Homeostasis

• The ability of living systems to maintain a

steady and uniform internal environment in
response to the environmental changes to
allow the normal functioning of the systems.

• Homeostasis = maintenance of constant

parameters of internal environment
• Homeostasis is a necessary process that
maintains the internal environment of living
beings at optimum levels so that normal
physiological processes can take place
smoothly.
 Homeostasis

Involves various internal variables of the living system

like:
• Body water (water balance)
• The concentration of different ions (Electrolyte
balance)
• pH of various fluids (Acid-Base balance)
• body temperature
• Blood sugar level
This balance is called Homeostasis.
 Homeostasis
• cellular function and biological processes
require a fluid medium with a carefully
controlled composition
• A number of regulatory mechanisms are employed to
resist changes in the body against environmental and
bodily factors.

• It results in a dynamic equilibrium, where continuous

changes keep on taking place, and yet steady
conditions are maintained.
Homeostasis Normal physiological
processes

Homeostasis
death
disease

Medical intervention
 ‫بسم الله الرحمن‬
‫الرحيم‬
‫َوَجَعْلَنا ِمَن اْلَم اِء ُكَّل‬
‫َش ْي ٍء َح ٍّي‬
‫صدق الله العظيم‬
Water & Electrolyte Balance
In Anaesthesia for medical students

By Dr Hisham MF Anwer
Professor of Anaesthesiology
Body water
 Body water function
• Maintains homeostasis
• Lubricant to all tissues
• Essential for cellular function and metabolism
• Media for transportation
• helps regulate and maintain body temperature
• Important for getting rid of various toxic elements from
the body
• Cushions joints and CNS to prevent shocks and trauma
Basically everything
 Body water

Obesity decreases the percentage of water in the

body, sometimes to as low as 45 percent"
Water content in different body parts
 Body water
• The average for most healthy persons is 60% of
the body weight.
• Fat tissue contains significantly less water (only
10%) than muscle and other tissues (70%).
• As an average females have a low body water
percentage compared to males.
• Sedentary, overweight persons contain only 50-
55 % water dependent on the body fat content.
 Fluid Compartments
The body's fluid separates into two main
compartments:
• Intracellular fluid volume (ICFV)
• extracellular fluid volume (ECFV)

separated from one another by cell membranes

 Semipermeable Membrane
(selectively permeable) (partially permeable )
(differentially permeable) membrane

only certain molecules can pass through

• Biological (two sheets of phospholipid)

• Artificial (designed for the purposes of filtration)
Osmosis and Diffusion
Semipermeable Membrane

The electrochemical gradient is a combination of the

concentration gradient and the electrical potential.
 Transport across cell membranes
Passive:
• Osmosis.
• Diffusion: simple or facilitated
Active:
• Active transport: against conc. gradient
(carrier protein, consumes energy)
• Bulk transport (endocytosis and exocytosis)
 Osmosis
• The diffusion of water from regions of
higher concentration to regions of lower
concentration, along an osmotic gradient
across a semi-permeable membrane

Diffusion
• Movement of molecules or ions from a region
of high conc. to low conc.

Large polar molecules (glucose & amino acids) and ions (Na+ & Cl-) cannot
diffuse through phospholipid memb.
 Facilitated Diffusion
Protein molecules exist in membranes To
facilitate diffusion:

• Channel protein: forms a tunnel through the

bilayer. (Ex. Ions)

• Carrier proteins: change shape to help

molecules to move in and out the cell. (Ex. G.)
Transport across cell membranes
Active Transport across cell membranes

The Na -K -pump
+ +

• Located in the cell membrane, maintains the

high intracellular K+ and the low intracellular
Na+.
• The energy of the terminal phosphate bond of
ATP is used to actively extrude Na+ and pump
K+ into the cell.
The Sodium-Potassium Pump
 The Na -K -pump
+ +

• Virtually every cell membrane in the body

contains the Na+- K+-pump, which maintains the
low intracellular Na+-concentration and develops
the negative, intracellular voltage.

• The K+ -permeability is around 50 times larger

than the Na+ -permeability, so the RMP of normal
myocardial cells (typically: -90 mV) almost equals
the equilibrium potential for K+ (-94 mV).
Resting Membrane Potential
 The Resting Membrane Potential

The negative charge across the membrane that

would be necessary to oppose the movement
of K+ down its concentration gradient
Electro-chemical gradient
 Fluid Compartments
• Extracellular fluid have high concentrations of
sodium, chloride, and bicarbonate ions, and
lesser amounts of potassium, calcium,
magnesium, phosphate, and sulfate ions.

