3. INTRODUCTION
• Laboratory tests are an invaluable aid to the practicing oral and
maxillofacial surgeon.
• In conjunction with a thorough history and physical examination,
laboratory tests available can aid in the diagnosis of various diseases
• allow the precise preoperative and postoperative management of patients
with systemic disease.
• In addition, patients without overt disease can be screened before
procedures that carry potentially serious complications, such as general
anesthesia, are begun.
3
5. FULL BLOOD COUNT (FBC)/ COMPLETE
BLOOD COUNT (CBC)
1. HB CONCENTRATION.
2. RED CELL COUNT.
3. RED CELL DISTRIBUTION WIDTH (RDW)
4. HAEMATOCRIT (HCT) / PCV.
5. MCV.
6. MCH.
7. MCHC.
8. WHITE CELL COUNT
9. WBC DIFFERENTIAL.
10. PLATELET COUNT.
5
6. HAEMOGLOBIN CONCENTRATION (HB)
• Defines anaemia (Hb <lower limit of normal adjusted for age and sex).
New born
16.5-19.5 g/dL
Children
11.2-16.5 g/dL
Males
14.0-18.0 g/dl
Females
12.0-16.0 g/dL
6
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
7. Red Blood Cell / Erythrocyte Count
• Children - 4.5-5.1 million/mm3
• Males - 4.6-6.2 million/mm3
• Females - 4.2-5.4 million/mm3
7
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
8. • Hypoproliferative anaemias, e.g. iron, vitamin B12
and folate deficiencies.
• Aplasia's e.g. idiopathic or drug-induced
• Parvovirus B19 infection-induced red cell aplasia
resulting in transient marked anaemia.
low red
cell count
• PRV.
high red
cell count
8
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
9. RED CELL DISTRIBUTION WIDTH (RDW)
• Measures the range of red cell size in a sample of blood
• ↓ MCV with normal RDW suggests thalassemia trait.
• ↓ MCV with high RDW suggests iron deficiency. blood
9
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
10. HAEMATOCRIT OR PCV
Polycythaemia.
High PCV
Anaemia (any cause).
Low PCV
10
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
Men: 47% ± 7.0%
Women: 42% ± 5.0%
The ratio of the volume of red blood cells to the total volume of blood.
11. MEAN CORPUSCULAR VOLUME (MCV)
• Volume of a single RBC in cubic microns.
• MCV =
𝑵𝒐𝒓𝒎𝒂𝒍 𝑷𝑪𝑽 𝒑𝒆𝒓 𝟏𝟎𝟎 𝒎𝒍 𝒃𝒍𝒐𝒐𝒅
𝑹𝑩𝑪 𝒄𝒐𝒖𝒏𝒕 𝒊𝒏 𝒎𝒊𝒍𝒍𝒊𝒐𝒏 /𝒄𝒖𝒎𝒎
𝒙 𝟏𝟎 µ³
• 80- 96 femtoliters /cell.
• normocytes
• Less- microcytes
• More- macrocytes
11
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
12. 12
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
13. MEAN CORPUSCULAR HEMOGLOBIN
• Average amount of hemoglobin in a single RBC in picogram
• MCH =
hemoglobin in gm%
𝑅𝐵𝐶 𝑐𝑜𝑢𝑛𝑡 𝑖𝑛 𝑚𝑖𝑙𝑙𝑖𝑜𝑛/𝑐𝑢𝑚
x 10 pg.
• 27 - 32 picograms / cell
Macrocytosis.
High Microcytosis,
e.g. iron deficiency
anaemia.
Low
13
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
14. MEAN CORPUSCULAR HEMOGLOBIN CONCENTRATION
• Hemoglobin Concentration in a single RBC.
• MCHC =
ℎ𝑏 𝑖𝑛 𝑔𝑚 %
𝑃𝐶𝑉 𝑝𝑒𝑟 100 𝑚𝑙 𝑏𝑙𝑜𝑜𝑑
x 100
• Normal range – normochromic ( 32-36 g/dl)
• Less- hypochromic
• More- hyperchromic
14
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
15. • Severe prolonged
dehydration.
• Hereditary spherocytosis..
High
• Iron deficiency anaemia.
• Thalassaemia.
