Blood Tests: Difference between revisions
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Pathology<br>Biochemistry<br>Haematology (blood bank)<br>Microbiology <br>Histology<br>Cytology<br>Immunology | Pathology<br>Biochemistry<br>Haematology (blood bank)<br>Microbiology <br>Histology<br>Cytology<br>Immunology | ||
=== Use of Pathology Tests === | ==== Use of Pathology Tests ==== | ||
Diagnosis: to confirm or refute<br>Prognosis: risk factors<br>Monitoring: progress & treatment<br>Screening: subclinical presence of pathology | Diagnosis: to confirm or refute<br>Prognosis: risk factors<br>Monitoring: progress & treatment<br>Screening: subclinical presence of pathology | ||
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Age<br>Sex<br>Pregnancy<br>Posture<br>Exercise<br>Stress<br>Nutritional state<br>Time<br>Other medical intervention<br> | Age<br>Sex<br>Pregnancy<br>Posture<br>Exercise<br>Stress<br>Nutritional state<br>Time<br>Other medical intervention<br> | ||
== Chemical Pathology == | == Chemical Pathology == | ||
NB reference ranges apply to adults only | NB reference ranges apply to adults only | ||
==== Water and sodium Na: 135-145 mmol/l<br> | ==== Water and sodium ==== | ||
Na: 135-145 mmol/l<br> | |||
↓Na (from skin, kidneys, gut) – weakness, postural hypotension, syncope, wt loss, cv changes, decreased skin turgor. <br>↑Na (incr. intake, decr. Excretion) – oedema, pulmonary oedema, HT, effusions | ↓Na (from skin, kidneys, gut) – weakness, postural hypotension, syncope, wt loss, cv changes, decreased skin turgor. <br>↑Na (incr. intake, decr. Excretion) – oedema, pulmonary oedema, HT, effusions | ||
==== Potassium K: 3.4-5.2 mmol/l<br> | ==== Potassium ==== | ||
K: 3.4-5.2 mmol/l<br> | |||
↓K (alkalosis, RF, D&V,diuretics) – Weakness, ileus, hypotonia, confusion, depression, arrhythmias, alkalosis.<br>↑K (catabolism, acidosis, RF) – Cardiac arrest with VF. | ↓K (alkalosis, RF, D&V,diuretics) – Weakness, ileus, hypotonia, confusion, depression, arrhythmias, alkalosis.<br>↑K (catabolism, acidosis, RF) – Cardiac arrest with VF. | ||
== Renal Function Tests<br> == | == Renal Function Tests<br> == | ||
==== Urea & creatinine U: 2.5-6.5 mmol/l Cr: 60-120μmol/l<br> | ==== Urea & creatinine ==== | ||
U: 2.5-6.5 mmol/l Cr: 60-120μmol/l<br> | |||
Both should rise together in renal failure. Creat is the more accurate measurement, urea is affected more by diet and dehydration.<br>Creatinine Clearance Crcl: 100-120mls/min<br>Measures glomerular filtration rate and permeability | Both should rise together in renal failure. Creat is the more accurate measurement, urea is affected more by diet and dehydration.<br>Creatinine Clearance Crcl: 100-120mls/min<br>Measures glomerular filtration rate and permeability | ||
==== Enzymes<br> ==== | ==== Enzymes<br> ==== | ||
-non specific<br>-have a specific time window of elevation | -non specific<br>-have a specific time window of elevation | ||
==== Alkaline phosphatase alk: 30-120 IU/l<br> | ==== Alkaline phosphatase ==== | ||
alk: 30-120 IU/l<br> | |||
↑ - Pagets, osteomalacia, bone tumours, healing #, osteomyelitis.<br>Cholestasis, cirrhosis, hepatitis, liver tumour. | ↑ - Pagets, osteomalacia, bone tumours, healing #, osteomyelitis.<br>Cholestasis, cirrhosis, hepatitis, liver tumour. | ||
==== Alanine transaminase <br> ==== | ==== Alanine transaminase <br> ==== | ||
Alt/GPT: <40 IU/l<br> | Alt/GPT: <40 IU/l<br> | ||
