Renal System YouTube Lecture Handouts Medical Science

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RENAL SYSTEM

Illustration: RENAL SYSTEM

Functions of Kidney

  • Excretion
    • Metabolic waste
    • Foreign sub-Drugs, etc.
  • Regulation of Fluid & Electrolytes
  • Maintain Acid Base Balance

Functions

Hormonal Functions

  • 1 Renin Angiotensin Aldosterone System
  • 2 Calcitrol
  • 3 Erythropoietin

KIDNEY-ANATOMY

  • Functional anatomy: bean shaped st.
  • Location: retroperitoneal, on post. Abdominal wall. At to Vertebrae
  • Size:
  • Length = 10 cm
  • Width = 5 cm
  • Thickness = 2.5 cm

KIDNEYS

  • Weight of kidney is 150 gm
  • Rt. Kidney slightly lower
  • On medial side a notch, Hilum is present
  • Through it passes
  • Renal artery and veins
  • Lymphatics and nerves
  • Ureter

Renal Sy

  • Microscopic structure
  • Outer-cortex
  • Inner-medulla
  • NEPHRON: structural and functional unit
  • Each kidney has about 1.2 million nephrons
Illustration: Renal Sy

Renal Sy

  • Nephrons are
  • Cortical
  • Juxtamedullary
Illustration: Renal Sy

NEPHRONS

Differences:

Table of Nephrons Differences - 1
Sn

1

2

Feature

No.

Location of glomerulus

Cortical

85%

Small loc. In cortex

JM

15%

Large at corticomedullary junctions

NEPHRONS

Table of Nephrons Differences - 2
Sn

3

4

Feature

LH

LH

lCortical

Short up to outer medulla

Dl thin seg

Al thick

JM

Long

Deep into medulla

Both have thin seg.

NEPHRONS

Differences

Table of Nephrons Differences - 3
Sn

5

6

Feature

Vascular supply

Filtration rate

Cortical

Vasa recta not present

Slow

JM

Vasa recta present

high

NEPHRONS

Differences

Table of Nephrons Differences - 4
Sn

7

Feature

Main function

cortical

Excretion of waste product

JM

Concentration of urine

NEPHRON

  • Structure of nephron: has two parts
  • Renal or Malpighi and corpuscle
  • Tubules
  • Malpighi and corpuscle has:
  • Glomerulus
  • Bowmans capsule
Illustration: NEPHRON

Malpighi and Corpuscle

Glomerulus (tuft of capillaries) –

  • Size – 200 µm
  • Afferent arteriole- short & wide, blood enters through them
  • Efferent arteriole-long & narrow blood leaves, through them
  • Vascular pole- afferent & eff. are close

Malpighi an Corpuscle

Bowman՚s capsule – initial dilated part of nephron. It has:

  • Parietal layer — outer layer
  • Visceral layer — Inner, covering the glomerular capillaries
  • Bowman՚s space — between two layers

Renal System

Diagram

Illustration: Renal System

Glomerular Membrane

Ultrastructure of glomerular membrane

  • Three layers
  • Capillary endothelium: fenestrated pore diameter 70 to 90 nm

Freely permeable to water & solutes

Renal System

2. Basement membrane: matrix of glycoproteins & mucopolysaccharides lamina rara externa lamina dens lamina rara interna has no pores but permeability matches to pore size of about 8 nm

Renal System

3. Visceral epithelium of bowman՚s cap. Formed by podocytes filtration slits diameter — 25 nms slits covered by fine filaments

Renal System

  • Filtration

Membrane

Illustration: Membrane

₹ — Tubules

  • Proximal convoluted tubule
  • Loop of Henle
  • Distal convoluted tubule
  • Collecting tubule
Illustration: ₹ — Tubules
Illustration: ₹ — Tubules

₹ — Tubules

Characteristics of epi. lining tubules:

  • Cells have special features in different seg. & perform specific functions
  • Cells are mostly cuboidal
  • Apical surfaces have microvilli
  • PCT has brush border on luminal side

₹ - JG Apparatus

Also called JG complex: has JG cells macula densa mesangial cells

₹ - JG Apparatus

  • Diagram
Illustration: ₹ - JG Apparatus
Illustration: ₹ - JG Apparatus

₹ – JG Apparatus

  • Juxtamedullary cells:
  • Modified my epithelial cells
  • Located in the media of aff. Arteriole
  • Granular cells
  • Densely innervated by sympathetic
  • Secret RENIN
  • Baroreceptor by function

