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Sections of the Laboratory. CLINICAL PATHOLOGY 1. Clinical Chemistry BUN Cholesterol FBS 2. Clinical  Microscopy Analysis of body fluids Urin analysis Fecal anaysis Semen analysis. 3. Microbiology Cultures (sputum, blood, urine) 4. Hematology Biggest section 

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sections of the laboratory
Sections of the Laboratory


1. Clinical Chemistry

  • BUN
  • Cholesterol
  • FBS

2. Clinical Microscopy

  • Analysis of body fluids
  • Urin analysis
  • Fecal anaysis
  • Semen analysis

3. Microbiology

  • Cultures (sputum,

blood, urine)

4. Hematology

Biggest section 

Includes CBC,coagulation, PT, PTT 

blood bank
Blood bank

Very critical section

Bec. May have errors

  • Blood typing
  • Cross match
  • AB
  • Identification

Goes hand in hand with serology and immunology

Tests done for

  • HIV


  • Cardiac and thyroid fxntest



Submission of tissues for tests

nature of request
Nature of Request


  • Performed immediately and by itself. 
  • Run control and standard
  • 20-50% More expensive
  • TAT is shortened
  • Request is needed


  • Confusing
  • Performed as soon as possible, given priority
  • Based on “running time”


  • Done with the batch
  • Wait for TAT stated by laboratory


  • Better term than “normal value”
  • Pulled value, usually 95%of population
  • Vary in diff. hospitals but not that far


  • Clinical decision should be made if higher or lower than reference value
  • Usually when 2x to 3x
critical values
  • Needs immediate attention
  • “panic values”
  • Should call physician
  • Patient is at risk
reference values
Reference Values

Not fixed for all

Should consider:

  • Age
  • Sex
  • Pregnancy
  • Diurnal Variation
  • Race
  • Blood type
routine examinations
Routine Examinations


CBC, Urinalysis, Fecalysis


BUN, Creatinine, Glucose, Uric Acid, Cholesterol

Sometimes triglycerides

basic lab equipments
Basic lab equipments
  • The Light Microscope.
  • Colorimeters and photometers
  • Water bath
  • Laboratory centrifuge
  • Balance
  • Cold incubators refrigerators
  • pH meters
  • Mixers
  • Ovens
  • De-ionizers
  • Safety cabinets.
  • Glassware and plasticware
  • Pathologist should try to answer the question which is imposed by the clinician.
  • Correct specimen for requested test with necessary information so that right test is carried out And result is delivered to the requesting clinician with the minimum of delay.
  • Patient identification must be correct.
specimen types
Specimen types
  • Venous blood serum or plasma.
  • Arterial blood.
  • Capillary blood
  • Urine
  • Feces
  • Cerebrospinal fluid
  • Sputum and sliva
  • Tissue and cells
  • Aspirates (pleural fluid, ascites, joint fluid, intestinal (duodenal) fluid, pancreatic pseudocysts.
  • Calculi
blood specimens
Blood specimens
  • Serum
  • Plasma

Urine specimen

  • Preservative may be added to prevent bacterial growth or acid may be added to stabilize metabolites.

Other specimen types

Dangerous specimen

  • Labelled as “dangerous specimen” yellow sticker.
  • Similar label should be attached on the request form.
  • HBV and HIV
sampling errors
Sampling errors
  • Blood sampling techniques
  • Prolonged stasis during venepuncture
  • Insufficient specimen
  • Errors in timing
  • Incorrect specimen container
  • In appropriate sampling site
  • Incorrect sample storage.
lipid chemistry and cardiovascular profile
Lipid chemistry and cardiovascular profile
  • Main lipids in the blood are the triglycerides and cholesterol.(phospholipids, FFA)
  • These are insoluble in the water.
  • Transport in the blood is via lipoproteins.(protein)
  • 4 major classes of lipoproteins.
    • Chylomicrons
    • Very low density lipoproteins (VLDL)
    • Low density lipoproteins (LDL)
    • High density lipoproteins (HDL)
  • Chylomicrons carry triglycerides ( dietary fat) from the intestines to the liver, to skeletal muscle, and to adipose tissue.
  • Very-low-density lipoproteins (VLDL) carry (newly synthesised or endogenous) triglycerides from the liver to adipose tissue and metabolized to LDL through IDL.
  • Intermediate-density lipoproteins (IDL) are intermediate between VLDL and LDL. They are not usually detectable in the blood.
  • Low-density lipoproteins (LDL) carry cholesterol from the liver to cells of the body. LDLs are sometimes referred to as the "bad cholesterol" lipoprotein.
  • High-density lipoproteins (HDL) collect cholesterol from the body's tissues, and take it back to the liver. HDLs are sometimes referred to as the "good cholesterol" lipoprotein.