↑ - Acute and chronic hepatitis, liver necrosis, tissue hypoxaemia and crush injuries, cholestasis & other liver diseases. | ↑ - Acute and chronic hepatitis, liver necrosis, tissue hypoxaemia and crush injuries, cholestasis & other liver diseases. | ||
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Creatine kinase CK: ♂40-215 ♀40-185 IU/l<br>↑ - MI, rhabdomyolisis, Sk. Muscle trauma, MD, severe exercise | Creatine kinase CK: ♂40-215 ♀40-185 IU/l<br>↑ - MI, rhabdomyolisis, Sk. Muscle trauma, MD, severe exercise | ||
==== Enzymes and MIs<br> ==== | ==== Enzymes and MIs<br> ==== | ||
-Troponin T (Trop T) rises within hours & remains elevated for days. Results reported as neg, pos or some myocardial damage. | -Troponin T (Trop T) rises within hours & remains elevated for days. Results reported as neg, pos or some myocardial damage. | ||
-CK:<br> | -CK:<br> | ||
At 3hrs, 25% of MIs have raised CKs<br>At 6hrs, 72% “ “ “ “ “<br>At 9hrs, 97% “ “ “ “ “ | At 3hrs, 25% of MIs have raised CKs<br>At 6hrs, 72% “ “ “ “ “<br>At 9hrs, 97% “ “ “ “ “ | ||
==== Gamma glutamyl tranferase γGT/GTP: ♂<65 ♀<55 IU/l<br> | ==== Gamma glutamyl tranferase ==== | ||
γGT/GTP: ♂<65 ♀<55 IU/l<br> | |||
↑ Liver disease esp. Cholestasis, alcoholic liver disease, cirrhosis, hepatitis | ↑ Liver disease esp. Cholestasis, alcoholic liver disease, cirrhosis, hepatitis | ||
==== Amylase Amy: <100 IU/l<br> | ==== Amylase ==== | ||
Amy: <100 IU/l<br> | |||
↑ Acute pancreatitis<br>other abdo disorders, RF | ↑ Acute pancreatitis<br>other abdo disorders, RF | ||
== Thyroid diseases<br> == | == Thyroid diseases<br> == | ||
'''Hyperthyroidism''' (Graves disease, multinodular goitre, adenoma) – weight loss, sweating, palpitation, angina, tremor, diarrhea, muscle weakness, goitre, eyelid retraction.<br>'''Hypothyroidism''' (Hashimotos disease, post surgery, congenital, secondary to pituitary/hypothalamic disease)<br>- lethargy, cold intolerance, dry coarse skin & hair, hoarseness, wt gain, slow reflexes & muscle relaxation. Others including: anaemia, psychosis, constipation bradycardia, CTS, infertility.<br> | '''Hyperthyroidism''' (Graves disease, multinodular goitre, adenoma) – weight loss, sweating, palpitation, angina, tremor, diarrhea, muscle weakness, goitre, eyelid retraction.<br>'''Hypothyroidism''' (Hashimotos disease, post surgery, congenital, secondary to pituitary/hypothalamic disease)<br>- lethargy, cold intolerance, dry coarse skin & hair, hoarseness, wt gain, slow reflexes & muscle relaxation. Others including: anaemia, psychosis, constipation bradycardia, CTS, infertility.<br> | ||
==== Thyroid Function Testing: | ==== Thyroid Function Testing: ==== | ||
TSH 0.3-5mU/l<br> | |||
>15mU/l - 1° hypothyroidism<br> | |||
<0.3mU/l - Further investigations! <br> | 0.3-5mU/l - euthyroid (normal) | ||
<0.3mU/l - Further investigations! <br> | |||
Interpretation complicated by:<br>-Many medications, hormones<br>-Any acute illness – “sick euthyroidism” all thyroid tests are low.<br>-Recovery – TSH raised. | Interpretation complicated by:<br>-Many medications, hormones<br>-Any acute illness – “sick euthyroidism” all thyroid tests are low.<br>-Recovery – TSH raised. | ||
==== Glucose: Fasting 3-5.5 mmol/l <br> | ==== Glucose: ==== | ||
Fasting 3-5.5 mmol/l <br> | |||
>7.8 – diagnostic of DM<br> 5.5-7.8 – impaired glucose tolerance | >7.8 – diagnostic of DM<br> 5.5-7.8 – impaired glucose tolerance | ||
==== Hyperglycaemia<br> ==== | ==== Hyperglycaemia<br> ==== | ||