• Intracellular fluid has high concentrations of

potassium, phosphate, and magnesium ions,
and lesser amounts of sodium, chloride, and
bicarbonate ions.
 ELECTROLYTE DISTRIBUTION
Extracellular Intracellular
Electrolyte Function
meq/liter meq/liter
fluid balance, osmotic
Sodium 142 10
pressure
Neuromuscular
Potassium 5 100 excitability
acid-base balance
Calcium 5 - bones, blood clotting
Magnesium 2 123 enzymes
Total Positive ions 154 205

Electrolyte Distribution
Extracellular Intracellular
Electrolyte Function
meq/liter meq/liter
fluid balance, osmotic
Chloride 105 2
pressure

Bicarbonate 24 8 acid-base balance

Proteins 16 55 osmotic pressure

Phosphate 2 149 energy storage
Sulfate 1 - protein metabolism
Total Negative ions 154 205
 Fluid Compartments
• The intracellular and extracellular
compartments are separated from one
another by the plasma membrane of the cells.

• The extracellular compartments

(interstitial/plasma) are separated by a layer
of endothelial cells surrounded by a basement
membrane; the capillaries.
Fluid Movement between Compartments
 Fluid Compartments
Total body water
(60%
bodyweight)
70 kgm
2/3 1/3

20% extracellular
40% intracellular fluid
fluid
14 kgm
28kgm

3/4 1/4

15% 5%
interstitia plasma
l volume

10.5 kgm 3.5 kgm

Fluid Compartments
 Fluid Compartments
• The three major body fluid compartments are
the intracellular fluid volume (ICV), the
interstitial fluid volume (ISV) and the vascular
space.

• Water permeable membranes separate the three

compartments, so that they contain almost the
same number of osmotically active particles per
kg. They are said to be isosmolal, because they
have the same osmolality.
 Fluid Compartments
• Selectively permeable membranes separate
body fluids into distinct compartments.

• Plasma membranes of individual cells

separate ICF from ECF
• blood vessel walls separate blood plasma
from interstitial fluid.
 The intracellular fluid (ICF)
• Very stable & closely regulated.
• If the amount of water inside a cell falls to a
value that is too low, the cytosol becomes too
concentrated with solutes to carry on normal
cellular activities;
• if too much water enters a cell, the cell may
burst and be destroyed.
• ICF volume changes result from alterations in
the osmolarity of the ECF
 Interstitial Fluid IF
• The IF bathes all the cells in the body.
• Has a low protein concentration (in
comparison to plasma)

• Link between the ICF and the intravascular

compartment
• Oxygen, nutrients, wastes and chemical
messengers all pass through the ISF
 Plasma
• The ‘interstitial fluid of the blood’
• higher protein content (in contrast to IF)
• high bulk flow (transport function)
 Osmotic equilibrium
• •Maintained between ECF and ICF.
• •Free flow of water through cell membrane.
• •Osmolality of body fluids-300 m osm /L
• •Isotonicity, hypotonicity, hypertonicity
• •Isotonic solutions
• –0.9% NaCl
• –5% Glucose
Fluid Movement between Compartments
 Movement of Fluid between
Compartments
• Hydrostatic pressure and osmotic pressure
regulate the movement of water and
electrolytes from one compartment to
another.
• Although the composition of body fluids varies
from one compartment to another, the total
solute concentrations and water amounts are
normally equal.
 Movement of Fluid between
Compartments
• Water moves from one compartment to
another due to osmosis.
• Osmosis is chiefly influenced by dissolved
solutes in fluids. Most of these solutes are
electrolytes.

• Plasma Osmolality = (2XNa) + Glucose mg%/18 + BUN/2.8

 Movement of Fluid between
Compartments
• The net movement of water into or out of cells is
dictated by the osmotic pressure gradient.

• The most abundant osmoles in the extracellular fluid

are sodium (and the accompanying anions chloride
and bicarbonate), glucose, and urea. They are the
main determinants of plasma osmolality

• Plasma Osmolality = (2XNa) + Glucose mg%/18 + BUN/2.8

 Osmolarity and Osmolality
• Osmolarity is the number of solute particles
per 1 L of solvent. (temperature dependent)
• osmolality is the number of solute particles in
1 kg of solvent.
• Osmolality is a measure of the number of
particles present in solution and is
independent of the size or weight of the
particles.