60% of plasma cholesterol is present in LDL, 25% in HDL and small quantity in VLDL.

  • Lipoprotein metabolism is controlled by their protein component apolipoproteins.
  • Apo A-1 in HDL and Apo B-100 in LDL are very important ones.
  • Lipoprotein (a) in also present in human plasma. It is synthesized in the liver.
  • Smaller but denser than LDL.
  • Cholesterol esters are major lipids and it is an independent risk factor for IHD.

LDL and VLDL are associated with premature atherosclerosis.

  • HDL high levels are negative risk factors for IHD.
  • Coronary heart disease
  • Acute pancreatitis
  • Failure to thrive and weakness
  • Cataract

Endothelial dysfunction

  • Lpid accumulation.
  • Migration of inflammatory cells into the arterial wall.

Atherosclerosis and plaque formation

Plaque stability

SCAD (asymptomatic)

Chest pain at rest

(angina, non ST elevation MI, STEMI)

  • Atherosclerotic plaque, rupture and thrombus formation.
  • Obstruction of coronary circulation.
  • Necrosis of the heart tissue.
  • Irreversible cardiac injury if occlusion is complete for 15-20 mins.
  • Starts from endocardium and spreads towards epicardium.
  • If full thickness of myocardium is involved then it is transmural infarct.
diagnosis of mi
Diagnosis of MI
  • Detection of rise and fall of cardiac biomarker troponinT/I with one of the following:
  • Symptoms of ischemia
  • ECG changes
  • Q wave
lactate dehydrogenase ldh
  • Catalyzes the reversible oxidation of lactate to pyruvate
  • Used to indicate AMI
  • Is a cytoplasmic enzyme found in most cells of the body, including the heart
  • Not specific for the diagnosis of cardiac disease
distribution of ld isoenzymes
Distribution of LD isoenzymes
  • LD1 and LD2 (HHHH, HHHM)
    • Fast moving fractions and are heat-stable
    • Found mostly in the myocardium and erythrocytes
    • Also found in the renal cortex
  • LD3 (HHMM)
    • Found in a number of tissues, predominantly in the white blood cells and brain
  • LD4 and LD5 (HMMM, MMMM)
    • Slow moving and are heat labile
    • Found mostly in the liver and skeletal muscle
considerations in ld assays
Considerations in LD assays
  • Red cells contain 150 times more LDH than serum, therefore hemolysis must be avoided
  • LDH has its poorest stability at 0°C

Clinical Significance

  • In myocardial infarction, LD increases 3-12 hours after the onset of pain
  • Peaks at 48-60 hours and remain elevated for 10-14 days
  • In MI, LD1 is higher than LD2, thus called “flipped” LD pattern
flipped ldh
flipped LDH

An inversion of the ratio of LD isoenzymes LD1 and LD2; LD1 is a tetramer of 4 H–heart subunits, and is the predominant cardiac LD isoenzyme;

Normally the LD1 peak is less than that of the LD2, a ratio that is inverted–flipped in 80% of MIs within the first 48 hrs DiffDx. LD flips also occur in renal infarcts, hemolysis, hypothyroidism, and gastric CA

creatine kinase ck
  • Is a cytosolic enzyme involved in the transfer of energy in muscle metabolism
  • Catalyzes the reversible phosphorylation of creatine by ATP
  • -Is a dimer comprised of two subunits, resulting in three CK isoenzymes
    • The B, or brain form
    • The M, or muscle form

