Approach to Lab Investigations

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Approach to Lab Investigations

• By Mazen Badawi , MBBS
• Demonstrator , Department of Medicine
• KAAU

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General rules

• 1- order what you need
• 2- need is determined by criteria of diagnosis,
  or monitoring, or excluding
• 3- follow up what you ordered
• 4- your patient deserves knowing all about him
• 5- special instructions to patient and nurses
• 6- order sheet problems

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MI

• CK , AST, LDH not specific
• CK MB heart, MM muscle , BB brain
• AST heart, liver
• LDH heart, liver, RBCs, other

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MI
High AST

Look for ALT
Low ALT
High ALT
LIVER
HEART
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MI

• Troponin I
• C ? A ? L
• CK 6 hr to 3 days
• AST 12 to 6 days
• LDH 24 to 12 days
• Uses Confirm Dx, Timing, Efficacy of treatment

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CSF

• Sugar 0.4 0.8
• Protein 0.2 0.4
• Cells 0 5 lymphocytes
• Colorless

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CSF
AFB Gram stain Prot. Glucose Cell count Apperance
Normal
Bacterial meningitis
TB
aseptic
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CSF

• Protein- cell dissociation
• Acute guillian barre syndrome
• Paraplegia
• Cerebellar tumor
• Disseminated sclerosis

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CBC report

• Platelet 150 400 (x1000)
• RBC 4.5 5.5 (million)
• WBC 4 11 (x1000)
• Neutrophils 40-70 (2500-7500 absolute)
• Lymphocytes 20- 40
• BT in vivo, 2-4 min, punct ? dry ? stops ,
  measures
• CT in vitro , 4- 8 min, in tube, measures

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CBC

• What will happen if BM disease?

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CBC

• Normal retics 0.5 2
• Increase in hemorrhage, hemolysis, treated anemia
• Normoblasts is the same
• What does it mean if Retics are 0 ?

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CBC

• What is pokilocytosis? Anisocytosis?
• Both are seen in megaloblastic, hemolytic anemia

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CBC

• Number size shape of RBC
• Polycythemia check WBC, PLT. Why?

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CBC

• WBC
• Normal check diff
• High Neut or Ly Mono?
• Low Leucopenia

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Anemia
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(No Transcript)
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Urine report

• Volume 800 1400 ml
• PH 6
• Protein nil or trace
• Sugar nil
• Bilirubin nil or trace
• RBC 0-5
• WBC 0-5
• Crystals nil or
• Casts nil or hyaline
• Sp. Gravity 1015 - 1025

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What to look for

• Nephrotic syndrome proteinurea 3 g/ 24hr
• Normal urinary protein 0.150 gram
• Normal urinary albumin 0.01 gram
• Pus cells UTI
• Casts coagulated proteins
• Hyaline casts normal
• Granular renal failure
• Epithelial cells ATN
• White cell cast pyelonephritis

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polyurea
gt1010
1005
Fixed 1010
functional
DI
DM Sugar
CRF
Oligurea
gt1010
Fixed 1010
AGN RBC cast
Functional No RBC , hyaline cast
ARF
Ch. GN RBC cast
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Kidney Function Tests

• Blood urea dietary protein, tissue catabolism,
  liver funct, kidney funct
• Creatinine kidney funct, muscle mass
• Creatinine clearance calculated measured
• Other indices

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Renal function

• Calculated Creatinine clearance
• (140 age ) x wt X 0.85 female
• s. Cr
• Or measure it in 24 hr!

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Stool Analysis

• Fat, RBC, pus, mucus
• Normal Fat , RBC ve, Pus , Mucus

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Stool Analysis
Fat


RBC
Steatorrhea 6 Grams
DYSENTRY
Malabsorption
Maldigestion - Digested lt75
Bacillary Pus Mucus
Amoebic Pus Mucus
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LFT

• Bilirubin direct , total
• Protein total, albumin, globulin
• Enzymes ALT, AST, ALP
• Prothrombin time

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LFT

• ALP is very high in obstructive jaundice, bone
  lesions
• GGT increases in CLD esp. alcoholic
• Proteins 70- 90 mg , A/G ratio 2/1, in CLD 1/1
• Most specific

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High bilirubin Jaundic
Indirect More
Direct more
Both
Hemolytic
Obstructive
hepatocellular

• All normal except
• High indirect
• High LDH

High ALP

• A/G ratio
• Normal ALD
• - Decreased CLD

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TB

• Acid fast bacilli stain
• Acid fast bacilli culture
• PPD
• PCR
• Radiology

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HBV

• HBsAg 6 w ? 3 months, if persisted?
• HBsAb recovery immunity after 3 m
• HBc in Bx only
• HBc Ab all phases.IgM in replication
• HBeAg infective chronicity
• HBeAb low infectivity
• PCR best for replication

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Thank you