₹ — JG Apparatus

Macula Densa Cells:

  • Are in contact with mesangial & JG cells
  • Not well adapted for reabsorption
  • Not innervated
  • Act as chemoreceptor
  • Stimulated by ↓ Nacl
  • ↓ Renin release

₹ -JG Apparatus

  • Mesangial cells or Lacis cells
  • Possibly relay signals from macula densa to granular cells
  • Take up immune complexes
  • In extreme hyperactivity show granules containing renin

JG-Apparatus

Functions:

  • Renin secretion
  • Regulation of GFR
  • Mesangial cells mediate signals between Macula Densa & Afferent Arteriole
  • Mesangial cells within the glomerulus communicate with cells outside
  • ↓ surface Area of filtration when BP is V. low

₹ -Renal Blood Flow

  • Renal circulation is portal circulation 2 sets of capillaries are present
  • Amount & rate of flow
  • In basal condt … 1200 ml⟋min.
  • High flow is related to excretory function.
  • Flow is remarkably constant due to Autoregulation

₹ -Renal Blood Flow

Internal distribution of blood flow

  • Cortex … 90%
  • Outer medulla … 9%
  • Inner medulla … 1%
  • Low blood flow through medulla helps in urinary concentration.
Illustration: ₹ -Renal Blood Flow
Illustration: ₹ -Renal Blood Flow

₹ — Renal Blood Flow

Autoregulation of renal blood flow

  • Feature of cortical blood flow
  • Present in denervated kidney
  • Seen in transplanted kidney.

₹ — Renal Blood Flow

Autoregulation of renal blood flow:

  • Myogenic Theory
  • Tubuloglomerular feedback
  • Cell separation Theory
  • Intrarenal tissue pressure
  • Intrarenal reflexes

₹ — Renal Blood Flow

Measurement, 2 methods

  • Venous shunt technique
  • Fick principle

Fick principle: substance used

  • Con. In blood can be measured easily
  • Not metabolized, stored or produced
  • Does not affect blood flow

₹ — Renal Blood Flow

  • Substances used are
  • PAH (p-amminohippuric acid)
  • Diodrast
  • Usually PAH is used, it has high extraction ratio 90%

₹ — RBF

  • Effective Renal plasma flow:
  • ERPF = UPAHxV⟋PPAH = clearance of PAH e. g. = UPAH = 14 mg⟋ml V = 0.9 ml⟋min PPAH = 0.02 mg⟋ml
  • ERPF .

₹ — RBF

  • ERPF is converted to actual plasma flow Extraction ratio is 0.9

Actual Plasma flow = 630⟋0.9 = 700 ml⟋min

  • Hematocrit = 45%
  • RBF = RPF
  • RBF ml⟋min or 1.2 L⟋min

₹ — Urine Formation

  • Mechanism: includes
  • Filtration … (glomerulus)
  • Reabsorption … (tubules)
  • Secretion … (tubules)
Illustration: ₹ — Urine Formation

₹ — Glomerular Filtration

  • Definition: Amount of fluid filtered by all the nephrons of both the kidneys⟋min.
  • Normal value ml⟋min.
  • Filtration fraction: Ratio of GFR to renal plasma flow

Filtration Fraction

Is

  • FF = GFR (ml⟋min.) , RBF (ml⟋min) Normal range %

Dynamics of Filtration

NET FILTRATION PRESSURE

Forces Favoring Filtration

1. Gl. Hydro. Press. = 60 mmHg

2. Colloid osmotic pressure of Bowman՚s capsule = 0

GFR

Forces Opposing Filtration (mm Hg)

1. Capsule Hydrostatic Press. = 18

2. Gl. Cap. Colloid osmotic Pressure = 32

  • NET FILTRATION PRESSURE:

60 - (18 + 32) =+ 10 mm Hg

GFR

Filtration Coefficient:

  • Rate of filtration⟋mm Hg Filtration Press
  • ml⟋min⟋mm Hg
  • It is GFR at 1 mm Hg Effective Filtration Pressure
  • It is product of permeability and filtration area

Filtration Membrane

  • Permeability-
  • Pores in capillary Endo. Cell -70 - 90 nm
  • Podocytes Filtration Slits … 25 nm
  • Glomerular Basement Mem. Has no pores but permeability corresponds to pore size of 8 nm.
Illustration: Filtration Membrane