Three isoenzymes isolated after electrophoresis:

  • CK-BB (CK1) isoenzyme
    • Is of brain origin and only found in the blood if the blood-brain barrier has been breached
  • CK-MM (CK3) isoenzyme
    • Accounts for most of the CK activity in skeletal muscle
  • CK-MB (CK2) isoenzyme
    • Has the most specificity for cardiac muscle
    • It accounts for only 3-20% of total CK activity in the heart
    • Is a valuable tool for the diagnosis of AMI because of its relatively high specificity for cardiac injury
    • Established as the benchmark and gold standard for other cardiac markers

Clinical Significance

  • -In myocardial infarction, CK will rise 4-6 hours after the onset of pain
  • -Peaks at 18-30 hours and returns to normal on the third day
  • -CK is the most specific indicator for myocardial infarction (MI)
  • Normal values: range varies according to age
  • Total Cholesterol: 150-250mg%
  • Cholesterol esters: 60-75% of the total cholesterol
cholesterol is advised if you
Cholesterol is advised if you
  • have been diagnosed with coronary heart disease, stroke or mini-stroke (TIA) or peripheral arterial disease (PAD)
  • are over 40
  • have a family history of early cardiovascular disease
  • have a close family member with cholesterol-related condition
  • are overweight
  • have high blood pressure, diabetes or a health condition that can increase cholesterol levels, such as an underactive thyroid
factors leading to raised cholesterol
Factors leading to raised cholesterol
  • an unhealthy diet: some foods already contain cholesterol (known as dietary cholesterol) but it is the amount of saturated fat in your diet which is more important
  • smoking: a chemical found in cigarettes called acrolein stops HDL from transporting LDL to the liver, leading to narrowing of the arteries (atherosclerosis)
  • having diabetes or high blood pressure(hypertension)
  • having a family history of stroke or heart disease
  • There is also an inherited condition known as familial hypercholesterolaemia (FH). This can cause high cholesterol even in someone who eats healthy diet.
  • Ester  derived from glycerol and three fatty acids.
  • Main lipids in the blood and important energy substrate.
  • Insoluble in water.
  • Hypertriglyceridemia
    • Not an important risk facotr for coronary artery disease.
    • It can cause pancreatitis when severe.

Both hypertriglyceridemia and hypercholesterolemia are associated with various types of cutaneous fat deposition and xanthomatas.


  • Very common clinical problem. Usually essential type meaning that have no identifiable cause.
  • Investigations for treatable causes like endocrine is necessary.

Anatomy of liver


Liver is the main source of synthesis of

  • Plasma proteins
    • Albumin
    • Globulin
  • Blood clotting factors
    • Prothrombin
    • Factors V, VII, and X
serum albumin
Serum albumin *
  • 3.5- 5.5 gm/dl


  • 2 -3.5 gm/dl


  • 6-8 gm/dl

Albumin/ Globulin ratio

  • 1.2:1 – 2.5: 1

Prothrombin time

reference range
Reference range
  • ALT ( upto 42 U/L)
  • AST (0-37 U/L)
  • ALP (65-306 U/L) raised in obstructive jaundice.
other enzymes
Other enzymes
  • GGT (11-60 u/l)
  • 5- NUCLEOTIDASE (2-17u/L)
  • LDH (180-360 u/l)
ggt or ggtp

Gamma GlutamylTranspeptidase. This enzyme level is elevated in case of liver disorders.   In contrast to the alkaline phosphatase, the GGT tends not to be elevated in diseases of bone, placenta, or intestine

prothrombin time
Prothrombin time
  • good correlation between abnormalities in prothrombin time and the degree of liver dysfunction.
  • Expressed in seconds and compared to a normal control patient's blood


  • serum iron,
  • the percent of iron saturated in blood,
  • the storage protein ferritin for hemochromatosis.
  • accumulation of copper in the liver in wilson disease.