Electrolytes

• positively charged ions; cathode (-) electrode


  Cations
• negatively charged ions; anode (+) electrode


  Anions
• • Sodium (Na+)
  • Potassium (K+)
  • Chloride (Cl-)
  • Bicarbonate (HCO3+)


  Four Major Electrolytes
• Cation:

  • Sodium (major)

  Anion:

  • Chloride (major counter ion of Na+)
  • Second: Bicarbonate (HCO3-)

  Extracellular
• Cation:

  • Potassium (major countercurrent ion of Na+)
  • Second: Magnesium (Mg+)

  Anion:

  • Organic Phosphate (PO4-)


  Intracellular
• inorganic homogeneous solid substances

  Minerals
• 1. Macrominerals (major elements): present in body in quantities >5 grams, with a daily dietary requirement of >/= 100 mg
  2. Microminerals (trace elements): <0.01% of dry body weight - trace elements - mg/L; Ultra-trace elements - ug/L


  Classification of Minerals
• • organic substance essential in minute quantities to nutrition, acting as coenzymes in regulation of metabolic processes
  • some are produced by body, others are present in food


  Vitamins
• • 60-70% = average water content of the body
  • solvent of all human body metabolism
  • nutrient transport
  • removal of waste product
  • determination of cell volume
  • body's coolant
  • sweat sodium-potassium ratio - 1:10


  Water
• • Intracellular Fluid (ICF) - fluid inside cells and is 2/3 of total body water
  • Extracellular Fluid (ECF) - is 1/3 of tbw


  Distribution of Water
• • Intravascular fluid - fluid in blood vessels; normal plasma have 93% water + 7% solutes
  • Interstitial cell fluid - fluid that surrounds the cells in the tissue; outside the blood vessels


  ECF components
• • is maintained by electrolytes as they exert osmotic pressure which tends to hold water
  • moves through water medium: a. Diffusion - passive movement of ions across a membrane b. Active transport - mechanism that requires energy to move ions across cellular membranes


  Regulation of Water
• physical property of a solution that is based on the concentration of solutes (millimoles) per kilogram of solvent (w/w)


  Osmolality of water
• 275-295 mOsm/kg


  Serum osmolality
• 300-900 mOsm/kg


  Urine (24h) osmolality
• 5-10 mOsm/kg


  Osmolal gap
• • aka Natrium
  • major extracellular cation and major contributor of osmolality (sodium, chloride, bicarbonate)
  • dependent on hydration


  Sodium
• • Plasma osmolality
  • Water excretion (sodium problem)
  • Blood volume (water problem)


  Functions of Sodium
• 1. Aldosterone: promotes absorption of Na+ in distal tube
  2. Atrial Natriuretic Factor/ Peptide (ANF/ANP): blocks aldosterone and renin secretion, inhibits the action of angiotensin II and vasopressin


  Regulation of Sodium
• 135-145 mmol/L


  Serum/ Plasma RR of sodium
• 40-220 mmol/d


  Urine (24h) RR of sodium
• 135-150 mmol/L


  CSF RR of sodium
• All confirmed serum sodium abnormalities must be followed up with urinalysis (urine Na+ & urine osmolality) on the patient, who should be fluid restricted.
• • Excess water loss
  • Decreased water intake
  • Increased intake or retention 


  Causes of Hypernatremia
• • Increased sodium loss
  • Increased water retention (hypervolemic)
  • Water imbalance


  Causes of Hyponatremia (<135 mmol/L)
• • Diabetes insipidus
  • Renal tubular disorder
  • Profuse sweating
  • Severe burns
  • Vomiting
  • Fever
  • Hyperventilation

  Excess water loss
• • Older persons
  • Infants
  • Mental impairment


  Decreased water intake
• • Hyperaldosteronism (Conn's disease)
  • Sodium bicarbonate infusion
  • Increased oral or IV intake of NaCl
  • Dialysis fluid excess
  • Ingestion of sea water

  Increased intake or retention
• • Conditions: Ketonuria, prolonged vomiting/diarrhea, severe burns, salt-losing nephropathy
  • Deficiencies: Potassium, Aldosterone
  • Disorder: Hypoadrenalism (Addison's disease)
  • Exogeneous: Diuretic use (thiazides)


  Increased sodium loss
• • Impaired filtration (urine Na+ >/= 20mmol/d): Renal failure
  • Decreased colloid osmotic pressure (urine Na+ < 20mmol/d): Nephrotic syndrome, hepatic cirrhosis, CHF


  Increased water retention (hypervolemic)
• • Excess water intake (primary polydipsia)
  • Syndrome of Inappropriate AVP (ADH) Secretion (SIADH)
  • Pseudohyponatremia
  • CNS abnormalities
  • Pulmonary disease
  • Myxedema marked hemolysis


  Water imbalance
• • CNS involvement, altered mental status, lethargy, irritability, restlessness, seizure
  • Muscle twitching, hyper reflexes
  • Fever, nausea, vomiting, difficult respiration, increased thirst
  • >160 mmol/L: death(60-75% mortality rate)


  Symptoms of Hypernatremia
• • 125-130 mmol/L: GI symptoms
  • <125 mmol/L: severe neuropsychiatric symptoms, nausea, vomiting, muscular weakness, headache, lethargy, ataxia, seizures, coma, respiratory depression
  • <120 mmol/L: for 48 hours or less (acute) considered a medical emergency 


  Symptoms of Hyponatremia
• • directed at correction of water depletion or sodium retention
  • Consideration: speed of correction
  • Too rapid = cerebral edema


  Treatment of Hypernatremia
• • directed at correction of water retention or sodium loss in excess of water loss
  • Consideration: onset (acute/chronic), severity, speed of correction
  • Too rapid = cerebral myelinolysis
  • Too slow = cerebral edema
  • fluid restriction
  • hypertonic saline
  • Conivaplan 


  Treatment of Hyponatremia
• 1. With Low Osmolality
  2. With Normal Osmolality
  3. With High Osmolality


  Categories of Hyponatremia
• • increased sodium loss
  • increased water retention


  With Low Osmolality
• • Increased non sodium cations
  • lithium excess
  • increased gamma globulins - cationic (MM)
  • severe hyperkalemia
  • severe hypermagnesemia
  • severe hypercalcemia
  • pseudohyponatremia
  • hyperlipidemia/hyperproteinemia
  • Pseudohyperkalemia (in vitro hemolysis)


  With Normal Osmolality
• • Hyperglycemia
  • Mannitol infusion


  With High Osmolality
• • aka Kalium
  • major intracellular cation (concentration 20x greater inside cells than outside)
  • single most important analyte in terms of abnormality being life threatening
  • filtered at glomeruli and mostly (70-80%) reabsorbed by active and passive mechanism in proximal tube
  • in ascending limb of Henle's loop, reabsorbed with sodium and chloride by the sodium potassium chloride cotransporter


  Potassium