URINE Urine Physical properties

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URINEUrine Physical properties
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• The kidney is an organ which does not simply
  remove the metabolic waste products, but actually
  performs an important homeostatic function.

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• It regulates
• the internal environment
• of the body cells by
• 3 mechanisms

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• 1) Glomerular filtration.
• 2) Selective tubular reabsorption of substances
  that are necessary to maintain the internal
  environment and
• 3) Tubular secretion of substances from the blood
  into the tubular lumen for excretion into the
  urine.
• These 3 mechanisms result in
• urine formation.

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PHYSICAL PROPERTIESOFURINE
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• 7 ITEMS
• Volume
• Colour
• Aspect
• Deposits
• Odour
• Reaction
• Specific Gravity

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• Volume
• It ranges between 1 and 1.5 L/day.
• The volume depends on
• water intake,
• external temperature,
• diet,
• mental and physical state of the individual.

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Volume
more than 2 L/day

• Physiological increase
• In winter
• After excessive fluid intake- Coffee
• Nervousness or excitement

N.B. Normally, more urine is excreted during
the day than at night.
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• Abnormal increase (polyuria )
• More than 3 L/day
• diabetes mellitus (may reach 5 L/day)
• diabetes insipidus (10-15 L/day)
• hyperparathyroidism.
• Hypercalcemia ? -- Action of ADH

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Volume

• Physiological decrease
• in summer due to increased sweating
• during fasting or restricted fluids in diet.

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Volume

• Abnormal decrease (Oliguria)
• Less than 200 ml/day
• acute nephritis,
• heart failure,
• shock, burns
• haemorrhage.
• vomiting and diarrhoea.

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Volume

• Anuria
• No urine at all (or lt 50 ml /day)
• late stages of renal failure
• and heart failure.

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• Colour
• Normal colour is amber yellow.
• due to pigments called urochromes , urobilin or
  urobilinogen peptide.
• There are also other pigments (coproporphyrin,
  uroerythrin), but occur in small amounts.

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• The colour is changed
• in the following conditions

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• Diabetes insipidus colourless or pale yellow.
• Fever, deep orange.
• Obstructive jaundice Greenish brown due to
  presence of cholebilirubin.
• Haemorrhage in urinary tract, reddish brown
  colour.
• Alkaptonuria Black (homogentisic acid is
  oxidized to give black colour when exposed to air.

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• Ingestion of
• food coloured with dyes or
• coloured drugs result in discolouration of urine.

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• Odour
• Fresh urine is normally aromatic (urineferous).
• This odour is changed by
• Different types of food Cabbage, garlic, onion.
• Severe uncontrolled diabetes mellitus Fruity
  odour due to presence of acetone/acetoacetoacetic
  acid.
• Contaminated urine Ammoniacal odour. In stagnant
  urine, this odour is due to bacterial action,
  e.g. on urea which is converted into ammonia.
• Putrefaction Putrid odour due to bacterial
  growth in urinary infection.

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Normally aromatic (urineferous)
Odour
Fruity odour
Severe uncontrolled DM
Ammoniacal odour
Putrid odour
Growth
Urease
Bacteria
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• Reaction
• On mixed diet, it is acidic (pH is 6). It may be
  slightly acidic or slightly alkaline.
• The urine pH depends on
• the ratio of acid phosphate (NaH2PO4) to alkaline
  phosphate (Na2HPO4). The kidney mainly excretes
  acid phosphate to preserve the alkali.

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• Reaction
• High protein diet gives acidic urine
• due to excretion of excess phosphate and
  sulphate.

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Reaction

• Vegetables and fruits give alkaline urine
• due to their high sodium and potassium content
  with excretion of sodium and potassium
  bicarbonate in urine

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Reaction

• Alkaline urine
• is passed
• an hour after a meal,
• this is the so called
• alkaline tide.

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• Aspect
• Normal urine is clear (transparent).
• On standing, it turns cloudy due to precipitation
  of muco- and nucleoproteins and epithelial cells
  (present in traces in normal urine).

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• It becomes turbid and opaque due to presence of
  albumin.
• Exposed urine is a good medium for bacterial
  growth as its pH becomes alkaline, resulting in
  precipitation of phosphates.

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• Deposits
• Normal urine is
• devoid from deposits.
• In case of its presence, it depends on the colour
  and shape of deposit.
• In order to examine the deposit, we make
  centrifugation to urine then microscopic
  examination.

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• a) Crystals urates and oxalates (acid
  urine),
• tripple phosphate (ammonium magnesium phosphate
  NH2MgPO4) (alkaline urine)
• b) Casts albuminoid substances released from
  epithelial
• c) Parasitic ova and
• d) Cells Pus cells or RBCs.

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Microscopic examination of the solid parts of
urine the picture shows red blood cells (above),
white blood cells (middle) and a cast of
clumped-together white blood cells (below).
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• A urinary cast is a protein or cellular debris,
  that forms within a renal tubule.
• The material or cells that form a cast may have 
• come through a damaged glomerulus, 
• been part of an interstitial inflammatory
  infiltrate, 
• have been dead tubular cells.
• The cast is expelled into the urine, and
  maintains the shape of the tubule in which it
  formed.
• Casts reflect conditions of the kidney proper and
  not the lower urinary tract.
• In most cases they are significant and must be
  explained.

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• Specific gravity
• Normally, it ranges between 1.015 to
  1.025
• It varies inversely with the volume of urine,
  e.g. ? In diabetes insipidus, it is low (1.004).
• In fever, it is high (more than 1.030) due to
  small amount of urine.
• In diabetes mellitus, the specific gravity is
  1.40 due to the presence of glucose.

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• A diseased kidney loses its ability to dilute or
  concentrate urine

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Water diuresis test

• Evacuate The Bladder
• Then, Drink 1.5 L of water.
• Urine will be collected every half an hour for 5
  hours
• For each sample, ? determine volume specific
  Gravity.
• Normally, after 5 hours, ? shold void at least
  800 ml Sp. Gravity lt 1.010
• If the distal tubules function is impaired ?
  Diuresis doesnot occur Sp. Gravity doesnot drop
  below 1.010

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Water Concentration test

• Evacuate The Bladder
• Then, No Drinking for 10-12 hours to produce
  dehydration.
• At the end of the 12 hours Urine will be
  collected
• determine volume specific Gravity.
• Normally, Sp. Gravity shold rise to 1.025
• If with dehydration, the Sp. Gravity remains
  below 1.020 ? it indicates that the function of
  Loop of Henle distal Tubules is inhibited