Filtration Membrane

  • Molecules less than 4 nm — freely filtered
  • Molecules more than 8 nm-not filtered
  • Pores are – vely charged due to presence of glycoproteins rich in sialic acid
  • Albumin with mol. Diameter of 7 nm is negatively charged so not filtered
Illustration: Filtration Membrane

Filtration Membrane

  • Area
  • Controlled by mesangial cells
  • COMPOSITION OF FILTRATE:
  • Like plasma except for absence of proteins and cells

Factors Affecting GFR

  • Glomerular capillary hydrostatic press.
  • Glomerular capillary oncotic pressure
  • Hydrostatic press. of fluid in Bow. Cap.
  • Filtration Coefficient
  • Permeability of membrane
  • Filtration Area

GFR Measurement

  • By Clearance method:
  • Salient features of the substance used
  • Not toxic & biologically inert
  • Is freely filtered
  • Has no effect on GFR
  • Not absorbed or secreted by tubules
  • Not stored in kidneys

GFR Measurement

Substances used:

  • Inulin- A polysaccharide Mol. Wt. 5200
  • Creatinine
  • Sodium Ferro cyanides
  • Mannitol
  • Radioactive cobalt labelled vit. B12
  • R. A. 51 Cr. labelled EDTA

GFR- Inulin Clearance

  • C in
  • Uin mg⟋ml
  • V ml⟋min
  • Pin mg⟋ml
  • ml⟋min is GFR

Creatinine Clearance

  • Endogenous Creatinine Clearance is easy to measure
  • Some reabsorbed & some secreted in tubules
  • Not very exact but convenient

Tubular Reabsorption

  • Filtered Load: Amount of solute transported across the glomerular membrane per unit time.
  • Filtered load = GFR x Plasma concentre of the solute

Glomerulotubular Balance

  • Is percentage of filtered fluid that is reabsorbed in proximal tubule?
  • It is constant i.e.. 70% of fluid filtered.
  • Key element in PT reabsorption is Na +- K +- ATPase

Substances Reabsorbed in PT

Important substances reabs. are

  • Sodium
  • Glucose
  • Aminoacids
  • Bicarbonates

Reabs of Sodium

~65% of filtered sodium is reabsorbed

  • In first half by co-transpot along with glucose, aminoacids etc.
  • In second half with chloride
Illustration: Reabs of Sodium

Glucose Reabsorption

  • Essentially all is reabsorbed only few mg. appear in urine
  • Secondary Active transport
  • Filtered at a rate of about 100 mg⟋min.
  • (Plasma concentration … 80 mg⟋dL & GFR … 125 ml⟋min)

Renal Threshold & Tm

Renal Threshold:

  • Plasma glucose level at which it first appears in urine … 180 mg⟋dL
  • Transport Maximum is max. Rate at which a substance is transported. Limiting factor is saturation of carrier proteins

TMG

Transport Maximum of Glucose

  • Males … 375 mg⟋min Corresponding Plasma Level 300 mg⟋dL
  • Females — 300 mg⟋min (Tm and Value)
  • Amino acids 1.5 mg⟋min
  • Plasma proteins 30 mg⟋min

Bicarbonate Reabsorption

Illustration: Bicarbonate Reabsorption

Reabsoption of WATER

  • Total fluid filtered … 180 L⟋day
  • Urine output … 1 L⟋day

Reabsoption is by Two Ways

  • Obligatory water Reabsoption &
  • Facultative Reabsoption.

Obligatory Reabsoption

  • In proximal tubules
  • Secondary to solute reabs.
  • Osmotic reabs.
  • About 65%
  • Cannot be changed according to need of body

Facultative Water Reabsorb

  • In distal tubule & collecting tubule
  • It changes according to need of body
  • Controlled by ADH

Water Reabs. In Different Parts

  • Approx. values are
  • PT … 60 to 70%
  • LH … 15%
  • DT … 5%
  • CD … C … 10
  • … M … 4.7%

Mechanism of Water Reabs

  • By diffusion across cell membrane
  • Diffusion is through protein channels called AQUAPORIN
  • Different types of Aquaporins are in human beings: 1, 2,3, 4,5 &9
  • Aquaporin 1&2 play key role in water reabs
Illustration: Mechanism of Water Reabs

