Electrolytes 107

Chemicals that regulate body water loss

Aldosterone

Angiotensin

Anti-diuretic hormone

Atrial natriuretic peptide

inhibits sodium reabsorption, promoting excretion of water and sodium in urine by increasing GFR and vasodilation

atrial natriuretic peptide

inhibits secretion of aldosterone and anti-diuretic hormone

atrial natriuretic peptide

promotes reabsorption of sodium and excretion of potassium; subsequently increasing blood volume and pressure as it takes water with it; vasoconstriction

aldosterone

promotes reabsorption of water

anti-diuretic hormone

extracellular cations

Na

Ca

extracellular anions

Cl

HCO3

intracellular cations

K

Mg

intracellular anions

HPO4

Principal cation in the ECF

Sodium ion

Responsible for maintaining normal hydration and osmotic pressure. • Accounts for half of the osmolarity of ECF.

Sodium ion

Necessary for the generation and conduction of action potentials

Sodium ion

causes of hyponatremia

decreased Na intake, increased Na loss through vomiting, diarrhea, aldosterone deficiency, or taking certain diuretics, excessive water intake

signs and symptoms of hyponatremia

muscular weakness, dizziness, headache, hypotension; tachycardia and shock; mental confusion, stupor, and coma

causes of hypernatremia

dehydration, excessive Na intake through diet or IV fluids;

signs and symptoms of hypernatremia

intense thirst, hypertension, agitation, edema, and convulsions

major anion in the ECF

chloride ion

preferred counterions in making salts of acidic APIs / APIs rendered acidic

chloride ion

Responsible for maintaining proper hydration, osmotic pressure and cation-anion balance in vascular and interstitial fluid compartments

chloride ion

When used as the ammonium salt, may be used as urinary acidifier

chloride ion

Most abundant mineral in the body

calcium ion

Roles of calcium ion

• Hardness of teeth and bones.

• Blood clotting.

• Neurotransmitter release.

• Maintenance of muscle tone.

• Excitability of nervous and muscle tissue.

Regulator of Plasma Calcium ions

Parathyroid hormone (PTH)

function of PTH

Low Ca2+ levels stimulates the release of PTH, which results to:

• Release of Ca2+ ions from bones tissue.

• Reabsorption of Ca2+ ions from glomerular filtrate.

• Increase Calcitriol production → Increase absorption of Ca2+ ions from food.

causes of hypocalcemia

increased Ca loss, decreased Ca intake, elevated phosphate levels, hypoparathyroidism

signs and symptoms of hypocalcemia

numbness and tingling of fingers; hyperactive reflexes, muscle cramps, tetany, and convulsions; bone fractures; spams of laryngeal muscles that can cause death by asphixiation

causes of hypercalcemia

hyperparathyroidism, excessive Vit D, some cancers, Paget’s disease

signs and symptoms of hypercalcemia

lethargy, weakness, anorexia, nausea, vomiting, polyuria, itching, bone pain, depression, confusion, paresthesia, stupor, coma

Second most prevalent anion in ECF.

bicarbonate ion

Major Intracellular Cation

potassium ion

roles of potassium ion

• Establishment of Resting Membrane Potential of Neurons and Muscles.

• Helps maintain intracellular fluid volume.

• Often exchanged for H+ , helps regulate pH of body fluids

higher aldosterone equals ??? K excretion

increased

causes of hypokalemia

vomiting or diarrhea, hyperaldesteronism, kidney disease, and therapy w some diuretics

signs and symptoms of hypokalemia

muscle fatigue, flaccid paralysis, mental confusion, increased urine, shallow respiration, changes in electrocardiogram including flattening of T wave

causes of hyperkalemia

renal failure, aldosterone deficiency, crushing injuries to body tissues, transfusion of hemolyzed blood

signs and symptoms of hyperkalemia

irritability, nausea, vomiting. diarrhea, muscle weakness, death by ventricular fibrillation

regulates PTH and calcitriol

phosphate ion

causes of hypophosphatemia

increased urinary loss, decreased intestinal absorption, or increased utilization

signs and symptoms of hypophosphatemia

confusion, seizures, coma, chest and muscle pain, numbness and tingling of fingers, decreased coordination, memory loss, and lethargy

Second most common intracellular cation.

magnesium ion

roles of magnesium ion

• Cofactor of many metabolic enzymes.

• Essential for normal neuromuscular activity.