Thirst, polyuria, dehydration, hypotension, tachycardia, drowsiness.<br>(and for IDDM, DKA) ketosis, hyperventilation, vomiting. | Thirst, polyuria, dehydration, hypotension, tachycardia, drowsiness.<br>(and for IDDM, DKA) ketosis, hyperventilation, vomiting. | ||
==== Hypoglycaemia<br> ==== | ==== Hypoglycaemia<br> ==== | ||
Tiredness, confusion, detachment, ataxia, blurred vision, dizziness, paraesthesia, hemiparesis, convulsions, coma | Tiredness, confusion, detachment, ataxia, blurred vision, dizziness, paraesthesia, hemiparesis, convulsions, coma | ||
==== Lactate <2.0 mmol/l<br> | ==== Lactate ==== | ||
<2.0 mmol/l<br> | |||
↑ mainly due to tissue hypoxia (decreased perfusion or decr. PO2) | ↑ mainly due to tissue hypoxia (decreased perfusion or decr. PO2) | ||
== Proteins<br> == | == Proteins<br> == | ||
==== Albumin alb: 36-50 g/l<br> | ==== Albumin ==== | ||
alb: 36-50 g/l<br> | |||
– Maintains oncotic pressure (keeps fluid in vessels)<br>- Transports small drugs, calcium & hormones<br>↓ (Many causes incl. malnutrition, liver disease, overhydration, incr. cap. Permeability, protein losing states, burns, haemorrhage, general catabolism-sepsis, fever, malignancy, trauma)<br>Symptoms – oedema! (Unresponsive to diuretics or elevation) | – Maintains oncotic pressure (keeps fluid in vessels)<br>- Transports small drugs, calcium & hormones<br>↓ (Many causes incl. malnutrition, liver disease, overhydration, incr. cap. Permeability, protein losing states, burns, haemorrhage, general catabolism-sepsis, fever, malignancy, trauma)<br>Symptoms – oedema! (Unresponsive to diuretics or elevation) | ||
==== C-reactive protein | ==== C-reactive protein ==== | ||
CRP: <5mg/l<br> | |||
==== Uric acid/Urate 0.1-0.4 mmol/l<br> | An ‘acute phase’ protein <br>-Monitoring infections (>100, more likely to be bacterial)<br>-Distinguishing between AI diseases and active infection<br>-Monitoring RA Rx<br>-Checking for post-op infection <br>More sensitive than ESR<br> | ||
==== Uric acid/Urate ==== | |||
0.1-0.4 mmol/l<br> | |||
Incr. production/decr. Excretion → gout (exquisite pain and inflammation often in 1st MTP joint)<br>>0.54 mM → 50% chance of developing gout | Incr. production/decr. Excretion → gout (exquisite pain and inflammation often in 1st MTP joint)<br>>0.54 mM → 50% chance of developing gout | ||
== Tumour Markers<br> == | == Tumour Markers<br> == | ||
-Chemicals related to the presence/progress of a tumour<br>-Either secreted by tumours or cell surface antigens<br>-Of greater prognostic than diagnostic use, should always be interpreted in the light of clinical and other diagnostic findings. | -Chemicals related to the presence/progress of a tumour<br>-Either secreted by tumours or cell surface antigens<br>-Of greater prognostic than diagnostic use, should always be interpreted in the light of clinical and other diagnostic findings. | ||
==== Carcinoembryonic Antigen | ==== Carcinoembryonic Antigen ==== | ||
CEA 2-5μg/l<br> | |||
-Monitoring/detection of colorectal, gastric, breast, bronchial, bronchial and some ovarian cancers.<br>-Modestly elevated levels in a variety of non-malignancies | -Monitoring/detection of colorectal, gastric, breast, bronchial, bronchial and some ovarian cancers.<br>-Modestly elevated levels in a variety of non-malignancies | ||
==== Alpha Fetoprotein | ==== Alpha Fetoprotein ==== | ||
AFP <9 KU/l<br> | |||
-Monitoring/detecting liver cancers, testicular cancer.<br>-Also raised in pregnancy, hepatic regeneration. | -Monitoring/detecting liver cancers, testicular cancer.<br>-Also raised in pregnancy, hepatic regeneration. | ||
