Major Electrolytes
Isotonic solution
equal osmolality inside and outside the cell. no net water movement, cell size remains the same
Causes of Hypernatremia
excess loss of water relative to sodium loss, decreased water intake and increased sodium intake or retention. elevated levels of Na in blood.
Causes of Hyperkalemia
hemolyzed specimen, acidosis.
Hypertonic solution
higher osmolality outside than inside the cell. water moves out of cell in an attempt to equalize the solute concentration cell shrinks.
Increased sodium concentrations
in diarrhea, short term vomiting, severe polyuria
Electrolytes
ions carrying electrical charge. Classified as cations or anions. Located throughout body in tissues, fluids and bones.
3 Stages of Magnesium:
Ionized (free 60%) protein bond (40%) complexed to citrate, phosphate, and other anions. Ionized magnesium is the physiologically active form of magnesium.
Phosphate
Major Intracellular anion. regulated by parathyroid hormone (PTH)
Causes of Hypokalemia
Malabsorption, alkalosis.
Hypomagnesaemia
Malabsorption, kidney reabsorption problems, hypoparathyroidism
Anions
Negatively charged. Gains one or more electrons. Major: Cl, HCO3, PO4 ^3-, SO4 ^2-, organic acids, proteins.
Bicarbonate: specimen collection
Plasma anticoagulant (heparinized). serum specimens should be anaerobic for the highest accuracy. sample must remain capped.
Cations
Positively charged. Losses one or more electrons. Major: Na, K, Ca, Mg.
Intracellular ions
Potassium, Phosphate, Magnesium
Increased sodium loss
certain diurectics, prolonged vomiting or diarrhea or severe burns.
Anion Gap
concentration of undetermined anions present in the blood, calculated as the difference between the measured total cations and measured total anions. (needs to be positive whole number). Useful in detectubg aktered concentrations of anions other than Cl^- and HCO3^- Reference Range: 8-16 mmol/L
Causes of Hyponatremia
deficiency of sodium in blood. low sodium levels are found in severe polyuria, diarrhea, and some renal tubular diseases. decreased level of Na in blood.
Causes of Hyperchloremia
dehydration, excessive saline, hyperaldosteronism.
Causes of Hypochloremia
severe vomiting, diarrhea, nasogastric suction.
Calculating Anion Gap
2 Ways: 1. (Na+) - (CL^-+HCO3^-) 2. (Na^+ + K^+) - (Cl^- + HCO3^-)
Magnesium
2nd most abundant cation in intracellular fluid.
Bicarbonate
2nd most abundant extracellular anion. maintains ionic charge neutrality.
Hypocalcemia
AMI, Hypoparathyroidism, malabsorption, Vitamin D deficiency
Hypermagnesaemia
Antacids, renal failure, hyperparathyroidism.
ADH
Anti-Diuretic is a hormone secreted by posterior pituitary gland in response to increased plasma osmolality.
Types of CO2
CO2+H2O=H2CO3=H +HCO3^- bicarbonate- (HCO3^-) represents 90% of TCO2 in plasma. CO2 bound lossely to plasma proteins. Physically dissolved, free CO2. Undissociated Carbonic Acid (H2CO3)
Bicarbonate: Metabolic Acidosis
Caused by increased renal excretion of HCO3^- Decreased PCO2 (partial pressure CO2) due to compensation by hyperventilation.
Osmolarity
Concentration od osmotically active particles in solution reported in milliosmoles per liter, not routinely used.
Osmolality
Concentration of osmotically active particles in solution expressed in terms of osmoles od solute per kilogram of solvent.
Increased Anion Gap
Decreased unmeasured cations from Hypokalemia, Hypocalcemia and Hypomagnesium. Increased unmeasured Anions. LAB ERROR. Accumulation of inorganic acids. Ingestions of toxic substances.
Bicarbonate: Metabolic Alkalosis
Excessive alkali intake (antacids)
Calcium
Found in bones and teeth. most abundant electrolyte in the body. Homeostasis regulated by parathyroid hormone (PTH).
Hypercalcemia
Hyperparathyroidism, excessive vitamin D, parathyroid tumors
Hypophosphatemia
Hyperparathyroidism. alcoholism
Causes of Hyperphosphatemia
Hypoparathyroidism. Chemotherapy, any major surgery with massive bone destruction (broken bone releasing phosphate).
Decreased Anion Gap
Increased unmeasured cations- Hypercalcemia, Hyperkalemia, Hypermagnesium. Decreased unmeasured anion. Hypoalbuminemia, dilution of extracellular fluid.
Phosphate Functions
Promotes energy transfer by forming ATP. essential for bone and teeth (follows calcium). buffers acids and bases.
3 Forms of Calcium
Protein-bound ionized (only physiologically active) complexed (as undissociated salts)
Extracellular ions
Sodium, Chloride, and Bicarbonate
Methods of Electrolyte Measurement
Spectrp[hotometric- Total Ca, Total Mg, Phosphate (Piccolo-Ca2+, Phosphate).
Clinical Significance of Bicarbonate
acid-base imbalances are influenced by changes in HCO3^- and CO2 levels.
Hypotonic solution
lower osmolality outside the cell than inside the cell. water moves into cell in an attempt to equalize the solute concentrations cell swells, with the potential to rupture
Sodium (Na)
major extracellular cation. determines osmolality of plasma. regulates BP, reabsorb water. Regulated by Kidneys.
Chloride
major extracellular fluid anion. major anion counterbalances Sodium a cation. absored by small intestines.
Potassium (K)
major intracellular cation. Regulates neuromuscular excitability, conractions of the heart. helps maintains electrical neutrality.
TCO2
measurement of TCO2 is chiefly done to evaluate HCO3^- levels. bicarbonate and dissolved CO2 are directly involved in te body's acid-base balance.
Osmotic pressure
pressure required to stop osmosis through semi-permeable membrane between solutions of different solute concentrations.