Mechanism of Water Reabs

  • Aquaporin-1 is localized in proximal tubules
  • Aquaporin-2 is in collecting ducts
  • Stored in the vesicles in the cytoplasm of Principal Cells
  • Vasopressin causes insertion of these vesicles into the apical mem. of cells

Mechanism of Water Reabs

  • Effect mediated by receptors
  • Cyclic AMP, Protein kinase & a molecular motor (one of dyneins) are also involved

Regulation of Urine Osmolarity and Volume

Body can produce

  • Vol. of urine⟋day Osmolarity mOsm⟋L
  • 500 ml … 1400
  • 23.3 L … 30
  • About 87% of filtered Water is always reabs.

Osmolarity

  • Human … 1400 mOsm⟋kg of water
  • Dogs … 2500
  • Rats … 3200
  • Some … 5000

Rodents

It depends on max. Osmolarity present in medulla

Mechanism of Concentration & Dilution of Urine

Principal factors:

  • ANTIDIURETIC HORMONE
  • GRADIENT OF OSMOLARITY IN RENAL MEDULLA
  • SLUGGISH BLOOD FLOW IN MEDULLA

ANTIDIURETIC HORMONE

  • ADH is required for water reabsorption
  • Maximum ADH … 99% reabsorbed
  • Absence of ADH … 88%

Gradient of Osmolarity in Renal Medulla

  • Gradient generated by Counter Current Multiplier system
  • Maintained by C. C. Exchange system
Illustration: Gradient of Osmolarity in Renal Medulla

Counter Current Multiplier System

Illustration: Counter Current Multiplier System

Counter Current Multiplier System

  • In flow runs parallel to, counter to and in close proximity to outflow.
  • It is active process
  • It generates gradient of osmolarity in renal medulla
  • Key role is played by LOOP of HENLE

LOOP of HENLE

  • DLH is CONCENTRATING SEGMENT
  • Highly permeable to water
  • Relatively impermeable to solutes. Therefore
  • Solute free water moves in interstitium
  • Fluid in DLH becomes concentrated

LOOP of HENLE

  • ALH is DILUTING SEGMENT
  • Thin seg. Impermeable to water & permeable to NaCl and urea
  • Thick seg.
  • Impermeable to water & solutes
  • ACTIVE TRANSPORT of NaCl out of lumen

LOOP of HENLE

  • Sodium transported by
  • Na +-K +-ATPase and
  • In ALH tubular fluid becomes more & more dilute & rich in urea
  • Interstitial fluid becomes hyperosmotic
  • MEDULLARY HYPEROSMOLARITY Gen.

COUNTER CURRENT EXCHANGE SYSTEM

  • Formed by VASA RECTA
  • Cannot generate gradient
  • But maintain gradient of osmolarity in medulla
  • Passive mechanism

CCM

Illustration: CCM

CC Exchange

  • Solutes tend to recirculate in medulla
  • Water tends to bypass it.
  • Medullary HYPEROSMOLARITY is MAINTAINED

Sluggish Blood Flow in Renal Medulla

  • Blood flow of Cortex … 90%
  • Flow of Outer Medulla … 9%
  • Flow of Inner Medulla … 1%

Role of Urea in Concern of Urine

  • DCT & CT- Impermeable to water
  • Urea concern Increases in CT
  • IMCD- Permeable to urea so both water & urea are absorbed in here
  • Outer Medullary interstitial Osmolarity is because of sodium
  • Inner medullary by both Na + & urea
Illustration: Role of Urea in Concern of Urine
Illustration: Role of Urea in Concern of Urine

Formation of Concern Urine

↑ Osmolarity of extracellular fluid

↑ Release of ADH from post. Pituitary

↑ Permeability of DCT & Collecting duct

↑ Increase water reabs.

Formation of Dilute Urine

  • ↓ Osmolarity of ECF (excess of water) ↓
  • ↓ ADH secretion ↓
  • ↓ Permeability f DCT & collecting duct ↓
  • Less water is reabsorbed

Water Diuresis

  • If large amount of water is taken. Within 45 min. urine output increases. Due to decreased ADH. It continues until osmolarity comes back to normal.