==== Human Chorionic Gonadotrophin | ==== Human Chorionic Gonadotrophin ==== | ||
βHCG <5IU/l<br> | |||
-Diagnosis and monitoring of choriocarcinoma, also testicular tumours.<br>-Also used to detect ectopic pregnancies. | -Diagnosis and monitoring of choriocarcinoma, also testicular tumours.<br>-Also used to detect ectopic pregnancies. | ||
==== Prosate Specific Antigen (PSA) <br> ==== | ==== Prosate Specific Antigen (PSA) <br> ==== | ||
-Monitoring/detecting prostate cancer<br>-May be raised in benign prostatic hypertrophy | -Monitoring/detecting prostate cancer<br>-May be raised in benign prostatic hypertrophy | ||
==== CA 125 | ==== CA 125 ==== | ||
<35 IU/l<br> | |||
-96% of patients with ovarian cancer have raised levels | -96% of patients with ovarian cancer have raised levels | ||
==== CA 19-9 | ==== CA 19-9 ==== | ||
<60 IU/l<br> | |||
-Elevated in patients with pancreatic tumours | -Elevated in patients with pancreatic tumours | ||
==== CA15-3<br> ==== | ==== CA15-3<br> ==== | ||
-Elevated in 70% of patients with metastatic breast cancer. A good marker for monitoring Rx. | -Elevated in 70% of patients with metastatic breast cancer. A good marker for monitoring Rx. | ||
==== Paraproteins<br> ==== | ==== Paraproteins<br> ==== | ||
-Elevated in 98% of patients with myeloma (and other malignancies of B-cells.<br>-Myeloma is a haematological malignancy the symptoms of which are anaemia, bone pain (esp LBP) and pathological #s. | -Elevated in 98% of patients with myeloma (and other malignancies of B-cells.<br>-Myeloma is a haematological malignancy the symptoms of which are anaemia, bone pain (esp LBP) and pathological #s. | ||
== Immunology<br> == | == Immunology<br> == | ||
=== Auto-immune profile:<br> === | |||
Anti-nuclear antibody (ANA)<br> ==== | |||
Anti-nuclear antibody (ANA)<br> ==== | |||
Associated with “connective tissue disease” positive in 95% of SLE, also found in JCA, Sjogren’s syndrome, fibrosing alveolitis<br> | Associated with “connective tissue disease” positive in 95% of SLE, also found in JCA, Sjogren’s syndrome, fibrosing alveolitis<br> | ||
==== Anti-mitochondrial antibodies (AMA)<br> ==== | ==== Anti-mitochondrial antibodies (AMA)<br> ==== | ||
positive in >95% of primary biliary cirrhosis.<br> | positive in >95% of primary biliary cirrhosis.<br> | ||
==== Anti-smooth muscle antibodies (ASMA)<br> ==== | ==== Anti-smooth muscle antibodies (ASMA)<br> ==== | ||
Positive in 50-70% of autoimmune “lupoid” hepatitis<br> | Positive in 50-70% of autoimmune “lupoid” hepatitis<br> | ||
==== Rheumatoid factor (RF)<br> ==== | ==== Rheumatoid factor (RF)<br> ==== | ||
(anti-IgG antibodies) Positive in 70% of RA (but lots of false positives). Should only be used to screen, NOT monitor, (use C-RP instead) | (anti-IgG antibodies) Positive in 70% of RA (but lots of false positives). Should only be used to screen, NOT monitor, (use C-RP instead) | ||
==== Anti-Reticulin Antibodies.<br> ==== | ==== Anti-Reticulin Antibodies.<br> ==== | ||
-Present in Coeliac disease. Also Crohns and UC. | -Present in Coeliac disease. Also Crohns and UC. | ||
=== Others:<br> === | === Others:<br> === | ||
==== Anti-acetylcholine receptor antibody <br> ==== | ==== Anti-acetylcholine receptor antibody <br> ==== | ||
Positive in 80-95% MG | Positive in 80-95% MG | ||
==== Anti-cardiolipin antibody<br> ==== | ==== Anti-cardiolipin antibody<br> ==== | ||
