbonate from the urine, which volume and pressure. indirectly affects electrolyte balance. Parathyroid Hormone (PTH): e) Hormonal Regulation - The kidneys respond to Source: Produced by the parathyroid glands. hormones like antidiuretic hormone (ADH) and Function: Increases calcium reabsorption in the kidneys and aldosterone. Through these mechanisms, the kidneys promotes the conversion of vitamin D to its active form, which ensure that water and electrolyte levels remain within enhances calcium absorption from the intestines. a narrow range, which is vital for normal cellular function, blood pressure regulation, and overall homeostasis. The Role of Organs in Water and Electrolyte Homeostasis LIVER: KIDNEYS: a) Production of Plasma Proteins - The liver produces  The primary regulators of water and electrolyte balance. proteins such as albumin, which helps maintain blood a) Filtration - The kidneys filter blood through their osmotic pressure. nephron units, removing waste products and excess substances while retaining essential nutrients and b) Metabolism of Hormones - The liver metabolizes and electrolytes. clears various hormones that are involved in fluid and electrolyte regulation, including those produced by the b) Selective Reabsorption - After filtration, the kidneys kidneys and adrenal glands. This helps modulate the reabsorb water and electrolytes as needed. This effects of these hormones on water and electrolyte selective reabsorption allows the body to retain balance. necessary substances and excrete excess amounts, maintaining balance. c) Synthesis of Angiotensinogen - The liver produces angiotensinogen, a precursor to angiotensin, which is c) Regulation of Urine Output - The kidneys adjust urine involved in the renin-angiotensin-aldosterone system production based on the body’s needs. If the body is (RAAS). This system regulates blood pressure and fluid dehydrated or has high electrolyte levels, the kidneys balance by influencing kidney function. can concentrate urine to conserve water and electrolytes. Conversely, if there is excess water or d) Detoxification and Processing - The liver processes various substances that can affect fluid and electrolyte  balance, including drugs and metabolic waste products. Its Primary Functions: detoxification role helps maintain overall metabolic o Regulates fluid balance: Sodium helps control the homeostasis. volume of fluids in the body. o Contributes to nerve impulse transmission and muscle contraction. ELECTROLYTES o Assists in the maintenance of blood pressure. Electrolytes are electrically charged minerals or compound that Cellular Functions and Homeostasis: are essential for cell metabolic functions. Essential electrolytes o Sodium ions are key in the function of the sodium- include sodium (Na+), potassium (K+), chloride (Cl-), and potassium pump (Na⁺/K⁺ pump), which helps bicarbonate (HCO3) Hence, diseases and conditions that can maintain cell membrane potential and proper change the concentration of these electrolytes will result in an cellular function. imbalance of these ions between the ECF and ICF, and will lead o Sodium levels in the body are tightly regulated by to subsequent pathologic states that causes improper function of the kidneys, hormones (like aldosterone), and different systems. various osmoreceptors to ensure homeostasis. Potassium (K⁺) - The principal cation for intracellular fluid (ICF). Primary Functions: o Vital for nerve function and neuromuscular contraction. o Helps regulate the heartbeat. o Assists in maintaining cellular fluid balance and osmotic equilibrium. Cellular Functions and Homeostasis: o Potassium is crucial for the Na⁺/K⁺ pump, which helps maintain a proper electrochemical gradient across cell membranes. o It is involved in creating action potentials in nerve Sodium (Na⁺) cells and muscle cells, including cardiac muscle. o The kidneys also play a key role in regulating - The primary cation in extracellular fluid (ECF). potassium levels under the influence of aldosterone. Chloride (Cl⁻) Primary Functions: o Essential for bone and teeth formation. o Critical for blood clotting. o Important for muscle contraction and nerve ❖ the principal anion in extracellular fluid (ECF). signaling. Cellular Functions and Homeostasis: Primary Functions: o Calcium ions are key in signal transduction o Helps maintain fluid balance and osmotic pressure. pathways. For instance, they act as second o Assists in the production of hydrochloric acid (HCl) messengers in many cellular processes. in the stomach, which is essential for digestion. o They are involved in synaptic transmission at nerve Cellular Functions and Homeostasis: terminals and muscle cell contractions. o Chloride ions help maintain electrical neutrality in o The parathyroid hormone (PTH), calcitonin, and the body by balancing positive charges from other active vitamin D regulate calcium levels in the electrolytes like sodium and potassium. blood. o Bicarbonate and chloride exchange across cell o Calcium is essential for the ossification of bone, membranes helps regulate acid-base balance. calcification of cartilage, regulation of skeletal and cardiac muscle tone, coagulation of blood, and Bicarbonate (HCO₃⁻) maintenance of osmotic pressure and ph. o Calcium metabolism is under the control of the ❖ An anion found in extracellular fluids (ECF). parathyroid gland, and vitamin D is necessary for its Primary Functions: deposition in cartilage and bone. o Acts as a buffer to maintain the pH of blood and Magnesium (Mg²⁺) other fluids within a narrow range. Cellular Functions and Homeostasis: ❖ A major cation and found in intracellular fluid (ICF). o Bicarbonate is part of the bicarbonate buffer system, which is one of the major systems Primary Functions: regulating blood pH. o Cofactor for numerous enzyme reactions. o It works with other buffers and respiratory/renal o Important for ATP production and utilization. mechanisms to correct pH imbalances and o Helps stabilize DNA and RNA structures. maintain acid-base homeostasis. Cellular Functions and Homeostasis: o Magnesium is involved in over 300 enzymatic Calcium (Ca²⁺) reactions, including those crucial for energy production, DNA synthesis, and repair. ❖ A cation found in extracellular fluids (ECF).  o It also plays a role in nerve transmission and b) Kidney Dysfunction: If the kidneys are not functioning muscle contraction. properly, they may fail to conserve water and electrolytes, o The kidneys aid in maintaining magnesium balance leading to dehydration. in the body. c) Inadequate Nutrient Intake: Lack of essential nutrients, DEHYDRATION AND OVERHYDRATION IN ANIMALS particularly those that influence fluid balance (like sodium and potassium), can contribute to dehydration. DEHYDRATION: Consequences: Dehydration occurs when an animal loses more fluids than it takes in, leading to a deficit in body fluids. a) Electrolyte Imbalance: Dehydration can disrupt the balance of electrolytes, which are crucial for nerve and muscle function. b) Hypovolemic Shock: Severe dehydration can lead to a dangerous drop in blood volume, causing shock. c) Organ Failure: Prolonged dehydration can damage organs, particularly the kidneys, and may lead to kidney failure. OVERHYDRATION (WATER INTOXICATION): Overhydration occurs when an animal takes in more water than the body can excrete, leading to an excess of water in the body. Causes: 1) Excessive Water Intake: Consuming an excessive amount of water in a short period can overwhelm the kidneys' Causes: ability to excrete it, leading to an imbalance in electrolytes. a) Inadequate Water Intake: Not drinking enough water to meet the body's needs can lead to dehydration. 2) Impaired Kidney Function: If the kidneys are not functioning properly, they may be unable to efficiently excrete excess water, resulting in fluid accumulation.  3) Electrolyte Imbalance: Overhydration can dilute electrolytes in the body, particularly sodium, leading to a COMMON DISORDERS RELATED TO ELECTROLYTE condition known as hyponatremia. This imbalance can IMBALANCE disrupt cellular function and fluid distribution. 