Fluid and Electrolyte Balance Quiz

Alterations in Fluid and Electrolytes

• Fluid compartments and sub-compartments of the body and relative fluid amounts are identified.
• Mechanisms of fluid movement between compartments are described.
• Routes of water intake and output are identified.
• The thirst mechanism and its cessation are explained.
• Compensation methods for water shifts in the body are indicated.
• Antidiuretic hormone (ADH) activity is discussed.
• Imbalances of fluid homeostasis and their consequences are described.
• Mechanisms regulating sodium, potassium, calcium, phosphate, and other anions in body fluids are explained.
• Pathophysiology of diabetes insipidus is explored.
• Pathophysiology of the syndrome of inappropriate ADH (SIADH) is detailed.

Fluids, Ions, Nonelectrolytes, and Electrolytes

• Body fluids, Ions, Nonelectrolytes, and Electrolytes are categorized.
• Components of body fluids, such as cerebrospinal fluid, intraocular fluid, digestive juices, serous fluid and synovial fluid in joints are listed.

Functions of Body Fluids

• Body fluids transport gases, nutrients, and wastes.
• They generate electrical activity for body functions.
• They are involved in food transformation to energy.
• They maintain overall body function.

Distribution of Body Fluids

• Intracellular fluid (ICF) contains fluid inside cells, majority of body water.
• Extracellular fluid (ECF) contains fluids outside cells, including interstitial fluid and plasma.
• ICF has a high concentration of potassium (K+).
• ECF has a high concentration of sodium (Na+).

Composition of the ECF, Plasma, and Interstitial Fluids

• ECF components include large amounts of sodium (Na+) and chloride (Cl-), moderate bicarbonate (HCO3-), and small quantities of potassium (K+), magnesium (Mg2+), calcium (Ca2+), and phosphate (PO43-).

Composition of the ICF

• ICF mostly lacks calcium (Ca2+).
• It has small amounts of sodium (Na+), chloride (Cl-), bicarbonate (HCO3-), and phosphate (PO43-).
• It has moderate amounts of magnesium (Mg2+).
• It has large amounts of potassium (K+).
• ICF is located between capillaries and cells and separates cells from surroundings by hydrostatic and osmotic pressures.

Diffusion and Osmosis

• Diffusion is movement of particles along a concentration gradient (high to low).
• Oxygen (O2) diffuses High to low and carbon dioxide (CO2) diffuses low to high.
• Osmosis is the movement of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration.

Tonicity

• Tonicity describes the effect of a solution's osmotic pressure on cell size.
• Isotonic solutions have the same concentration as the cell, maintaining cell size.
• Hypotonic solutions have a lower concentration than the cell, causing cell swelling.
• Hypertonic solutions have a higher concentration than the cell, causing cell shrinkage.

Mechanisms Protecting Extracellular Fluid Volume

• Alterations in hemodynamic variables such as vasoconstriction and increased heart rate impact fluid volume maintenance.
• Isotonic contraction or expansion of extracellular fluid (ECF) volume, related to concentration, is discussed.
• Hypotonic dilution or hypertonic concentration of extracellular sodium alters ECF volume and blood circulation.
• The body compensates for fluid loss by altering hemodynamics and constricting blood vessels.

Edema

• Edema is the accumulation of fluid in the extracellular space.
• Pitting edema shows a pit after pressure is released, while non-pitting edema does not retain this indentation.
• Edema formation results from increased capillary filtration pressure, decreased capillary colloidal osmotic pressure, and increased capillary permeability.
• Causes, including increased capillary filtration pressure, reduced capillary colloidal osmotic pressure, and increased capillary permeability are detailed along with lymphatic flow disturbances.

Methods for Assessing Edema

• Daily weight, visual assessment, measurement of the affected part, and application of finger pressure are used for assessing edema.
• Pitting edema is quantified in mm.

Physiologic Mechanisms Assisting in Regulating Body Water

• The thirst mechanism is primarily involved in regulating water intake.
• Older adults may have impaired thirst mechanisms and be more vulnerable to dehydration.
• ADH (antidiuretic hormone) regulates water output by increasing water reabsorption.

Water and Nat Balance

• Baroreceptors monitor blood vessel pressure and send signals to regulate the volume of extra cellular fluid (ECF).
• The Renin-Angiotensin-Aldosterone System (RAAS) regulates sodium and water excretion by the kidneys.
• Atrial Natriuretic Peptide (ANP) also plays a role by influencing sodium excretion.

Regulators of Sodium

• The kidneys are the main regulators of sodium, monitoring arterial pressure.
• The rate of sodium regulation is coordinated by the sympathetic nervous system and the renin-angiotensin-aldosterone system (RAAS).
• Atrial natriuretic peptide (ANP) may additionally regulate sodium excretion.