• the osmole is the number of moles of solute

that contribute to the osmotic pressure of a
solution.

• 1 mol/L NaCl corresponds to an osmolarity of 2 osmol/L.

• 1 mol/L CaCl2, gives a solution of 3 osmol/L
 Fluid Movement between IF & IC

• All compartments have almost the same osmolality

300 mOsmol* kg-1 of water.

• Nutrients diffuse into the cell with waste products

coming out into the interstitial space.

• The thin cell membrane cannot carry any important

hydrostatic gradient. Water passes freely between
the extra- and intra-cellular compartment, as osmotic
forces govern its distribution and the membranes are
water permeable.
 Fluid Movement between IV & IF
Capillaries act rather like a leaky hosepipe; although the bulk of
the fluid continues along the pipe, the pressure forces some out
of the walls.
Arterial side
Venous side
BHP = +30mmHg
BHP = +15mmHg
IFOP = +6 mmHg
IFOP = +6 mmHg
BOP = -28 mmHg
BOP = -28 mmHg
IFHP = - 0 mmHg
IFHP = - 0 mmHg
+ 8 mmHg
- 7 mmHg

The balance of hydrostatic and osmotic forces causing

movement out and into the capillaries are known as
Starling forces.
 interstitial fluid volume
• Lymph is considered as a part of the IF. The
lymphatic system returns protein and excess IF
to the circulation.

• Edema is a clinical condition where the

interstitial fluid volume (IF) is abnormally large.
Edema
 Movement of body fluids between the
compartments
• Bulk flow is the movement of both solvent and solute into the
interstitial space. Pressures acting to move substances out of
the capillary include blood hydrostatic pressure (BHP) and
interstitial fluid osmotic pressure (IFOP). Blood colloid osmotic
pressure (BCOP) and interstitial fluid hydrostatic pressure act
to push substances into the capillary. At the arterial end of the
capillary the sum of the outward moving pressures is
dominant and substances move into the interstitial fluid
(filtration). At the venous end the inward pressure is dominant
and the substances move into the capillary (reabsorption).
• Aldosterone, ANP and ADH regulate sodium levels within the
body, whilst aldosterone can be said to regulate potassium.
 Functional classification system
• The First space : Intravascular space (within
vessels)
• The Second space: the extravascular space (the
interstitial and intracellular spaces)
• The Third space: does not normally collect in
large amounts
Ex: the peritoneal cavity and pleural cavity.
• Fluid in the second space is physiologically more
active with the intravascular ("first") space than
third space fluid is.

• Fluid in the second space is more readily

available for the body to use (such as for the
correction of ionic imbalances in other
compartments) than fluid in the third space.

• Third space: where any significant fluid

collection is physiologically nonfunctional .
 Third space loss
• Clinically, its actual volume of fluid is difficult to
accurately quantify.
• In long extensive operations is accounted by tissue
edema and evaporation.
• Also can refer to ascites and pleural effusions.
• In severe burns: fluids may pool on the burn site
(lying outside of the interstitial tissue) exposed to
evaporation.
• With pancreatitis or ileus, fluids may "leak out" into
the peritoneal cavity.
 Water Balance
water intake equals water output
Daily water gain Daily water loss

• 60% from drinking, • 60% urine

• 30% from moist foods, • 5% feces
• 10% from the water of • 5% sweat
metabolism. • 15% insensible (skin)
• 15% insensible (lungs)
 Water Balance
Daily Intake of Water
• Fluids Ingested (liquids/water in diet) – 2100 ml
• From metabolism – 200 ml
Net Intake = 2300 ml