Low
15
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
16. Total Leukocyte count
• 4–11 × 103 cells/mm3
16
Increased
Acute infections,
uremia, steroids,
hemorrhage,leukemia
Decreased
radiation, aplastic
anemia, infectious
mononucleosis
,septicemia
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
20. PLATELET COUNT
• Normal: 150,000-400,000/mm3
• Low count – thrombocytopenia
• High count - thrombocytosis
20
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
21. Increased
• Malignancy
• post surgery
• post splenectomy
• rheumatoid arthritis (RA)
• iron deficiency anemia
• trauma
• acute hemorrhage.
Decreased
• Idiopathic
thrombocytopenic purpura
(ITP)
• marrow invasion or aplasia
• Hypersplenism
• DIC
• cirrhosis
• quinidine
• massive transfusions
• viral infections
• Infectious mononucleosis
21
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
22. Recommendations for doing FBC
22
Routine Preoperative Testing In Adults Undergoing Elective Non-cardiothoracic Surgery , Joan Vlayen, Nadia Benahmed, Jo
Robays: KCE Report 280, Belgian health care knowledge centre.
23. COAGULATION TESTS
1. Bleeding time
2. Clotting time
3. PT
4. PTT
5. INR
23
Clinician’s Handbook of Oral and Maxillofacial Surgery, Daniel M. Laskin
24. BLEEDING TIME (BT)
• 1 to 6 minutes
• Increased: Thrombocytopenia, von Willibrand disease, aspirin therapy
24
• 6 to 10 minutes.
• Increased: Heparin therapy, clotting factor deficiency
Clotting Time(CT)
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
25. 25
Prothrombin time (PT)
• (12 to 14 seconds)
• Increased: warfarin, vitamin K deficiency, liver disease, DIC, prolonged use of tourniquet
before drawing blood
Partial thromboplastin time (PTT)
• (25 to 45 seconds)
• Increased: Heparin, defects in intrinsic clotting mechanism, hemophilia A and B, prolonged
use of tourniquet before drawing blood
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
26. Interpretation of PT and PTT in patients with bleeding disorders
• Liver disease, decreased vitamin K, decreased or
defective factor VII
PT prolonged, PTT
normal
• Decreased or defective factor VIII, IX, or XI or
anticoagulant present
PT normal, PTT
prolonged
• Decreased or defective factor I, II, V, or X, von
Willebrand disease, liver disease, DIC
PT and PTT
prolonged
• Decreased platelet function, thrombocytopenia,
factor XIII deficiency, mild von Willebrand disease
PT and PTT
normal
26
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
27. International normalized ratio (INR)
• Ratio of the patient’s PT to a control PT standardized for the potency
of the thromboplastin reagent developed by the World Health
Organization (WHO)
• INR = Patient PT
Control PT
• Normal value <1
27
Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based
Clinical Practice Guidelines
28. 28
• The guidelines of the American college of chest physicians (ACCP)
recommend dental surgery without vitamin k antagonists (VKA)
interruption with use of a pro hemostatic agent.
• The interruption of VKA treatment before dental procedures is not
recommended for interventions that are unlikely to cause bleeding for
low and high bleeding risk procedures if the INR of the patient is≤3.5
24 hours before the planned intervention.
• if the INR ≥3.5, the procedure should be delayed until INR values has
been reduced to ≤ 3.5.
Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based
Clinical Practice Guidelines
29. Calcium
• (8.5 to 10.5 mg/dL)
• Increased: Hyperparathyroidism, hypervitaminosis D, metastatic bone
tumors, Paget disease, multiple myeloma, sarcoidosis, chronic renal
failure
• Decreased: Hypoparathyroidism, hypoalbuminemia, renal failure,
alkalosis, acute pancreatitis, convulsions, vitamin D deficiency
29
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
30. Phosphorus
• (2.3 to 4.7 mg/dL)
• Increased: Hypoparathyroidism, chronic renal failure, acidosis,
hypervitaminosis D, Addison disease
• Decreased: Hyperparathyroidism, alcoholism, hypokalemia, vitamin D
deficiency, alkalosis, diabetes mellitus
30
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
32. Fasting Plasma Glucose (FPG)
• fasting blood sugar levels.
• not having anything to eat or drink (except water) for at least 8 hours
before the test.