Assessment of Body Fluid Loss

• Assessment of body fluid loss involves evaluating factors such as heart rate, blood pressure, postural hypotension, venous volume/filling, capillary refill rate, and urine output.
• Oliguria and anuria represent insufficient urine output.

Causes of Fluid Volume Deficit

• Abnormal losses through the gastrointestinal (GI) tract or kidneys are presented as major causes of fluid volume deficit.
• Insensible fluid losses through perspiration and respiratory water vapor are additional causes.
• Excessive fluid loss can also occur due to bleeding or movement of fluid into third spaces.
• Inadequate fluid intake, and increased metabolic rate contribute to fluid volume deficit.

Extracellular Fluid Volume Excess

• Isotonic expansion of the ECF compartment includes increases in interstitial and vascular volumes.
• Increased total body sodium that is proportionally accompanied by increased body water leads to sodium and water elimination problems.
• Renal function issues, heart failure, liver failure, and corticosteroid excess impede sodium and water elimination.

Causes of Fluid Volume Excess

• Inadequate sodium and water elimination (impaired kidney function or heart failure), excessive sodium intake relative to output, and excessive fluid intake relative to output contribute to fluid volume excess.

ADH: Antidiuretic Hormone

• ADH (also known as vasopressin) retains water decreasing urination.
• ADH is produced in the hypothalamus and stored in the posterior pituitary.
• ADH is released when needed into the blood stream to cause the kidneys to concentrate urine by returning excess water to the blood stream.

SIADH versus Diabetes Insipidus

• Differences between SIADH and diabetes insipidus are indicated.

Diabetes Insipidus (ADH deficiency)

• Diabetes insipidus is a clinical syndrome characterized by excessive urination and thirst with gradual or sudden onset.
• Causes include central/idiopathic DI, head injuries, neurosurgical procedures, genetic disorders, idiopathic, and pituitary tumors.
• Symptoms are excessive urination.

Symptoms

• Clinical presentation depends on the cause, severity, and associated medical conditions.
• Excessive thirst may be intense or uncontrollable.
• Excessive urine output and urine colored like water are key symptoms.

Diagnosis: labs reflect dilution

• Serum sodium, urine specific gravity, urine osmolality, serum osmolality, urine sodium, and ADH levels are used in diagnosis.
• Values for these parameters in the context of dilution are detailed.

Treatment

• Treatment of the underlying cause is prioritized.
• Fluid administration (oral or intravenous) matching urine output is crucial.
• Medications such as DDAVP (Desmopressin) may be used for diabetes insipidus.

SIADH

• SIADH is a disorder of fluid and electrolyte balance due to excessive ADH secretion.
• Dilutional hyponatremia (water intoxication), a consequence of fluid and electrolyte imbalance, is stated along with causes, including fluid retention.
• Myoclonus, a quick involuntary muscle jerk response to low sodium, is presented, along with other causes to the brain and nervous system.

Most Common Cause

• Postoperative surgical stress induces water retention possibly lasting up to 5 days.
• Women might be more susceptible to water retention than men due to factors such as smaller intravascular volumes and hormonal variations.

Diagnosis

• Elevated ADH despite normal serum osmolality, decreased serum sodium, decreased serum osmolality, increased urine osmolality, increased urine sodium, and elevated urine specific gravity indicate possible SIADH.

Signs & Symptoms

• Weight gain is a common symptom of SIADH.
• Clinically significant edema.
• Nausea/vomiting
• Muscle cramps
• Confusion
• Restlessness
• Irritability

Symptoms

• Chronic hyponatremia lasts longer than 48 hours.
• Symptoms such as anorexia, nausea/vomiting, and restlessness may be present.

Treatment

• Slowing the rate of sodium correction to prevent cerebral demyelination syndrome is critical.
• Fluid restriction (800–1000 mL/day) may be medically employed or in certain cases the body will recover naturally.

Complications of Treatment

• Central pontine myelinolysis, spastic quadriparesis, pseudobulbar palsy, spastic paralysis of the larynx and pharynx, and airway occlusion are possible complications.
• Rate of sodium correction has a link to the duration of hyponatremia.

Treatment Complications

• Alcoholics, malnourished individuals, elderly women on thiazides, and hypokalemic patients are at a higher risk.

Potassium Distribution and Regulation

• Potassium is highly concentrated inside cells.
• Normal serum potassium levels range from 3.5 to 5.0 mEq/L.
• Potassium stores correlate with body size and muscle mass.
• Potassium in plasma is regulated through both renal and transcellular mechanisms.

Abnormal Potassium

• Hypokalemia is a decrease in plasma potassium below 3.5 mEq/L, often due to inadequate intake or excessive losses.
• Hyperkalemia is an increase in plasma potassium above 5.0 mEq/L, generally due to decreased renal elimination or rapid administration.

Hyperkalemia

• Body "CARED too much about K+."
• Cellular movement of K+ from intracellular to extracellular (burns, tissue damage, etc.) can lead to the condition, which is associated with adrenal insufficiency and renal failure, excessive K+ intake, and certain drugs.
• Symptoms include muscle weakness, decreased cardiac output, respiratory compromise, and changes in the ECG.