Anti-phospholipid syndrome (recurrent abortion, thromboses, thrombocytopaenia) | Anti-phospholipid syndrome (recurrent abortion, thromboses, thrombocytopaenia) | ||
==== Anti-dsDNA antibody<br> ==== | ==== Anti-dsDNA antibody<br> ==== | ||
Strongly suggestive of SLE | Strongly suggestive of SLE | ||
==== Anti-ENA (extractable nuclear antigen) Antibody<br> ==== | ==== Anti-ENA (extractable nuclear antigen) Antibody<br> ==== | ||
Used to classify connective tissue diseases | Used to classify connective tissue diseases | ||
==== Anti-Intrinsic Factor antibody<br> ==== | ==== Anti-Intrinsic Factor antibody<br> ==== | ||
Positive in 70% of pernicious anaemia | Positive in 70% of pernicious anaemia | ||
==== Anti-neutrophil cytoplasmic antibody (ANCA)<br> ==== | ==== Anti-neutrophil cytoplasmic antibody (ANCA)<br> ==== | ||
Wegener’s granulomatosis, microsopic arteritis | Wegener’s granulomatosis, microsopic arteritis | ||
==== Anti-thyroid antibody<br> ==== | ==== Anti-thyroid antibody<br> ==== | ||
95% positive in Hashimotos thyroiditis<br>90% positive in primary myxoedema<br>18% positive in Graves disease<br> | 95% positive in Hashimotos thyroiditis<br>90% positive in primary myxoedema<br>18% positive in Graves disease<br> | ||
== Haematology<br> == | == Haematology<br> == | ||
Coagulation studies -Measure the clotting mechanisms, for diagnosis and extent of disorder. | Coagulation studies -Measure the clotting mechanisms, for diagnosis and extent of disorder. | ||
==== Heparin<br> ==== | ==== Heparin<br> ==== | ||
'''Therapeutic administration'''<br>-DVT, PE<br>-MI, Unstable Angina<br>-Acute peripheral occlusion.<br>'''Prophylactic administration'''<br>->30 mins GA with post-op bed rest.<br>-High risk patients.<br> | '''Therapeutic administration'''<br>-DVT, PE<br>-MI, Unstable Angina<br>-Acute peripheral occlusion.<br>'''Prophylactic administration'''<br>->30 mins GA with post-op bed rest.<br>-High risk patients.<br> | ||
'''Pregnancy'''<br> | '''Pregnancy'''<br> | ||
The anticoagulant of choice for women requiring anticoagulation<br>'''Relevant side effects'''<br>-Haemorrhage<br>-Thrombocytopaenia<br>-Osteoporosis<br>'''Monitoring of Heparin'''<br>Low dose subcut. – <br>no laboratory control required<br>Continuous iv infusion or full dose subcut. – <br> APTT (activated partial thromboplastin time) should <br> be between 50-75 seconds. Caution with high values <br> (>100) re spontaneous bleeding. | The anticoagulant of choice for women requiring anticoagulation<br>'''Relevant side effects'''<br>-Haemorrhage<br>-Thrombocytopaenia<br>-Osteoporosis<br>'''Monitoring of Heparin'''<br>Low dose subcut. – <br>no laboratory control required<br>Continuous iv infusion or full dose subcut. – <br> APTT (activated partial thromboplastin time) should <br> be between 50-75 seconds. Caution with high values <br> (>100) re spontaneous bleeding. | ||
==== Warfarin<br> ==== | ==== Warfarin<br> ==== | ||