Daily output of Water

• Insensible (skin) – 350 ml •
• Insensible (lungs) – 350 ml
• Sweat – 100 ml
• Feces – 100 ml
• Urine – 1400 ml
Net Output = 2300 ml
Homeostasis of body water
 Regulation of Water Intake
• The thirst mechanism is the primary regulator
of water intake.
• The thirst mechanism derives from the
osmotic pressure of extracellular fluids and a
thirst center in the hypothalamus.
• Once water is taken in, the resulting distention
of the stomach will inhibit the thirst
mechanism.
 dehydration stimulates the thirst reflex in
three ways:
• The level of saliva drops resulting in a dry mucosa in
the mouth and pharynx;
• there is an increase in blood osmotic pressure which
stimulates osmoreceptors in the hypothalamus;
• there is a drop in blood volume, which leads to the
renin/angiotensin II pathway stimulating the thirst
centre in the hypothalamus.
• This reflex is not always reliable in young children,
the elderly, or those in a confused mental state
 Water Output
• Water is lost in urine, feces, perspiration,
evaporation from skin (insensible
perspiration), and from the lungs during
breathing.
• The route of water loss depends on
temperature, relative humidity, and physical
exercise.
 Fluid loss
• Three hormones regulate fluid loss:
Antidiuretic Hormone (ADH), Aldosterone, and
Atrial Natriuretic Peptide (ANP).
 Regulation of Water Output
• The distal convoluted tubules and collecting
ducts of the nephrons regulate water output.
• Antidiurectic hormone from the posterior
pituitary causes a reduction in the amount of
water lost in the urine.
• When drinking adequate water, the ADH
mechanism is inhibited, and more water is
expelled in urine.
 Body Water Homeostasis
• The major effector mechanisms are:
a) Control of Water Input : Thirst
Thirst is a mechanism for adjusting water
input via the GIT
b) Control of Water Output : ADH & the Kidney
ADH provides a mechanism for adjusting
water output via the kidney.
 Stimuli to Thirst
• The 4 major stimuli to thirst are:
a) Hypertonicity: Cellular dehydration acts via an
osmoreceptor mechanism in the hypothalamus
b) Hypovolaemia: Low volume is sensed via the low
pressure baroreceptors in the great veins and right
atrium
c) Hypotension: The high pressure baroreceptors in
carotid sinus & aorta provide the sensors for this
input
d) Angiotensin II: This is produced consequent to the
release of renin by the kidney (eg in response to renal
hypotension)
 Dehydration
• Is a clinical condition with an abnormal
reduction of one or more of the major fluid
compartments (i.e, total body water with
shrinkage of blood volume or ISF).
 Dehydration
• Dehydration occurs when water intake is less
than water loss.

• Symptoms range from mild to life-threatening.

• The young and the elderly are especially

susceptible to dehydration.
 Mild Dehydration
water losses between 1% and 2%
Symptoms:
• Thirst, decreased urine volume, abnormally
dark urine, unexplained tiredness, irritability,
headache, dry mouth, dizzines when standing
due to orthostatic hypotension, and in some
cases insomnia.
 moderate to severe
dehydration
symptoms
• No urine output at all, lethargy or extreme sleepiness, seizures,
sunken fontanel (soft spot) in infants, fainting, and sunken eyes.
• The symptoms become increasingly severe with greater water
loss.
• heart and respiration rates begin to increase to compensate for
decreased plasma volume.
• body temperature may rise because of decreased sweating
• At around 5% to 6% water loss: Pt is groggy or sleepy,
experience headaches or nausea, and may feel tingling in limbs
(paresthesia).
 Severe Dehydration
• With 10% to 15% fluid loss, muscles may
become spastic, skin may wrinkle (decreased
skin turgor), vision may dim, urination will be
greatly reduced and may become painful, and
delirium may begin.
• Losses greater than 15% are usually fatal.
decreased skin turgor
 Electrolyte Balance
• Fluid balance is implicitly linked to electrolyte
balance. Electrolytes establish osmotic
pressure and are largely responsible for the
movement of fluids.
Definitions
 Electrolytes
• Electrolytes are minerals that carry an electric
charge when dissolved in water

• They conduct electricity through the movement

of those ions, but not conducting electrons.
 Mole
• The amount of a substance that contains the
number of molecules equal to Avogadro's
number.

