Download MBBS Water and Electrolyte Balance Lecture PPT

--- Content provided by⁠ FirstRanker.com ---

Water is a medium for a vast number of biochemical

reactions that occur each moment, which form the

--- Content provided by‍ FirstRanker.com ---

basis of life

Water solubilises various biomolecules such as

proteins, nucleic acid and carbohydrates by forming

--- Content provided by‍ FirstRanker.com ---

hydrogen bond with them

Apart from providing an aqueous medium, water act

--- Content provided by⁠ FirstRanker.com ---

as strong nucleophile,directly participates as reactant

in various metabolic reaction

Water plays an important role in regulating body

--- Content provided by‍ FirstRanker.com ---

temperature


ELECTROLYTE ? DISTRIBUTION AND

--- Content provided by​ FirstRanker.com ---

BALANCE

Electrolytes are the substances which readily

--- Content provided by‍ FirstRanker.com ---

dissociate in solution and exist in ionic form i.e.

positively and negatively charged ions

Electrolytes are well distributed in body fluids to

--- Content provided by‌ FirstRanker.com ---

maintain osmotic equilibrium and water balance

Sodium is the principal cation of ECF,while potassium

--- Content provided by‌ FirstRanker.com ---

is the chief cation of ICF

Chloride and bicarbonate are the principal anion of

ECF,while phosphate is the chief anion of ICF

--- Content provided by‌ FirstRanker.com ---

The total concentration of cations and anions in each body

compartment is equal in order to maintain electrical

neutrality

--- Content provided by⁠ FirstRanker.com ---

The concentration of molecules in body fluids are mainly

expressed in terms of osmolality and osmolarity

--- Content provided by‍ FirstRanker.com ---

Osmolality : osmotic pressure exerted by number of moles

per kg of solvent

Osmolarity :osmotic pressure exerted by number of moles

--- Content provided by‍ FirstRanker.com ---

per litre of solution

The osmolality of plasma is in the range of 280-

--- Content provided by​ FirstRanker.com ---

300mosmo/kg

Sodium and its associated anions makes the

largest contribution to plasma osmolality

--- Content provided by‌ FirstRanker.com ---

It is measured by osmometer

osmolality = 2(Na+)+2(K+)+(glucose)+(urea)
Regulation of water and electrolyte

--- Content provided by​ FirstRanker.com ---

balance

Kidney play a major role in the regulation of

--- Content provided by‌ FirstRanker.com ---

electrolyte and water balance

The regulation is maintained by the hormones

aldosterone,ADH and renin-angiotensin

--- Content provided by⁠ FirstRanker.com ---

Aldosterone is a mineralcorticoid produced by the

zona glomerulosa of the adrenal cortex in response to

--- Content provided by‌ FirstRanker.com ---

angiotensin II derived by the action of renin
Renin-Angiotensin system
The secretion of aldosterone is regulated by the renin-

angiotensin system

--- Content provided by​ FirstRanker.com ---

When there is fall in ECF volume, renal plasma flow

decreases and this would be sensed by the

--- Content provided by FirstRanker.com ---

juxtaglomerular apparatus of the nephron which

secrete renin

--- Content provided by⁠ FirstRanker.com ---

Hyponatremia

Hyponatremia is defined as decrease plasma sodium

--- Content provided by FirstRanker.com ---

concentration below 136 meq/l

Hyponatremia typically manifests itself clinically as

nausea,genarlized weakness and mental confusion at

--- Content provided by⁠ FirstRanker.com ---

value below 120 meq/l

The central nervous system symptoms are primarily

--- Content provided by​ FirstRanker.com ---

caused by movement of water in to cells to maintain

osomotic balance and thus swelling of CNS cells

Hyposmotic Hyponatremia

--- Content provided by⁠ FirstRanker.com ---

Hyperosmotic Hyponatremia
Isosmotic Hyponatremia
Hyposmotic Hyponatremia

This type of hyponatremia can be result of either

--- Content provided by‌ FirstRanker.com ---

excess loss of sodium (depletional hyponatremia) or

increased ECF volume (dilutional hyponatremia)