-Patients require close monitoring of INR (International Normalized Ratio).<br>-Target INR ranges are 2-3 for moderate anticoagulation and 3-4.5 for more intensive therapy.<br>-These doses may fluctuate with no clinical significance.<br>-Warfarin requirements may be dramatically changed by:<br>illness<br>change in diet<br>change in other medication<br>'''International normalized ratio (INR) <br>>10 Life threatening haemorrhage can occur.'''<br>>4.5 Caution re spontaneous bleeding<br>-Always be wary of patients with mild haemorrhage such as haematuria or epistaxis (nosebleed).<br> | -Patients require close monitoring of INR (International Normalized Ratio).<br>-Target INR ranges are 2-3 for moderate anticoagulation and 3-4.5 for more intensive therapy.<br>-These doses may fluctuate with no clinical significance.<br>-Warfarin requirements may be dramatically changed by:<br>illness<br>change in diet<br>change in other medication<br>'''International normalized ratio (INR) <br>>10 Life threatening haemorrhage can occur.'''<br>>4.5 Caution re spontaneous bleeding<br>-Always be wary of patients with mild haemorrhage such as haematuria or epistaxis (nosebleed).<br> | ||
==== Full Blood Count (FBC)<br> ==== | ==== Full Blood Count (FBC)<br> ==== | ||
===== Red blood cell count (RBC) ♂4.5-6.5 ♀3.5-5.8 <br> ===== | ===== Red blood cell count (RBC) ♂4.5-6.5 ♀3.5-5.8 <br> ===== | ||
↓anaemias, Hodgkins disease, myeloma, leukaemia, haemorrhage, SLE, rheumatic fever and chronic infection.<br>↑polycythaemia, renal disorders, decr. plasma vol: (severe burns, shock, vomiting)<br> | ↓anaemias, Hodgkins disease, myeloma, leukaemia, haemorrhage, SLE, rheumatic fever and chronic infection.<br>↑polycythaemia, renal disorders, decr. plasma vol: (severe burns, shock, vomiting)<br> | ||
===== Haemoglobin (Hb) ♂13-18 ♀12-16<br> ===== | ===== Haemoglobin (Hb) ♂13-18 ♀12-16<br> ===== | ||
↓anaemia, hyperthyroidism, liver/kidney disease, many CAs (especially haematological) SLE<br>↑haemoconcentration disorders: burns, polycythaemia, COPD, CCF.<br><5 can lead to MI<br>>20 can lead to clogging of capillaries.<br> | ↓anaemia, hyperthyroidism, liver/kidney disease, many CAs (especially haematological) SLE<br>↑haemoconcentration disorders: burns, polycythaemia, COPD, CCF.<br><5 can lead to MI<br>>20 can lead to clogging of capillaries.<br> | ||
===== White blood cell count (WBC)<br> ===== | ===== White blood cell count (WBC)<br> ===== | ||
A useful guide to the severity of a disease process<br>'''Neutrophils 2.5-7.5<br>Lymphocytes 1-3.5<br>Monocytes 0.2-0.8<br>Eosinophils 0.04-0.4<br>Basophils 0.01-0.1''' | A useful guide to the severity of a disease process<br>'''Neutrophils 2.5-7.5<br>Lymphocytes 1-3.5<br>Monocytes 0.2-0.8<br>Eosinophils 0.04-0.4<br>Basophils 0.01-0.1''' | ||
'''Neutrophilia'''(↑) bacterial infections, gout, uraemia, poisoning, haemorrhage, haemolysis, necrosis.<br>'''Neutropaenia'''(↓) bacterial infections (poor prognosis) viral infections, certain anaemias, blood cancers, anaphylactic shock.<br>'''Eosinophilia'''(↑) Allergic reactions, parasitic diseases, certain blood cancers, skin infections, immunodeficiency disorders.<br>-Other variations occur in the specific white blood cell differential count with conditions such as: anaemias, blood cancers, infections, and certain inflammatory disorders. | '''Neutrophilia'''(↑) bacterial infections, gout, uraemia, poisoning, haemorrhage, haemolysis, necrosis.<br>'''Neutropaenia'''(↓) bacterial infections (poor prognosis) viral infections, certain anaemias, blood cancers, anaphylactic shock.<br>'''Eosinophilia'''(↑) Allergic reactions, parasitic diseases, certain blood cancers, skin infections, immunodeficiency disorders.<br>-Other variations occur in the specific white blood cell differential count with conditions such as: anaemias, blood cancers, infections, and certain inflammatory disorders. | ||
===== Platelets (150-400) ===== | ===== Platelets (150-400) ===== | ||