Acidification of Urine

  • pH is negative log of H ion concentration.
  • pH of solutions
Illustration: Acidification of Urine

Normal pH

  • Plasma pH- 7.4
  • Urine pH … 6.0
Illustration: Normal pH

Secretion of H Ions

  • There is always an excess of H ions in body & they must be excreted
  • Hydrogen ions are secreted from tubules

H Ion Secretion in PT

  • In PT secretion depends on sodium reab.
  • It is by Secondary Active Transport Na +-H + antiport
  • For secretion of every hydrogen ion one Sodium & one Bicarbonate ions are reabsorbed

H Ion Secretion in DT

  • Independent of sodium reab.
  • Mainly by ATP driven PROTON PUMP
  • Aldosterone acts on this pump
  • Active reab.

III

Illustration: III

H ION Secretion

  • PCT (rich in CA) … 85%
  • DCT … 10%
  • Collecting tubule … 5%

Fate of H IONS Secreted

  • LIMITING pH of urine is 4.5 so H IONS must be buffered in tubule
  • BUFFER SYSTEMS IN THE KIDNEY
  • Bicarbonate system
  • Dibasic Phosphate system
  • Ammonia system

Bicarbonate Buffer

  • In PCT
  • No change in tubular fluid pH
  • Large amount of H ions are secreted here
  • H Ions buffered do not add to urinary acidity
Illustration: Bicarbonate Buffer

Dibasic Phosphate Buffer

  • More important in DCT, as phosphates are concentrated here
  • Dibasic phosphate ions are converted to monobasic phosphate
  • to
  • It adds to urinary acidity

II

Illustration: II

Ammonia Buffer

  • Ammonia is synthesized & secreted by DCT&CT
  • Sources of Ammonia are
    • 60% by deamination of Glutamine
    • 30% by deamination of Glutamic acid
    • 10% by deamination of other aminoacids like Glycine, Alanine etc.

Ammonia Buffer

  • Important points
    • Ammonium ion major urine acid
    • Ammonium content increases when urine pH is below 6
    • There is adaptative increase in Ammonia synthesis. In Diabetic ketosis H ion excretion may increase 10 folds.

TITRABLE ACIDITY

  • Definition: Amount of Alkali that must be added to the urine, so as to bring its pH to 7.4
    • H buffered by Bicarbonate not measured
    • Large contribution is by Phosphate buffers
    • It does not measure H ions that combine with Ammonia

Urinary Acid Excretion

  • Urinary acid Normal Excretion in mEQ or mmol⟋day
    • Titrable Acid (25%) … 10 - 30
    • Ammonium ion (75%) … 30 - 50
    • Total … 40 - 80

PHYSIOLOGY of MICTURITION

  • Includes
  • Structure & Innervation of bladder
  • Physiology of micturition
    • Filling of bladder
    • Micturition Reflex
  • Abnormalities of micturition

Structure of Urinary Bladder

Has

  • Body of urinary bladder
  • Urethra &
  • Sphincters
  • Internal sphincter (smooth muscles)
  • External sphincter (skeletal muscle)
Illustration: Structure of Urinary Bladder

Urinary Bladder

  • Capacity:
    • At birth … 20 - 50 ml
    • At one year … 200 ml
    • In adult … 600 ml

INNERVATION

Is by

  • Sympathetic nervous System
  • Parasympathetic &
  • Somatic nervous system

Motor Innervation

  • Symp. Is from 2&3
  • Effect of stimulation
    • They relax Detrusor muscles
    • Contraction of Int. Sphincter
    • Retention of urine
    • Prevent reflux of sperms from prostatic urethra to urinary bladder during ejaculation

Motor INNERVATION

  • Parasymp. (Nervi erigentes) :
  • From S 2,3 & 4
  • Effect of stimulation
    • Contraction of Detrusor muscle
    • Relaxation of Internal sphincter
    • Leads to emptying of bladder
  • Somatic innervation: S 2,3 & 4 (Pudendal Nerve) to Ext. Sphincter

Sensory Inn

  • For
  • Bladder distension &
  • Bladder pain

SENSORY Innervation

  • Bladder distension:
    • From Detrusor mus. Pelvic Splanchnic Nerves
    • From bladder Neck & Trigone via Hypo gastric plexus
    • Fibres travel in Post. column to reach spinal, pontine& supra pontine M. C.