--- Content provided by⁠ FirstRanker.com ---

Differentiating these initially requires a clinical

assessment of TBW and ECF volume

Depletional hyponatremia is almost accompanied by a

--- Content provided by⁠ FirstRanker.com ---

loss of ECF water, but to a lesser extent than sodium

loss

--- Content provided by​ FirstRanker.com ---

Dilutional hyponatremia is a result

of excess water retention and can

often be detected during physical

--- Content provided by‌ FirstRanker.com ---

examination as presence of weight

gain or edema

--- Content provided by‌ FirstRanker.com ---

Hyperosmotic Hyponatremia

Hyponatremia occurs with an increased amount of

other solutes in the ECF,causing an extracellular shift

--- Content provided by‌ FirstRanker.com ---

of water or intracellular shift of sodium to maintain

osmotic balance between ECF and ICF

--- Content provided by FirstRanker.com ---

The most common cause of this type of hyponatremia

is severe hyperglycemia

As a general rule,the Na+decreases by 1.6 mmoles/l

--- Content provided by‌ FirstRanker.com ---

for every 100 mg/dl increase of glucose above 100

mg/dl

--- Content provided by‌ FirstRanker.com ---

The clinical use of mannitol for osmotic diuresis can

have similar effect
Isosmotic Hyponatremia

--- Content provided by​ FirstRanker.com ---

If the measured sodium concentration in plasma is

decreased,but measured plasma

osmolality,glucose,urea are normal ,the only

--- Content provided by FirstRanker.com ---

explanation is pseudohyponatremia

This occurs when sodium is measured by an

--- Content provided by FirstRanker.com ---

indirect ion selective electrode in patient with

severe hyperlipidemia or in state of

hyperproteinemia caused due to multiple

--- Content provided by​ FirstRanker.com ---

myeloma
Hypernatremia

Hypernatremia (plasma Na+>150mmol/l) is always

--- Content provided by​ FirstRanker.com ---

hyperosmolar

Symptoms of hypernatremia is primarly neurological

--- Content provided by⁠ FirstRanker.com ---

and include tremors,irratibility,ataxia,confusion and

coma

Most cases of hypernatremia occurs in patients with

--- Content provided by‌ FirstRanker.com ---

altered mental status or infants,both of whom may

have difficulty in rehydrating themselves despite a

--- Content provided by​ FirstRanker.com ---

normal thirst reflex


Hypovolemic Hypernatremia

--- Content provided by⁠ FirstRanker.com ---

Normovolemic Hypernatremia

Hypervolemic Hypernatremia

--- Content provided by FirstRanker.com ---

Hypokalemia

Plasma potassium level less than 3.5 meq/l is called

--- Content provided by FirstRanker.com ---

hypokalemia

Characterized by muscle weakness,irratibility and

paralysis

--- Content provided by‍ FirstRanker.com ---

Plasma potassium less than 3 meq/l are associated

with serious neuromuscular symptoms

--- Content provided by⁠ FirstRanker.com ---

Tachycardia along with flattened T waves is seen in

ECG

Caused due to redistribution of ECF k+ in to ICF or due

--- Content provided by⁠ FirstRanker.com ---

to true k+ deficit(loss of potassium rich body fluid or

decreased intake of k+ )
Redistribution

--- Content provided by​ FirstRanker.com ---

Insulin therapy for diabetic hyperglycemia
Metabolic alkalosis
Acute leukemia

True potassium deficit

--- Content provided by​ FirstRanker.com ---

Extrarenal loss in diarrhea or excessive sweating
Renal loss in acute tubular necrosis
Mineralcorticoid excess
Cushing syndrome
Hyperkalemia

--- Content provided by FirstRanker.com ---

Plasma potassium greater than 5 mmoles/l is called

hyperkalemia

--- Content provided by‌ FirstRanker.com ---

Characterized by mental

confusion,weakness,tingling,flaccid paralysis of the

extremities

--- Content provided by‍ FirstRanker.com ---

Cardiac effects of hyperkalemia including bradycardia and

conduction defect evident on ECG by prolonged PR and

--- Content provided by⁠ FirstRanker.com ---

QRS interval and peaked T waves

Level above 7 mmoles/l leads to cardiac arrest
Pseudohyperkalemia
Hemolysis

--- Content provided by‍ FirstRanker.com ---

Thrombocytosis(>106/l)
Leukocytosis(>105/l)

Redistribution
Metabolic acidosis

--- Content provided by FirstRanker.com ---

Dehydration
Massive tissue hypoxia
Insulin deficiency
Potassium retention
Acute renal disease and end stage renal failure

--- Content provided by‌ FirstRanker.com ---

Addison disease

ACE inhibitors

--- Content provided by⁠ FirstRanker.com ---

Potassiun sparing diuretics (spironolactone,Amiloride)