'''Thrombocytosis'''(↑) malignancies, polycythaemia, RA & other inflammatory diseases, acute infections, <br>'''Thrombocytopaenia'''(↓) toxic affects of drugs, esp. chemotherapy, allergies, anaemias, viral infections, post transfusion, ITP.<br>Caution with low values re spontaneous bleeding, and bruising.<br><br> | '''Thrombocytosis'''(↑) malignancies, polycythaemia, RA & other inflammatory diseases, acute infections, <br>'''Thrombocytopaenia'''(↓) toxic affects of drugs, esp. chemotherapy, allergies, anaemias, viral infections, post transfusion, ITP.<br>Caution with low values re spontaneous bleeding, and bruising.<br><br> |
Revision as of 23:13, 9 March 2009
Original Editor - John Mitchell Lead Editors - If you would like to be a lead editor on this page, please contact us. |
An Introduction To Pathology[edit | edit source]
Pathology
Biochemistry
Haematology (blood bank)
Microbiology
Histology
Cytology
Immunology
Use of Pathology Tests[edit | edit source]
Diagnosis: to confirm or refute
Prognosis: risk factors
Monitoring: progress & treatment
Screening: subclinical presence of pathology
Interpretation[edit | edit source]
Is it normal?
Is it different?
Is it consistent with clinical findings?
Factors affecting results[edit | edit source]
Age
Sex
Pregnancy
Posture
Exercise
Stress
Nutritional state
Time
Other medical intervention
Chemical Pathology[edit | edit source]
NB reference ranges apply to adults only
Water and sodium[edit | edit source]
Na: 135-145 mmol/l
↓Na (from skin, kidneys, gut) – weakness, postural hypotension, syncope, wt loss, cv changes, decreased skin turgor.
↑Na (incr. intake, decr. Excretion) – oedema, pulmonary oedema, HT, effusions
Potassium[edit | edit source]
K: 3.4-5.2 mmol/l
↓K (alkalosis, RF, D&V,diuretics) – Weakness, ileus, hypotonia, confusion, depression, arrhythmias, alkalosis.
↑K (catabolism, acidosis, RF) – Cardiac arrest with VF.
Renal Function Tests
[edit | edit source]
Urea & creatinine [edit | edit source]
U: 2.5-6.5 mmol/l Cr: 60-120μmol/l
Both should rise together in renal failure. Creat is the more accurate measurement, urea is affected more by diet and dehydration.
Creatinine Clearance Crcl: 100-120mls/min
Measures glomerular filtration rate and permeability
Enzymes
[edit | edit source]
-non specific
-have a specific time window of elevation
Alkaline phosphatase[edit | edit source]
alk: 30-120 IU/l
↑ - Pagets, osteomalacia, bone tumours, healing #, osteomyelitis.
Cholestasis, cirrhosis, hepatitis, liver tumour.
Alanine transaminase
[edit | edit source]
Alt/GPT: <40 IU/l
↑ - Acute and chronic hepatitis, liver necrosis, tissue hypoxaemia and crush injuries, cholestasis & other liver diseases.
Creatine kinase CK: ♂40-215 ♀40-185 IU/l
↑ - MI, rhabdomyolisis, Sk. Muscle trauma, MD, severe exercise
Enzymes and MIs
[edit | edit source]
-Troponin T (Trop T) rises within hours & remains elevated for days. Results reported as neg, pos or some myocardial damage.
-CK:
At 3hrs, 25% of MIs have raised CKs
At 6hrs, 72% “ “ “ “ “
At 9hrs, 97% “ “ “ “ “
Gamma glutamyl tranferase[edit | edit source]
γGT/GTP: ♂<65 ♀<55 IU/l
↑ Liver disease esp. Cholestasis, alcoholic liver disease, cirrhosis, hepatitis
Amylase[edit | edit source]
Amy: <100 IU/l
↑ Acute pancreatitis
other abdo disorders, RF
Thyroid diseases
[edit | edit source]
Hyperthyroidism (Graves disease, multinodular goitre, adenoma) – weight loss, sweating, palpitation, angina, tremor, diarrhea, muscle weakness, goitre, eyelid retraction.