SENSORY Innervation

  • Bladder pain:
  • In Hypogastric plexus
  • Some in nervi erigentes
  • Run in Lateral Spin thalamic Tract Urethral sensation: Pudendal nerve

Bladder Filling

  • Urine flows from Renal pelvis towards bladder by peristaltic cont. of ureters
  • Renal calyces have inherent Pacemaker activity
  • Peristaltic cont. enhanced by Parasymp.
  • Inhibited by Sympathetic

Cystometry

  • Cystometrogram
  • Shows changes in intravesicular pressure as the bladder fills with urine
  • First urge to pass urine … 150 ml
  • Marked fullness & discomfort … 400 ml
  • Unbearable … 600 ml
  • Anatomical capacity … about .

Micturition Reflex

  • Fundamentally a spinal reflex, facilitated & inhibited by higher centres
  • It is a Parasympthetic Reflex
  • Higher Control:
    • Faci. — Post. Hypothalamus & Pontine reg.
    • Inhi. — mid brain
    • Cerebral cortex — in voluntary micturation
Illustration: Micturition Reflex

Spinal Mic. Reflex

  • Filling of bladder (Afferent nerves) ↓
  • Sacral segment of spinal cord (Mic. Cen) ↓
  • Efferent to motor nerves ↓
  • Emptying of bladder

VOL. MICTURITION

  • Impulses reach to S 234 ↓
  • Dorsal column (travel upwards) ↓
  • Brain (Post Central Gyrus) ↓
  • Motor Cortex ↓
  • Sacral Seg. (Emptying of bladder)

Desire to Hold Urine

  • Cerebral Cortex ↓
  • 1 Inhibit Sacral Parasy. Excitatory activity
  • 2 Stimulate Symp. Activity ↓
  • Desire to Micturate PASSES OFF
  • Only a temporary phase

Accessory Muscles Involved

Muscles Involved during Micturition:

  • Abdominal muscles Contract
  • Perineal muscles Relax
  • Diaphragm descends
  • Breathing is hold with glottis closed
  • Thus Intra-Abdominal Pressure ↑

Applied Aspects

  • DEAFFERENTATION
  • DENERVATION
  • TRANSECTION OF SPINAL CORD

DEAFFERENTATION of URINARY BLADDER

  • Cause: Tabes Dorsalis (Syphlis)
  • Findings:
    • Vol. mict. Is possible
    • Unaware of state of bladder distension
    • Periodical emptying not present
    • Overflow dribbling – AUTOMATIC BLADDER
    • DISTENDED, THIN, HYPOTONIC BLADDER

DENERVATED BLADDER

  • Cause: Tumour or injury to Cauda Equina. Injury to both Afferent & Efferent nerv.
  • Loss of vol. Micturition
  • Bladder is flaccid and distended for a while
  • Bladder is decentralized
  • SHRUNKEN HYPERTROPHIED BLADDER

TRANSECTION of SPINAL CORD

Cause: injury, Syringomyelia, Disseminated Sclerosis

  • Both facilitatory and Inhibitory fibres are damaged
  • Recovery in two stages
    • Early Stage (stage of spinal shock)
    • Late stage

SPINAL TRANSECTION

EARLY STAGE:

  • Vol. Mict. Abolished
  • State of retention with overflow develops
  • Bladder becomes spastic neurogenic
  • Complications like cystitis and ascending urinary tract infections can develop

SPINAL TRANSECTION

LATE STAGE:

  • Voiding reflex returns
  • No voluntary control
  • Micturition can be initiated by mass reflex

Endocrinal Functions

  • Erythropoietin
  • Calcitrol
  • Renin a Proteolytic Enzyme

HORMONES ACTING on KIDNEY

  • Aldosterone
  • Antidiuretic hormone
  • Parathormone
Illustration: HORMONES ACTING on KIDNEY

Renal Function Tests

  • Performed to
  • Asses the functional capacity of the kidney
  • To detect the renal impairment in the early stage

Renal Function Tests

Various tests are performed

  • Analysis of urine
  • Analysis of blood
  • Renal Clearance tests
  • Radiology & Renal Imaging
  • Renal Biopsy
  • Other methods

Urine Analysis

Normal Colour … light yellow due to

  • Pigments -Urochrome, urobilin &Uroerythrin
  • Deepens on standing, oxidation of urobilinogen to urobilin
  • Brownish yellow … presence of conjugated Bilirubin
  • Red- Dark brown … porphyria
  • Frothy in Proteinuria

Urine Analysis

Composition

  • Inorganic … Na, K, Ca & phosphate
  • Organic …
  • Urea … 20 to 30 g⟋day
  • Uric Acid … 0.6 gm⟋day
  • Creatinine … 1.2 gm⟋day

Urine Analysis

  • Normal vol. = Approx. 1 to 2.5 L⟋day
  • Polyuria = 2.5 L⟋day (fluid intake not high)
  • Oliguria = 500 ml⟋day
  • Anuria < 50 ml⟋day or no urine formed
  • Obligatory urine vol. = 500 ml⟋day.
  • It is minimum quantity of urine that must be formed to remove waste products.