• Secretion of PTH depends on Mg2+ .

pharmacologic applications of magnesium

Magnesium salt

• IV or IM - general anesthetic

• PO - saline laxative (poorly absorbed by body)

MgSO4 - CNS depressants in obstetrics, convulsant states, and symptoms of tetanus

causes of hypomagnesemia

alcoholism, malnutrition, diabetes mellitus, diuretic therapy

signs and symptoms of hypomagnesemia

weakness, irritability, tetany, delirium, convulsions, confusion, anorexia, nausea, vomiting, paresthesia, and cardia arrythmias

causes of hypermagnesemia

renal failure, aldosterone deficiency, and hypoparathyroidism

signs and symptoms of hypermagnesemia

hypotension, muscular weakness or paralysis, nausea, vomiting, and altered mental functioning

Normal body pH

7.35 - 7.45

Most abundant buffer in ICF and blood plasma.

Protein buffer system

bicarbonate-carbonic acid ratio at pH 7.4

20:1

relationship of CO2 concentration and blood pH

inverse

high CO2 = low pH (acidic)

low CO2 = high pH (basic)

effect of Acidosis

• Depression of CNS through depression of synaptic transmission.

• Below pH 7, severe CNS depression (disorientation, comatose, death)

Effect of alkalosis

• Overexcitability of the CNS and peripheral nerves

• Nervousness, muscle spasms, convulsion, death

metabolic acidosis is caused by ___ level in arterial blood

abnormally low HCO3

metabolic alkalosis is caused by ___ level in arterial blood

abnormally high HCO3

respiratory acidosis is caused by ___ level in arterial blood

abnormally high CO2 pressure

respiratory alkalosis is caused by ___ level in arterial blood

abnormally low CO2 pressure

causes of metabolic acidosis

Severe diarrhea, renal dysfunction, accumulation of acids other than carbonic acid (e.g. ketosis), kidney failure.

causes of metabolic alkalosis

Excessive intake of alkaline drugs, excessive vomiting, endocrine disorders, severe dehydration

causes of respiratory acidosis

↓ movement of CO2 from blood to alveoli.

Emphysema, pulmonary edema, injury to respiratory center of medulla oblongata, airway obstruction, decreased breathing

causes of respiratory alkalosis

: ↑ movement of CO2 from blood to alveoli.

High altitude, stroke, severe anxiety

Used for wet dressings, irrigations, injections for fluid and electrolyte replenishment,

0.9% w/v isotonic NaCl

Maintenance therapy for patients unable to take fluids for 1 to 3 days

hypotonic NaCl

Used when there is loss of sodium in an excess of water.

hypertonic NaCl

effect of hypertonic NaCl when taken orally

vomiting, possible sharp increase in sodium blood level

T or F: KCl tablets are recommended for K replacement

false

Contraindications of KCl

• Impaired renal function • Acute dehydration

Mode of intake for calcium replacement solutions

All are ideally taken orally EXCEPT CaCl2 which must injected slowly and calcium gluconate which can be taken intravenously and orally

calcium replacement solution that can act as an antacid

tribasic calcium phosphate

why is it not ideal to give calcium gluconate intramuscularly?

can cause abscess formation

why must CaCl2 be injected slowly?

irritating to veins

other name for MgSO4

Epsom Salt

uses/indications of epsom salt

• For prevention & treatment of Eclampsia.

• Hypomagnesemia.

• Constipation.

principal bicarbonate of drug use

NaHCO3

uses of NaHCO3 in acid-base therapy

• Combat gastric hyperacidity

• Combat systemic acidosis

» Used for methanol poisoning.

• Miscellaneous uses:

» Lessens the acidity of the urine → prevents crystallization of some drugs.

uses of sodium citrate in acid-base therapy

Anti-coagulant for whole blood.

Can restore bicarbonate reserves in the body.

Has diuretic effect due to increased body salt concentration

uses of sodium lactate in acid-base therapy

treatment of metabolic acidosis

—> cannot be used in lactic acidosis

pharmacological categories of NH4Cl

• Acid-base equilibrium of the body • Diuretic effect • Expectorant effect

it is a systemic acidifier in acid-base therapy

ammonium chloride

why are renal failure and liver failure contraindicated in NH4Cl?

risks of ammonium toxicity

• Intended to supply normal requirements for water and electrolytes.

• Should contain at least 5% dextrose solution.

Maintenance therapy products

Used when there is heavy loss of water and electrolytes (e.g., prolonged fever, diarrhea).

Replacement therapy products