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.