Urine Analysis

Osmolality & Specific gravity

  • Normal Osmolality = 50 to 1200
  • Normal Specific Gravity = 1.003 to 1.030
  • Fixed Osmolarity of 300 mOsm⟋Kg (sp. gr. -1.010) = Advanced renal failure
  • Persistently low Osmolality less than 100 (after 8 hr. fluid deprivation) diagnostic of Diabetes Insipidus

Urine Analysis

Approx. correlation between S. G. and osmolality

Table of Urine Analysis
S. G.Osmolality (mOsm⟋kg)
1001100
1010300
10251000
10301200
10401400

Urine Analysis

Reaction

  • Normal range … 4.5 to 8, Av. 6 - 7
  • After meals it becomes alkaline (postprandial alkaline tide)
  • Alkaline urine turns red litmus blue

Urine Ana

  • Microscopic
  • normally
    • 1 to 2 WBC or Pus Cells⟋HPF
    • Hyaline Cast = occasional
    • They are clear, colourless cast made up of high molecular weight mucoproteins

Urine Analysis

Abnormal constituents

  • RBC
  • Bacteria
  • Granular casts
  • Glucose
  • Albumin
  • Ketone bodies

Applied

  • Isosthenuria … S. G. of urine is fixed at 1010 (Pl. 300 mOsm⟋L e. g Renal Failure)
  • 12 hours water deprivation ↑ S. G. to 1025 failure to do this indicates abnormal Renal functions
  • Albuminuria – Albumin excretion above 150 mg⟋day

Albuminuria

Causes

  • Nephritis
  • TB
  • Carcinoma

Albuminuria

Orthostatic Albuminuria

  • Albumin appears in urine in standing position

Blood Analysis

Normal

  • Blood Urea … 20 to 40 mg %
  • S. Creatinine … 0.6 to 1.5 mg %
  • S. Cholesterol … 150 to 240 mg %
  • Uric Acid … 2 to 4 mg %
  • Protein A⟋G ratio 1.7: 1
  • Nephrotic Syndrome reversal of A⟋G ratio

Clearance Tests

  • Tests for Glomerular Functions
    • Inulin Clearance
    • Creatinine Cl.
  • Tests for Tubular Functions
    • PAH Clearance
    • Urea Clearance
    • Phenol Sulphonephthalein (PSP) test

Urea Clearance

  • Standard Urea Cl. - urine flow 2 ml⟋min normally … 54 ml⟋min (40 to 60)
  • Maximum Urea Cl. … flow 2 ml⟋min normally … 75 ml⟋min (60 to 90)
  • It is obsolete & not used clinically

Other Methods

  • Micropuncturing
  • Stop Flow Tech.
  • Microcryoscopic studies

Diuretics

  • Are substances that cause increase in urinary flow
  • They are of various types
Table of Diuretics - 1
123456
Class of DiureticSite of act.Mechanism of actionEffectK+ depletionpH
HIGH EFF. LOOP DIURETICSTALInhibition of pump↑NaCl excret.

excret

YesAlkal.
Table of Diuretics - 2
123456
MEDIUM EFFICACY THIAZIDE DIURETICS

Chlorthiazide

Hydrochlorthiazide

Early DTInhibition of symporterExc of

Antihypertensive

YesAlkal
Table of Diuretics - 3
123456
WEAK DIURETICS

1. C. A. INHIBITORS

Acetazolamide

2. Sparing

Spironolactone

Triamterene

Amiloride

PT

Late DT &CD

Inhibition of Carbonic Anhydrase

Inhibition of Na+ Reabsor & Inhibition of K+ Exc.

HCO- 3 Excretion

Excret &

K+ Excretio

Yes

No

Acidosis

Acidosis