4) Fluid Therapy: Incorrect administration of intravenous fluids, especially if given too rapidly or in excessive amounts, can lead to overhydration. Consequences: 1) Electrolyte Imbalance: Excessive water intake can dilute electrolytes, particularly sodium, leading to hyponatremia. This can disrupt cellular function and cause neurological symptoms like confusion, seizures, or even coma. 2) Cellular Swelling: Diluted electrolytes can cause cells to swell, particularly in the brain, leading to increased intracranial pressure and potential brain damage. 3) Edema: Fluid accumulation in tissues, or edema, can occur, causing swelling in various parts of the body. This can affect normal organ function and overall health. 4) Gastrointestinal Distress: Animals may experience nausea, vomiting, or diarrhea as the body tries to manage excessive fluid intake. 5) Disorientation and Behavioral Changes: Neurological effects from electrolyte imbalances can lead to behavioral changes, disorientation, or lethargy. 6) Kidney Strain: Excessive fluid can overwhelm the kidneys, impairing their ability to excrete fluids and maintain electrolyte balance, potentially leading to kidney damage. KEY CLINICAL SIGNS DIAGNOTIC TESTS COMMONLY USED 1) Serum Electrolyte Panel 2) Blood Gas Analysis 3) CBC 4) Urinalysis  Explain the acid-base imbalances affect the function of different organ systems in animals, acute and chronic state. Acid-Base Balance Regulation System Importance of Acid-Base Balance 1. Homeostasis and Enzyme Function: o pH and Homeostasis: tightly regulated within a narrow range (typically 7.35 to 7.45 in blood). o Enzyme Activity: highly sensitive to pH changes. Slight alterations in pH can reduce enzyme activity / denature enzymes. 2. Cellular Function and Metabolism: ACID-BASE BALANCE o Cell Membrane Integrity: ensure stability and function Discuss the importance of acid-base balance. of cell membranes. Describe how do acid-base disturbances affect animal health o Metabolic Reactions: ensure metabolic reactions can proceed efficiently without leading harmful changes in Explain the components of the body's acid-base regulation system? pH. Explain the Henderson-Hasselbalch equation used in understanding acid- 3. Oxygen Transport: base balance. o Hemoglobin Function: pH influences the binding and Describe and differentiate laboratory parameters used to assess acid-base release of oxygen by hemoglobin. o Carbon Dioxide Transport: as bicarbonate, ensures status (e.g., pH, pCO2, HCO3-)? efficient CO2 transport and elimination. Discuss how are these parameters measured in a clinical setting. 4. Nervous System Function o Neural Activity: highly sensitive to pH changes. Discuss and differentiate the four primary acid-base disorders (metabolic 5. Cardiovascular Function: acidosis, metabolic alkalosis, respiratory acidosis, respiratory alkalosis). o Heart Function: acid-base disturbances significantly impact the heart. Enumerate and discuss common causes of each type of acid-base disorder in veterinary patients. o Vascular Tone: pH influences the vasoconstriction and vasodilation of blood vessels. Explain common clinical signs and symptoms of acid-base disturbances 6. Electrolyte Balance: Explain how is the correct interpretation of acid-base disturbances. o Electrolyte Homeostasis: acid-base balance affects electrolyte balance (vice versa). Explain the importance of compensatory mechanisms in acid-base balance. 7. Compensation and Adaptation:  o Buffer, Respiratory, Renal Compensations: systems Terminologies to Remember: vital in regulating changes in acid-base to maintain pH in normal levels.  Acid: donate hydrogen ions to a solution 8. Clinical Significance:  Base: accept and bind hydrogen ions from a solution o Diagnosis & Treatment: essential for diagnosing and  Acidemia: below pH normal range treating acid-base balance disorders.  Alkalemia: above pH normal range  Acidosis: addition of excess acid / removal of base  Alkalosis: addition of excess base / loss of acid Acid-Base Disturbances on Animal Health Chemical Buffer Systems Regulation of Acid-Base Balance: Three systems maintain or regulate acid-base homeostasis: (1) intracellular & extracellular buffers (2) the lungs (3) the kidneys Role of Respiratory System Regulation of Acid-Base Balance Role of Renal System  HENDERSON HASSELBALCH EQUATION  pH: This is the measure of the acidity or alkalinity of a solution.  