Clinical Chemistry 2 Midterms 2024-2025 PDF

CLINICAL CHEMISTRY 2 CLICHM2/ LCM / MWF10:00–11:00AM 3RD YEAR - 1ST SEMESTER M...

CLINICAL CHEMISTRY 2 CLICHM2/ LCM / MWF10:00–11:00AM 3RD YEAR - 1ST SEMESTER M 2024-2025 L S CHAPTER I ELECTROLYTES WATER (H2O) They are classified as either anions or cations based on the type of Average water content of the human body varies from 40% to 75% of charge they carry. total body weight. Charged ions found in intracellular and extracellular fluids. Values declining with age and especially with obesity. Main source Electrolytes with a positive charge that move o Water Intake toward the cathode. o Food intake CATIONS o Fat metabolism Examples: Sodium, Potassium, Calcium and Magnesium. Women have lower average water content than do men. Electrolytes with a negative charge that move o Men have a higher fat content. toward the anode. Universal Solvent ANIONS Examples: Chloride, Bicarbonate FUNCTIONS phosphate, Sulfate, Organic acid and 1. It transports nutrients to the different cells. proteins 2. It determines cell volume by its transport into and out of the FUNCTIONS cells. Volume and Osmotic Regulation 3. Removes waste products. The one that maintains this is the RAAS. o Eliminate through urination. When there is a decrease in blood volume 4. Acts a body’s coolant. or blood pressure, o Act as coolant through sweating. o these cells release an enzyme LOCATION called renin into the INTRACELLULAR FLUID EXTRACELLULAR FLUID bloodstream. 2/3 TBW 1/3 TBW o Renin converts Fluid inside the cells. angiotensinogen into Salt is the main determinant of Inside the Packed Red angiotensin I into angiotensin ECF. II, which is the active form. Blood Cell. Main electrolytes: Main electrolytes: Vasoconstriction o Angiotensin II causes blood Potassium Sodium vessels to constrict (narrow), Magnesium Fluoride increasing blood pressure. Phosphate Bicarbonate (Salt) Na+ Cl- K+ o Angiotensin II also stimulates EXTRACELLULAR FLUID the adrenal glands to release INTRAVASCULAR INTERSTITIAL TRANSCELLULAR aldosterone to regulate volume. ECF FLUID FLUID ALDOSTERONE’S ROLE Surrounds the Sodium and Water Retention Plasma cells in the tissue. Epithelial-lined cells o Aldosterone acts on the kidneys, Found between Found on CSF, specifically on the distal tubules Inside the vasculature the RBC and Synovial, Pericardial, and collecting ducts, or in blood vessel. Blood vessels. Pleural. o To increase the reabsorption of sodium and excretion of Take note: potassium. Normal plasma is about 93% water, with the remaining volume As sodium is reabsorbed, water follows occupied by lipids and proteins (7%). (osmosis), increasing blood volume. TRANSPORT This sodium retention helps to maintain ACTIVE DIFFUSION/PASSIVE osmotic pressure, which is the balance of solutes and water inside the blood. The passive movement of ions (no energy Myocardial rhythm and Contractility consumed) across a membrane. K+ Mg2+ Ca2+ Important to have a proper contraction and nerve Depends on: impulse. A mechanism that o Size and charge of the ion 2+ 2+ - requires energy to being transported. Ca Mg Cl Cofactors in Enzyme Activation move ions across o Nature of the membrane Zn2+ Hastens biochemical reactions. cellular membranes. (permeability) through Regulation of Adenosine Triphosphatase Ion which it is passing. Mg2+ Pumps May be altered by physiologic For precise control of homeostasis inside the cell. and hormonal processes. Maintenance of Acid–Base balance HCO3- Cl- K+ Normal pH: 7.35 - 7.45 (Normal is 7.4) OSMOLALITY Ca2+ Mg2+ Blood Coagulation A physical property of a solution that is based on the concentration of Neuromuscular Excitability solutes (expressed as millimoles) per kilogram of solvent (w/w). Refers to the ability of the nerve and muscles to Reflects the number of dissolved particles and these particles