32
33. Random Plasma Glucose Test
• This test is a blood check at any time of the day
• Diabetes is diagnosed at blood sugar of greater than or equal
to 200 mg/dl
33
34. GLYCATED HEMOGLOBIN TEST (HBA1C)
• determine how well you are managing your diabetes.
• Glucose enters your red blood cells and links up (or glycates) with molecules
of hemoglobin
• HbA1c reflects average plasma glucose over the previous eight to 12 weeks
34
35. NICE 2016 GUIDELINES
Offer HbA1c testing to people with diabetes having
surgery if they have not been tested in the last 3
months.
Do not routinely offer HbA1c testing before surgery
to people without diagnosed diabetes.
35
38. 1. Electrolytes
Sodium
(135 to 145 mEq/L)
• Increased: Dehydration, glycosuria, diabetes insipidus
• Decreased: Diuretic use, congestive heart failure,
hyperglycemia, renal failure, vomiting, diarrhoea.
38
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
39. Chloride
• (95 to 108 mEq/L)
• Increased: Dehydration, non anion gap metabolic acidosis,
diarrhoea, diabetes insipidus
• Decreased: Vomiting, excess sweating, congestive heart
failure, chronic renal failure, diuretic use, SIADH, diabetes
mellitus with ketoacidosis
39
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
40. Potassium
(3.5 to 5.2 mEq/L)
• Increased: Renal failure, adrenal insufficiency, acidosis,
hemolysis, medications, iatrogenic
• Decreased: Diuretic therapy, alkalosis, vomiting, nasogastric
suctioning, mineralocorticoid excess
40
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
41. Bicarbonate
(24 to 30 mEq/L)
• Increased: Dehydration, respiratory acidosis, emphysema, vomiting,
metabolic alkalosis
• Decreased: Metabolic acidosis, respiratory alkalosis, renal failure,
diarrhoea.
41
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
42. 2.ANION GAP
(8 to 12 mEq)
Difference in mEq between
serum sodium and the sum
of serum chloride and
bicarbonate
• Diarrhoea, renal tubular
acidosis
Normal
• Renal failure, lactic
acidosis, ketoacidosis,
salicylate toxicity
Increased
• Disseminated
intravascular coagulation,
multiple myeloma
Decreased
42
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
43. 3. Renal Function
Blood urea nitrogen (BUN)
(6 to 20 mg/dL)
• Increased: Renal failure of all types, dehydration, gastrointestinal
bleeding, increased protein catabolism
• Decreased: Liver damage, protein deficiency, starvation, overhydration
43
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
44. Creatinine
(0.7 to 1.4 mg/dL)
• Increased: Renal failure, muscle disease, false positives with diabetic
ketoacidosis
• Decreased: Pregnancy; rarely clinically significant
44
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
45. 4. LIVER FUNCTION
45
• bile pigments, bile salts, bromosulphthalein.
Tests based on
excretory function
• transaminases, alkaline phosphatase, 5'nucleotidase y-
glutamyl transpeptidase.
Tests based on serum
enzymes
• Galactose tolerance, antipyrine clearance.
Tests based on
metabolic capacity
• Prothrombin time, serum albumin.
Tests based on
synthetic functions
• Hippuric acid synthesis.
Tests based on
detoxification
Biochemistry , Dr. U Satyanarayana
46. 46
Textbook of Biochemistry for Dental Students Third Edition, Dm Vasudevan, Sreekumari S,kannan Vaidyanathan
47. 1. SERUM BILIRUBIN
• Total - 0.2- 1.0 mg/dL
• conjugated bilirubin - 0.2-0.4mg/dl
• Unconjugated bilirubin - 0.2-0.6 mg/dl.
• estimated by van den Bergh reaction.
47
Biochemistry , Dr. U Satyanarayana
48. 48
Textbook of Biochemistry for Dental Students Third Edition, Dm Vasudevan, Sreekumari S,kannan Vaidyanathan
49. 2. Urinary Bilirubin & Urobilinogen
• In all cases of jaundice, urine should be examined for the presence of
bile pigments (bilirubin), bile salts and urobilinogen
49
Textbook of Biochemistry for Dental Students Third Edition, Dm Vasudevan, Sreekumari S,kannan Vaidyanathan
54. 1.HIV
• Enzyme-linked immunosorbent assay (ELISA) (screening test)
• Western blot: Used for confirming presence of HIV antibody
• Positive: AIDS, AIDS-related complex
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Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
55. 2.HBsAg
• hepatitis B virus (HBV).