pKa: The negative logarithm of the acid dissociation constant (Ka).  [Base]: Concentration of the conjugate base (the species that has lost a proton).  [Acid]: Concentration of the weak acid (the species that can donate a proton). Equal Base and Acid: pH=pKa Application in Acid-Base Balance 1. Buffer System Analysis  2. Body Fluid pH Determination  Visual tool to assess and determine the type of 3. Diagnosis of Acid-Base Disorders acidosis or alkalosis. 4. Understanding Respiratory and Metabolic Influences  Plots pH and [HCO₃⁻] values.  Considers hemoglobin as a buffer.  Useful for approximating the severity of acid-base Laboratory Parameters Used to Assess Acid-Base Status disturbances.  Base Excess Estimation 2. Siggaard-Andersen Alignment Nomogram  Used to determine base excess, a measure of metabolic component in acid-base balance.  Less useful for visualizing the type of acid-base disturbance compared to the pH-bicarbonate diagram.  Often integrated into blood gas analyzers which adjust for hemoglobin concentration and return values for pH, PCO₂, [HCO₃⁻], and base excess. pH-Bicarbonate Diagram pCO₂ Isobar:  Points along this line represent combinations of bicarbonate and pH at a fixed Pco₂. o Right: Indicates respiratory alkalosis (decreased Pco₂). o Left: Indicates respiratory acidosis (increased Pco₂). Tests Used to Measure the Laboratory Parameters of Acid Normal Buffer Line: Base Status  Points on this line reflect balanced metabolic acids and Two Types of Clinical Evaluation Systems: bases. o Above: Indicates metabolic alkalosis. 1. pH-Bicarbonate Diagram o Below: Indicates metabolic acidosis. Compensatory Mechanisms: Four Primary Acid-Base Disorders  Renal Compensation: Adjusts bicarbonate levels to counteract respiratory alkalosis or acidosis.  Respiratory Compensation: Adjusts CO₂ levels to counteract metabolic alkalosis or acidosis Anion Gap and Acid-Base Status:  The anion gap method is an alternative, less precise method used when a pH blood gas analyzer is not available.  Plasma cations (mainly sodium and potassium) are balanced by anions (mainly chloride and bicarbonate) to maintain electrical neutrality.  There is an apparent anion gap due to unmeasured ions (e.g., sulfates, phosphates, proteins). Metabolic Acidosis  Ketosis: Ketone acids lower bicarbonate levels, leading to an increased anion gap.  Decreased plasma HC03 or Serum TCO2 concentrations indicate metabolic acidosis. Anion Gap Changes: Moderate Metabolic Acidosis:  Increased Anion Gap: Often indicates metabolic acidosis due to retention of unmeasured acids (e.g.,  15-20 mmol/L in most species ketoacidosis).  12-17 mmol/L in dogs and cats  Decreased Anion Gap: Associated with conditions like Severe Metabolic Acidosis: hypoproteinemic alkalosis or increases in unmeasured cations (e.g., hypercalcemia).  32 mmol/L in dogs and cats Possible Causes: Clinical Signs: i. Hypoventilation: Slow, shallow breathing ii. Muscle Cramps or Twitching iii. Paresthesia iv. Tetany v. Generalized muscle weakness. vi. Lightheadedness or feeling faint. vii. Altered mental status or difficulty concentrating. viii. Nausea and Vomiting Respiratory Acidosis  Occurs when there is an accumulation of CO2 in the body due to hypoventilation. a) Decrease in blood pH (acidemia) b) Increased PaCO2 (hypercapnia): ❖ >45mm Hg in most species c) Normal to slightly elevated HCO3 levels d) Elevated Potassium levels (Hyperkalemia) Possible Causes:  Possible Causes: Clinical Signs: i. Hypoventilation ❖ Dyspnea: Rapid, Shallow Breathing: Ineffective Clinical Signs: breathing pattern. ii. Altered mental status or disorientation. i. Hyperventilation iii. Headache: ii. Lightheadedness iv. Drowsiness or Fatigue iii. Paresthesia v. Cyanosis iv. Chest Pain vi. Shaking or muscle twitching v. Palpitations: Feeling of rapid or irregular heartbeats. vi. Difficulty thinking clearly or disorientation. vii. Muscle Cramps or Twitching: Involuntary muscle Respiratory Alkalosis spasms.  Occurs when there is a decrease of CO2 in the body due to hyperventilation. Compensations ❖ Increase in blood pH (alkalemia) 1. Modulation by Organic Acids ❖ Decreased PaCO2 (hypocapnia):