Ca2+ Mg2+ K+ propagate electric signals. will affect the osmotic pressure. To have proper muscle contraction/movement. ↑ Osmolality → ↑ Solutes = Dehydrated Production and use of ATP from Glucose So, if dehydrated, the compensatory mechanism would be to Mg2+ PO43- Cofactors in the production of energy. hydrate which is to decrease the osmolality. LILI NOTES 1  ELECTROLYTES / MIDTERMS Hydrate with the help of a hormone called Arginine OSMOLAL GAP Vasopressin Hormone (AVP) and formerly known as The difference between the measured osmolality and the calculated Antidiuretic Hormone. osmolality. Instead of urinating the water in your body, it reabsorbs back It indirectly indicates the presence of osmotically active the water in the circulation, hydrate, and decrease osmolality. substances other than sodium, urea, and glucose but not only these. Reabsorption of H2O → ↑ Hydration = ↓ Osmolality It also measures the amount of ethanol, methanol, ethylene Secretion is stimulated by the hypothalamus in response to an glycol, and lactate or even β-Hydroxybutyrate. increased osmolality of blood. Used as a diagnostic tool for the determination of Toxic Alcohol Ingestion. IMPORTANCE OF REGULATION OF BLOOD VOLUME o Also evaluate Renal Function. Adequate blood volume is essential to maintain blood pressure and o Also useful in differentiating causes of metabolic ensure good perfusion to all tissues and organs. acidosis. FACTORS AFFECTING BLOOD VOLUME FORMULAS Renin-Angiotensin- Responds primarily to a decreased blood Glucose (mg/dL) BUN (mg/dL) Aldosterone 2 Na + + volume. 20 3 Hormone System ↓ BV → ↑ RAAS = ↓ BP (RAAS) 1.86 Glucose (mg/dL) BUN (mg/dL) Released from the myocardial atria in Na + 18 + 2.8 + 9 response to volume expansion, Atrial Natriuretic Promotes Na+ excretion in the REFERENCE RANGE FOR OSMOLALITY Peptide (ANP) kidney. Serum 275-295 mOsm/kg Regulates blood pressure and Urine (24h) 300-900 mOsm/kg blood volume. Urine/Serum Ratio 1.03-3.0 Volume Receptors Random Urine 50-1200 mOsm/kg Independent of Osmolal Gap 5-10 mOsm/kg Osmolality Conserves water by renal reabsorption. stimulate the release of AVP SODIUM (Na+) It represents the amount of fluid that is Sodium is the most abundant cation in the ECF, representing 90% of Glomerular being filtered by the Bowman’s capsule of all extracellular cations. filtration Rate the kidney. (GFR) Increases with volume expansion. It largely determines the osmolality of the plasma. Decreases with volume depletion. Also known as “Natrium” All Other Things Increased plasma Na+ will increase urinary It is the major contributor of osmolality. Equal Na+. It is the principle osmotic particle outside the cell. Take note: Major electrolyte that contributes to the proper regulation of blood Urine osmolality values may vary widely depending on water volume and blood pressure. intake and the circumstances of collection. Concentration of plasma Na+ depends greatly on the intake Generally decreased in diabetes insipidus and polydipsia and excretion of water. (excessive H2O intake). Increased in the syndrome of inappropriate antidiuretic REGULATION OF PLASMA SODIUM hormone (SIADH) secretion and hypovolemia. Intake of Stimulated or suppressed by plasma osmolality. Water in ↑ Particles in ↑ Osmo = = Dehydration DETERMINATION OF OSMOLALITY circulation response to Intake of SPECIMEN = ↑ Plasma Osmo = Hydration THIRST H 2O Can be measured using SERUM or URINE. Largely affected by AVP release in response to Plasma cannot be used because it utilizes anticoagulant which changes in either blood volume or osmolality. contains some osmotically active substances particles that Decrease water intake results to increase can increase osmolality. plasma osmolality. Major electrolyte concentrations, mainly Sodium, Chloride, Excretion AVP minimizes renal water loss. and Bicarbonate. o