Hyperkalemia VS Hypokalemia

• Symptoms of potassium fluctuations include various neuromuscular and cardiac manifestations.

Diagnosis and Treatment of Potassium Disorders

• Diagnosis of potassium disorders involves history, physical examination, ECG findings, and assessment of plasma potassium levels.
• Treatment often aims to redistribute potassium, lower concentration, and/or increase elimination.
• Sodium bicarbonate and insulin may be used to influence potassium distribution.

Vitamin D, Calcitonin, and Parathyroid Hormone

• Calcium, phosphate, and magnesium are crucial divalent cations in the body.
• Vitamin D increases calcium and phosphate absorption from the intestine.
• Calcitonin regulates calcium levels by acting on kidneys and bone to remove calcium from the extracellular circulation.
• Activated vitamin D is essential for body usage, which comes from the kidney.

Mechanisms Regulating Calcium, Phosphate, and Magnesium Balance

• Calcium, phosphate, and magnesium are important divalent cations in the body.
• Calcium, phosphate, and magnesium are ingested in the diet, absorbed in the intestine, filtered in the kidneys' glomerulus, reabsorbed in renal tubules, and eliminated in the urine.

Calcium Gain and Loss

• Dietary dairy foods provide calcium.
• Parathyroid hormone (PTH) and vitamin D stimulate calcium reabsorption in the kidneys.
• Losses are related to dietary intakes, intestinal secretion, and/or other processes.

Causes and Symptoms of Hypocalcemia

• Causes of low calcium levels include impaired ability to mobilize store from bones, abnormal losses from kidneys, and increased protein binding or chelation.
• Symptoms include Chvostek's and Trousseau's signs due to increased neuromuscular excitability.

Hypocalcemia: Chvostek's Sign & Trousseau's Sign

• Chvostek's sign and Trousseau's sign, symptoms of low calcium, are described.

Causes and Symptoms of Hypercalcemia

• Causes of high calcium levels stem from increased intestinal absorption (vitamin D excess, calcium supplements), increased bone resorption (parathyroid hormone over-activity, malignancy, prolonged immobilization), and decreased elimination (thiazide, lithium, etc.)
• Symptoms involve neural excitability changes, smooth and cardiac muscle alterations, and kidney exposure to high calcium.

Role of Phosphate in the Body

• Phosphate plays a crucial role in bone formation and various metabolic processes, including ATP formation and enzyme activity related to carbohydrate, fat, and protein metabolism.
• It serves as an acid-base buffer in extracellular fluid and in renal excretion of hydrogen ions.
• It's needed for oxygen delivery by red blood cells.
• It is needed for blood cell function (white blood cells and platelets).

Common Causes of Hypophosphatemia and Hyperphosphatemia

• Hypophosphatemia is characterized by phosphate depletion due to intestinal absorption issues, trans-compartmental shifts, or increased renal losses.
• Hyperphosphatemia arises from kidney failure (inability to excrete excess), rapid redistribution of intracellular phosphate, or excessive phosphate intake.

Magnesium Balance

• Magnesium is essential for reactions requiring ATP and is regulated at the kidney level.
• Dietary magnesium is absorbed from the intestine and excreted by the kidneys.
• Normal magnesium serum levels are between 1.8 to 2.6 mEq/L.

Hypomagnesemia

• Hypomagnesemia involves low magnesium, characterized by various symptoms potentially linked to neuromuscular and nervous system.

Manifestations of Hypomagnesemia

• Laboratory values (serum magnesium), neuromuscular (personality change, movements, signs), cardiovascular dysrhythmias are documented.

Athetoid and Choreiform Movements

• These involuntary movements may present as a possible symptom of hypomagnesemia.

Nystagmus

• Nystagmus is involuntary eye movement.

Causes of Hypermagnesemia

• Excessive magnesium intake (IV administrations or antacid use) may be the cause for hypermagnesemia.
• Impaired kidney function (decreased excretion) is another potential cause.

Signs & Symptoms of Hypermagnesemia

• Symptoms include depressed respiration, apnea, depressed mental status, bradycardia, and loss of deep tendon reflexes.

Practice Question: Potassium

• A patient vomiting excessively may experience hypokalemia, which is a potassium deficiency, due to potassium loss through vomiting.

Practice Question: Chvostek's and Trousseau's Sign

• Facial nerve twitching (Chvostek's sign) and carpal spasm (Trousseau's sign) can indicate low calcium levels.

Test your knowledge on the regulation of sodium balance and fluid homeostasis in the body. This quiz covers topics such as the role of antidiuretic hormone (ADH), consequences of fluid volume deficits, and mechanisms behind conditions like diabetes insipidus and SIADH. Dive into the intricacies of body fluid compartments and their functions.