Disorders Of Water And Electrolyte Metabolism Flashcards
Plasma osmolality
2x Na plasma in mmol
When is body in water balance
Water intake= water output
Homeostasis of water and electrolytes maintained by
Kidney
Water transport
Ion transport
Biochemical factors regulating water and electrolyte balance
Thirst mechanism Antidiuretic hormone RAAS system Aldosterone ANP Kinins
Thirst mechanism
Lack of water->increased comc or osmolarity of plasma->stimulation of thirst centre in hypothalamus->to drink water-> water in body regulated
ADH mechanism
Lack of water in body->release of ADH->works on collection duct-> increases its permeability to water-> reabsorption of water-> scanty concentrated urine
RAAS mechanism kick in?
When volume and pressure of blood is lost. Ie from hearmmorhage, vomiting, diarrheal . Mechanisms that lead to drop in BP
Where is vasopressin secreted from?
Posterior pituitary
RAAS mechanism?
Decreased BP->stimulation of receptors in juxtaglerular apparatus->release of renin->formation of angiotensin 2->contriction of afferent arteriole->restoration of BP as pressure increases.
Angiotensin 2 can also release aldosterone->causes reabsortiom of sodium amd water-> lowers irine output
Aldosterone
Increases k+ losses im urine
Hyperkalemia
Induces release of aldosterone
Aldosterone
Acts on distal comvoluted tubule
Adh and osmolality
Increased osmolality induces adh production
Thirst mechanism and adh mechanism
Are responses to increased osmolality and just water is enough to solve problems since electrolytes are present
What is atrial natriuretic peptide
Cardiac hormone released by right atrium in response ro increased bp
Anp and raas
Anp opposes raas system and suppresses renin aldosterone and adh
Anp stimulayes excretion of
Sodium and water
Anp
Causes vasodilation and decreased vascular resistance
Kinins
Proteins in blood that lowers bp.
Increases sodium and water excretion
Causes inflammation
Dehydration caused by
No water intake
Excessive loss of fluid
Water deficiency condition
Disturbance of body electrolytes
Types of dehydration
Primary
Seconday
Mixed
Primary dehydration
This is due to loss of water.
Causes of primary dehydration
Ill patients who cant eat Mental patients who wont drink Shipwrecked Coma patients Defect to hypothalamus Renal tubular disorder-no reabsorption Diabetes insipidus
Why may bp be normal in primary dehydration
Ecf depletion of water-> drawing of warer from icf-> ecf volume kept fairly constant
PD clinical manifestations?
Dry tongue
Pinched face
Oliguria
Acute nephrotic necrosis
PD Management
Water ro drink
5% iv glucose
Mixed dehydration
Fluid tonicity and volume in both ecf and icf reduced
Most common type of dehydration
Manifestations of mixed type dehydration
Feeling of thirst
Low bp
Oliguria
High blood urea
Md management
Nacl and 5% glucose in 1:1
Secondary dehydration
Occurs when fluids of high nacl are lost.
Ie sweat,gi fluids
Causes of md
Excessive sweating Vomiting ,diarrhea Addisons dx (low aldosterone, na excretion increased) Excessive use of Diuretics Aspiration of gi fluid
Events in secondary dehydration
Loss of electrolyte->Na conc in IF and plasma reduces->decreased osmolarity in if and plasma->water moves into intracellular space->cells swelling-> comvulsions,coma, death.
Aldoaterone function reduced
Sd manifestations
No thirst Patient listless Convulsions Anorexia,nausea Cramps in thigh, abdomen Sunken eyes Inelastic skin Low bp Low gfr
Management
0.9% nacl
Overhydration
Intake or retainment of too much water
Causes of over hydration
Excessive administration of parenteral fluids
Renal failuire(can excrete)
Hypersecretion of adh which can also be caused by anesthesia and narcotics
Excessive aldosterone secretion
Management of over hydration
No drink
Hypertonic saline
Hyponatremia
Na less than 130meq/l
Hypernattrmia
> 145meq/l
Hypokalemia
<3.5meq/l
Hyperkalemia
> 5.1meq/l
Conditions of water imbalance
Edema
Diabetes insipidus
Addisons dx
Cushions dx
Types of di
Central- problem with adh deficiency
Nephrogenic- problem with kidneys or insensitivity to adh
Diagnosis of di
Dilite urine with decreased osmolarity
Decreased specific gravity
Fluid deprivation test( despite deprivation urine volume is constant)
Electrolyte conc in serum amd urine
Treatment of di
Desmopressin
Addisons dx
Defect in adrenal glands which results in low aldosterone $cortisol->increased excretion of water
Biochemical manifestations in addisons
Hyperkalemia
Hypercalcemia
Hypoglycemia
Hyponatremia
Manifestations of addisons dx
Low bp Convulsions Confusion Psychosis Syncope Slurred speech
Diagnosis of addisons
Blood calcium glucose electrolytes Acth stimulating test Cortisol
In acth stimulating test?
Using of synthetic acth hormone- TETRACOSIDE to induce increased cortisol levels. If not,gland is not working
Management of addisons dx
Iv glucocorticoids-Hydrocortisone,Prednisolone
Iv saline wih glucose
Oral doses of fludrocortisone
Cusions syndrome
Overactivity of adrenal glands. Increased aldosterone x cortisol
Biochemical alterations
Hypokalemia
Hypocalcemia
Hyperglycemia
Hypernattemia
Ised for diagnosis
Manifestation of cusions
Depression Moon face High bp Insomnia Weight gain Excessive sweating
Management of cusions
Surgical removal in adrenal adenomas
Drugs-ketoconazole,metyrapone, inhibit cortisol synthesis
Glucocorticoid inhibitor- mifepristone