• A "positive" or "reactive" HBsAg test result means that the
person is infected with hepatitis B.
• can spread the hepatitis B virus to others through blood.
55
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
56. 3. VDRL
• Venereal disease research laboratory test.
• screening test for syphilis.
• If positive , confirm the results with an FTA-ABS test.
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Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
57. COVID - 19
• Nucleic acid amplification tests (NAAT)
• detection of COVID-19 virus nucleic acid (RNA) by real time RT-PCR assays.
• RNA isolated and purified from upper and lower respiratory specimens is
reverse transcribed to cDNA and subsequently amplified
• The viral genes targeted so far include the N, E, S and RdRP genes.
• E gene as screening, followed by confirmation through the detection of RdRP
gene
57
1.Molecular methods
World Health Organization. (2020). Laboratory testing for coronavirus disease 2019 (COVID-19) in suspected human cases:
interim guidance, 2 March 2020
58. 2.Serological methods
• detection of IgM / IgG antibodies
3. Antigen detection
• During the first days after symptom onset (1 to 5), viral proteins can be detected.
4. Rapid diagnostic tests (RDTs)
So far there are no rapid diagnostic tests have been authorized by competent
regulatory authorities
58
World Health Organization. (2020). Laboratory testing for coronavirus disease 2019 (COVID-19) in suspected human cases:
interim guidance, 2 March 2020
60. C-reactive protein (CRP)
• acute phase protein
• Normal value- less than 10mg/l
• sensitive systemic marker of inflammation and tissue damage.
• During infectious or inflammatory disease states, CRP levels rise
rapidly within the first 6 to 8 hours and peak at levels of up to 350–
400 mg/L after 48 hours
• CRP, binds to pathogens and activates the complement to enhance
opsonisation and clearance, even before the production of specific IgM
or IgG
60
63. Blood Gases
• Altered ventilatory status:
stroke, asthma, COPD
• Hypoxemia: pneumonia
• Hypocapnia: hyperventilation
• Hypercapnia: COPD
• pH disturbance: ketoacidosis
Indications
for
Measurement
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Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
64. Normal Values—Arterial Blood Sample
• PO2 - 80 to 95 mm Hg
• SaO2 - 93% to 98%
• PCO2 - 36 to 43 mm Hg
• HCO3 : 20 to 30 mEq/L
• Arterial pH: 7.35 to 7.45
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Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
65. Interpretation of Arterial Blood Gas Results
• Arterial pH
• < 7.35 = acidosis
• 7.35 to 7.45 = normal, compensated, or mixed disorder
• > 7.45 = alkalosis
65
Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
71. 71
Routine Preoperative Testing In Adults Undergoing Elective Non-cardiothoracic Surgery , Joan Vlayen, Nadia Benahmed, Jo
Robays: KCE Report 280
72. CONCLUSION
• Preoperative laboratory tests should be ordered based on
defined indications such as positive findings on a history and
physical exam.
• A thorough history and physical examination can be used to
identify those medical conditions that might affect
perioperative management and direct further laboratory
testing.
72
73. REFERENCES
1. Clinician’s Handbook of Oral and Maxillofacial Surgery, Daniel M. Laskin
2. Oxford Handbook of Clinical and Laboratory Investigation, Drew Provan, Andrew Krentz
3. Biochemistry , Dr. U Satyanarayana
4. Textbook of Biochemistry for Dental Students Third Edition, Dm Vasudevan, Sreekumari S,kannan Vaidyanathan
5. Textbook of physiology ,6th edition, A K Jain
6. Peterson’s Principles Of Oral And Maxillofacial Surgery Second Edition
7. C-reactive protein concentrations as a marker of inflammation or infection for interpreting biomarkers of micronutrient
status –WHO
8. Routine preoperative tests for elective surgery - NICE guideline
9. World Health Organization. (2020). Laboratory testing for coronavirus disease 2019 (COVID-19) in suspected human
cases: interim guidance, 2 March 2020
10. Routine Preoperative Testing In Adults Undergoing Elective Non-cardiothoracic Surgery , Joan Vlayen, Nadia Benahmed,
Jo Robays: KCE Report 280
11. NICE guidelines 2016
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