AVP inhibits or decrease o Provide the largest contribution to the osmolality of Water urination. value of serum. o Instead of excretion of water, AVP Take note: stimulates reabsorption in Turbid serum and urine samples should be centrifuged before circulation resulting to inhibition analysis to remove any extraneous particles. of urine and excretion. Samples must be free of particulate matter to obtain Blood Affects Na+ excretion through aldosterone, accurate results. Volume angiotensin II, and ANP. If reusable sample cups are used, Status Help kidneys reabsorb Na+ in circulation. o They should be thoroughly cleaned, disinfected, Take note: and dried between each use to prevent The kidneys have the ability to conserve or excrete large amounts contamination. of Na+, depending on the Na+ content of the ECF and the blood volume. HORMONES AFFECTING SODIUM LEVELS LILI NOTES 2  ELECTROLYTES / MIDTERMS Sodium retention by increasing its reabsorption Secondary: Renin deficiency in the Proximal Convoluted Tubules and Loop o Without adequate secretion, of Henle which increases potassium excretion. there is no aldosterone Aldosterone Mainly, it will increase sodium by production. reabsorption. o This will result to sodium is Potassium is decreased in blood due to not adequately reabsorbed excretion. back in the circulation. Blocks aldosterone and renin secretion. Addison’s disease Inhibits the action of angiotensin II and o Urinary excretion of sodium. vasopressin resulting to Gastrointestinal NATRIURESIS. Diarrhea Atrial o If there is no AVP is present, NON-RENAL Vomiting Natriuretic Na+ is excreted in the urine. LOSSES Skin Peptide (ANP Opposite to the effect of aldosterone. Burns, trauma As ANP is released, aldosterone is Excessive sweating inhibited, resulting to decreased sodium DILUTIONAL HYPONATREMIA reabsorption and increases potassium in circulation. Loss due to an increase in water volume. Syndrome of ↓ K+ in Causes an increase in water retention because of ↑ Aldosterone = ↑ Na+ Reabsorption = Inappropriate circulation increased AVP (ADH) production. Anti Diuretic ↑ K+ in Cause an uncontrolled water retention. ↑ ANP = ↓ Na+ Reabsorption = Hormone circulation Sodium content in circulation will be (SIADH) diluted. IMPORTANT VALUES Secretion Renal threshold is the concentration of a substance that is dissolved in Congestive heart failure the blood above which the kidneys begin to remove it in the urine. Cirrhosis & Nephrotic syndrome Example: the limit of the kidneys to retain is 110-130 mmol/L. Decrease in plasma proteins results in Generalized The excess needs to be removed. Edema decrease colloidal osmotic pressure. Kidneys are the ultimate regulators of the amount of sodium o This will result to migration of or potassium. water to the tissues, causing edema. Renal Threshold of Na+ 110-130 mmol/L Increased blood glucose level. NORMAL VALUES OF Na+ Glucose is considered a solute. 136-145 mmol/L Solutes will cause shift of water from the Serum/Plasma 135-145 mmol/L or mEq/L Hyperglycemia cells to the blood. (books) Water that comes out from the cell 40-220 mmol/L dilutes the sodium concentration in the Urine (24h) blood. Varies with diet. CSF 136-150 mmol/L ARTIFACTUAL/PSEUDOHYPONATREMIA DIAGNOSTIC SIGNIFICANCE Caused by an analytical error. HYPONATREMIA Sodium that is measured using the method Ion One of the most common electrolyte disorders and can be assessed Selective Electrodes (ISE) in patients with either by the cause of the decrease or with the osmolality level. hyperlipidemia and hyperproteinemia due to Reflection of the ratio of sodium to volume in the plasma. plasma dilution. This does not reflect directly about the total body sodium Most common cause of error: Build-up content. of proteins in the membrane used in o Thus, it can occur to low or normal. ISE. Serum/Plasma levels