• Avogadro's number - this is the number of

molecules in one mole of a substance (i.e.
6.022 x 1023)
 Mole
Is just a number : 6.022 x 1023 (Avogadro's number)

• The mass in grams of one mole of a substance is

the same as the number of atomic mass units in
one molecule of that substance

(i.e. the molecular weight of the substance expressed

as grams).
 Mole
• Molecular weight in grams.
• 1Mole of Carbon (12C)= 12 grams
• 1 Mole of Oxygen (16O2) = 16 grams
• 1 Mole of Hydrogen (1H2) = 1 gram
• 1 Mole of Sodium (23Na) = 23 grams
 Molarity & Molality
• Molarity of a solution is the number of moles
of solute per litre of solution

• Molality of a solution is the number of moles

of a solute per kilogram of solvent
 Equivalent weight
• The mass which combines with or displaces
1.008 gram of hydrogen or 8.0 grams of
oxygen or 35.5 grams of chlorine. (These values
correspond to the atomic weight divided by the usual valence)

Equivalent weight = Molecular weight / Valence factor

 Equivalent weight
• For some ione: Equivalent = Number of moles
needed to balance the charge of 1 Mole of 1
opposite charged monovalent.
• 1 Equivalent of K = 1 Mole of K
• 1 Equivalent of Ca = ½ Mole of Ca
• 1 Mole of Ca = 2 Equivalents
• 1 Mole of N2 = 3 Equvalent.

Equivalent weight = Molecular weight / Valence factor

• Molar concentration (molarity) is the number of moles of
a substance totally dissolved per litre (l) of solution - often
given in mmol per l or mM. One mol of a substance is the
amount of that substance containing Avogadros
number, 6.022 *1023 molecules per mol.
• Molality is the number of mol totally dissolved substance
per kg of solvent, frequently water.
• Normality of a solution is the number of equivalents per l
(Eq l-1).
• Osmolality is a measure of the osmotic active particles in
one kg of water.
• Osmolarity is the number of osmotically active particles
dissolved in a litre of solution.
 definitions
• Mole - A mole is the amount of a substance that contains the number of
molecules equal to Avogadro's number. The mass in grams of one mole of
a substance is the same as the number of atomic mass units in one
molecule of that substance (ie the molecular weight of the substance
expressed as grams). The mole (symbol: mol) is the base unit in the SI
system for the amount of a substance
• Avogadro's number - this is the number of molecules in one mole of a
substance (ie 6.022 x 1023)
• Molality of a solution is the number of moles of a solute per kilogram of
solvent
• Molarity of a solution is the number of moles of solute per litre of solution
• Osmole - This is the amount of a substance that yields, in ideal solution,
that number of particles (Avogadro’s number) that would depress the
freezing point of the solvent by 1.86K
• Osmolality of a solution is the number of osmoles of solute per kilogram
of solvent
• Osmolarity of a solution is the number of osmoles of solute per litre of
solution
 Electrolyte Balance
• The electrolytes of greatest importance to
cellular metabolism are sodium, potassium,
calcium, magnesium, chloride, sulfate,
phosphate, bicarbonate, and hydrogen ions.
• the action of aldosterone on the kidneys
regulates sodium reabsorption
• Aldosterone also regulates potassium ions;
potassium ions are excreted when sodium
ions are conserved.
 Electrolyte Balance
• Calcium concentration is regulated, in part, by
parathyroid hormone, which increases the
concentrations of calcium and phosphate ions
in extracellular fluids.
• Generally, the regulatory mechanisms that
control positively charged ions secondarily
control the concentrations of anions.
 Sodium
• One of the most important electrolytes in the
extracellular fluid

• An osmotically active cation responsible for

maintaining the extracellular fluid volume

• Sodium regulation occurs in the kidneys by the

action of the hormone aldosterone
 Sodium Balance
• Normal value: 135-145 mmol / L
• Daily requirements: 1-2 mmol/kg/d
• Na balance: intake=excretion

• Renal excretion controlled by aldosterone,

atrial natriuric peptide, angiotensin II, and
alpha adrenergic stimulation.
 Hypernatremia
• Serum Na >145mmol/l
• Always with Hyperosmolarity
• Causes:
• Water deficiency: Inadequate intake or
excessive loss (kidney D.I., sweat, diarrhea,..)
• Na excess (rare): Renal failure, hypertonic
saline, iatrogenic.
 Hypernatremia
Manifestations: (due to cellular dehydration)
• Thirst
• Neurological dysfunction due to dehydration of
brain cells
• Sleeping difficulty, and feeling restless
• Lethargy, Mental changes
• Hyperreflexia
• hypovolemia
• seizures
 Hypernatremia
Management:
• Na restriction
• Water administration: oral or Dextrose 5%
• Increase Na excretion (diuretics)
• Treatment of the cause (Diabetes insipidus)
 Calculation of water deficit
• Normal body Na x Normal body water = Actual body Na x Actual body water

• Water deficit = Current Total Body water x { ( Serum [Na] ÷ 140 ) – 1}

 Hyponatremia

• Serum Na <135 mmol/l

• The most common electrolyte disorder in

hospitalised patient.

• Most often resulting from excess total body

water (Dilutional hyponatraemia)
 Hyponatremia
Causes:
Water excess:
• increase intake: Psychogenic, TURP, iatrogenic.
• Inadequate water excretion: renal failura, heart
failura,Hypothyroidism, Excess ADH.

Na deficiency:
• Inadequate intake, external loss(sweat, GIT) and
renal loss (diuretics, aldosterone deficiency)
 Hyponatremia

• Signs/Symptoms:
• Depends on the rate and severity.
• Serious manifestations when S.Na<120mmol/l
• Mostly due to cerebral edema
 Clinical manifestations of
Hyponatremia
• Neurological symptoms
Lethargy, headache, delirium, confusion,
apprehension, depressed reflexes, seizures and
coma
• Muscle symptoms
Cramps, weakness, fatigue
• Gastrointestinal symptoms
Nausea, vomiting, abdominal cramps, and diarrhea
 Hyponatremia
Management:
• Correct primary cause
• Mild (Na<135mmol/l):Increase Na intake and
water restriction
• Moderate(Na<130):saline0.9%, water restriction.
• Severe (Na<120)+mental changes:
• N.S. or hypertonic saline, diuretics
• Avoid rapid correction of Serum Na.
 Hyponatremia
Calculation of Na deficit:
• Sodium deficit = Total body water (TBW) ×
(desired S.Na – actual S.Na)

Rapid sodium corrections can have serious

consequences like cerebral edema and osmotic
demyelination syndrome.
 Potassium Homeostasis
• I.C. Conc : 150mmol/l
• E.C. (Serum) Conc: 3.5-5 mmol/l

• Disturbance of water balance have little effect

on K level.
• Acid base status markedly affects S. K level
(enter the cells in exchange with H+)
 Potassium Homeostasis
• Achieved by alterations in renal excretion of
potassium in response to variations in intake.

• Any rise in serum [K+] immediately results in a

marked rise in K+-secretion (in the renal distal tubules and
collecting ducts)

• This transport mechanism is controlled by

aldosterone and by K+ (Aldosterone stimulates the secretion of K+
and H by the renal distal tubules and collecting ducts).
+
 K  Homeostasis
+

• The daily dietary intake of potassium varies

with the amount of fruit and vegetables
consumed.
• About 75-150 mmol is daily absorbed in the
intestine.
• A high urinary K+ is indicative of a high total
body K+ or a high intake of K+
 K 
+

• In myocardial cells, as in skeletal muscle and

nerve cells, K+ plays a major role in
determining the resting membrane potential
(RMP), and K+ is important for optimal
operation of enzymatic processes.
 Hyperkalemia
• Increased intake: Rapid B.Transfusion, K
supplements.
• Decreased excretion: Renal Failure, Potassium
sparing diuretics, Aldosterone deficiency, A/C
inhibitors.
• Extracellular redistribution: acidosis, cellular
destruction, suxamethonium.
 Clinical manifestations of Hyperkalemia
• Many individuals are asymptomatic.
• symptoms are nonspecific and predominantly
related to muscular or cardiac function.
• The most common complaints are weakness
and fatigue.
• Occasionally, frank muscle paralysis or
shortness of breath.
Also, may have:
• palpitations or chest pain.
• nausea, vomiting, and paresthesias.
 Clinical manifestations of Hyperkalemia

The most serious manifestations of hyperkalemia are

• muscle weakness or paralysis

• cardiac conduction abnormalities
• cardiac arrhythmias
 Cardiac manifestations of Hyperkalemia

Change in ECG
• Tall peaked T wave
• Prolonged PR interval
• Decreased P wave
• Widening QRS complex.

Dysrhythmias
Bradycardia , heart block, cardiac arrest
 Management of Hyperkalemia

• Eliminate the cause: Stop K intake

• Calcium cloride 10% IV
• Transfere K inside the cells: Insuline/Glucose,
NaHCO3, Hyperventilation, B2 adrinergic
stimulants.
• Removal of body K: Diuretics, K exchange
resine (oral or enema), Hemodialysis.
 Hypokalaemia
• Serum K <3.5mmol/l
Causes:
• Decrease intake
• Shift into cells: Correction of acidosis,
Insuline/glucose, Alkalosis, hypothermia.
• Increase loss: Diuretics, Hyper aldosteronism,
Renal tubular acidosis, Vomiting, NG
suctioning, Fistula drainage, Mg deficiency.
 Manifestations of Hypokalemia

• Neuro-muscular: Weakness, fatigue, muscle

twitching, hyporeflexia.
• Smooth muscles: constipation, Distention,
Ileus.
• CVS: Dysrhythmias.
• ECG changes: U wave, ST depression, T wave
depression
• Digitalis toxicity.
 Management of Hypokalemia
• Correct precipitating factors: alkalosis, …
• Oral or IV K chloride.
• When < 2.5 mmol/l or paralysis or ECG
changes: IV KCL at rate 20 – 40 mmol/h under
ECG monitoring
 Calcium
• involved in skeletal mineralization, contraction of
muscles, the transmission of nerve impulses, blood
clotting, and secretion of hormones.
• It is mostly present in the extracellular fluid.
• Absorption of calcium in the intestine is primarily under
the control of the hormonally active form of vitamin D
• Parathyroid hormone also regulates calcium secretion
in the distal tubule of kidneys.
• Calcitonin acts on bone cells to increase the calcium
levels in the blood.
 Hypocalcemia
• serum total calcium levels are less than 8.8
mg/dl, as in
• vitamin D deficiency or
• hypoparathyroidism.
Clinical manifestations of hypocalcemia

According to severity, the rate of development

and chronicity.

• Acute: tetany, papilledema, and seizures.

• Chronic: ectodermal and dental changes,

cataracts, basal ganglia calcification, and
extrapyramidal disorders
 Tetany
Neuromuscular irritability
• Mild: perioral numbness, paresthesias of the
hands and feet, muscle cramps
• Severe: carpopedal spasm, laryngospasm, and
focal or generalized seizures.
• less specific symptoms: fatigue, hyperirritability,
anxiety, and depression.
 Hypercalcemia
• serum total calcium levels exceed 10.7 mg/dl,
• Usually a result of overactive parathyroid
glands. (primary hyperparathyroidism)
• Humoral hypercalcemia presents in
malignancy.
Clinical manifestations of hypercalcemia
• Excessive thirst and frequent urination.
• Stomach upset, nausea, vomiting and
constipation.
• Bone pain and muscle weakness.
• Confusion, lethargy and fatigue.
• Depression.
• Rarely, cardiac arrhythmia.
 Severe hypercalcemia can cause:
• Kidney failure.
• Abnormal heart rhythm (arrhythmia).
• Confusion.
• Coma.
 Bicarbonate
• The acid-base status of the blood drives
bicarbonate levels.
• The kidneys predominantly regulate
bicarbonate concentration and are responsible
for maintaining the acid-base balance
• Diarrhea usually results in loss of bicarbonate
 Magnesium
• an intracellular cation.
• Magnesium is mainly involved in ATP metabolism,
contraction and relaxation of muscles, proper
neurological functioning, and neurotransmitter release.
• Hypomagnesemia occurs when the serum magnesium
levels are less under 1.46 mg/dl.
• It can present with alcohol use disorder and
gastrointestinal and renal losses—
• ventricular arrhythmias, which include torsades de
pointes seen in hypo-magnesemia.
 Chloride
• anion found predominantly in the extracellular
fluid. The kidneys predominantly regulate
serum chloride levels.
• Hyperchloremia can occur due to
gastrointestinal bicarbonate loss.
• Hypochloremia presents
in gastrointestinal losses like vomiting or
excess water gain like congestive heart failure.
 Phosphorus
• an extracellular fluid cation.
• Eighty-five percent of the total body phosphorus is in the
bones and teeth in the form of hydroxyapatite; the soft
tissues contain the remaining 15%.
• Phosphate plays a crucial role in metabolic pathways. It is a
component of many metabolic intermediates and, most
importantly of adenosine triphosphate(ATPs) and
nucleotides.
• Phosphate is regulated simultaneously with calcium by
Vitamin D3, PTH, and calcitonin. The kidneys are the
primary avenue of phosphorus excretion.
 Phosphorus imbalance
due to three processes:
• dietary intake
• gastrointestinal disorders
• excretion by the kidneys