Hypothyroidism (Hashimotos disease, post surgery, congenital, secondary to pituitary/hypothalamic disease)
- lethargy, cold intolerance, dry coarse skin & hair, hoarseness, wt gain, slow reflexes & muscle relaxation. Others including: anaemia, psychosis, constipation bradycardia, CTS, infertility.
Thyroid Function Testing:[edit | edit source]
TSH 0.3-5mU/l
>15mU/l - 1° hypothyroidism
0.3-5mU/l - euthyroid (normal)
<0.3mU/l - Further investigations!
Interpretation complicated by:
-Many medications, hormones
-Any acute illness – “sick euthyroidism” all thyroid tests are low.
-Recovery – TSH raised.
Glucose:[edit | edit source]
Fasting 3-5.5 mmol/l
>7.8 – diagnostic of DM
5.5-7.8 – impaired glucose tolerance
Hyperglycaemia
[edit | edit source]
Thirst, polyuria, dehydration, hypotension, tachycardia, drowsiness.
(and for IDDM, DKA) ketosis, hyperventilation, vomiting.
Hypoglycaemia
[edit | edit source]
Tiredness, confusion, detachment, ataxia, blurred vision, dizziness, paraesthesia, hemiparesis, convulsions, coma
Lactate[edit | edit source]
<2.0 mmol/l
↑ mainly due to tissue hypoxia (decreased perfusion or decr. PO2)
Proteins
[edit | edit source]
Albumin[edit | edit source]
alb: 36-50 g/l
– Maintains oncotic pressure (keeps fluid in vessels)
- Transports small drugs, calcium & hormones
↓ (Many causes incl. malnutrition, liver disease, overhydration, incr. cap. Permeability, protein losing states, burns, haemorrhage, general catabolism-sepsis, fever, malignancy, trauma)
Symptoms – oedema! (Unresponsive to diuretics or elevation)
C-reactive protein[edit | edit source]
CRP: <5mg/l
An ‘acute phase’ protein
-Monitoring infections (>100, more likely to be bacterial)
-Distinguishing between AI diseases and active infection
-Monitoring RA Rx
-Checking for post-op infection
More sensitive than ESR
Uric acid/Urate[edit | edit source]
0.1-0.4 mmol/l
Incr. production/decr. Excretion → gout (exquisite pain and inflammation often in 1st MTP joint)
>0.54 mM → 50% chance of developing gout
Tumour Markers
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-Chemicals related to the presence/progress of a tumour
-Either secreted by tumours or cell surface antigens
-Of greater prognostic than diagnostic use, should always be interpreted in the light of clinical and other diagnostic findings.
Carcinoembryonic Antigen[edit | edit source]
CEA 2-5μg/l
-Monitoring/detection of colorectal, gastric, breast, bronchial, bronchial and some ovarian cancers.
-Modestly elevated levels in a variety of non-malignancies
Alpha Fetoprotein[edit | edit source]
AFP <9 KU/l
-Monitoring/detecting liver cancers, testicular cancer.
-Also raised in pregnancy, hepatic regeneration.
Human Chorionic Gonadotrophin[edit | edit source]
βHCG <5IU/l
-Diagnosis and monitoring of choriocarcinoma, also testicular tumours.
-Also used to detect ectopic pregnancies.
Prosate Specific Antigen (PSA)
[edit | edit source]
-Monitoring/detecting prostate cancer
-May be raised in benign prostatic hypertrophy
CA 125[edit | edit source]
<35 IU/l
-96% of patients with ovarian cancer have raised levels
CA 19-9[edit | edit source]
<60 IU/l
-Elevated in patients with pancreatic tumours
CA15-3
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-Elevated in 70% of patients with metastatic breast cancer. A good marker for monitoring Rx.
Paraproteins
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-Elevated in 98% of patients with myeloma (and other malignancies of B-cells.
-Myeloma is a haematological malignancy the symptoms of which are anaemia, bone pain (esp LBP) and pathological #s.
Immunology
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Auto-immune profile:
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Anti-nuclear antibody (ANA)
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Associated with “connective tissue disease” positive in 95% of SLE, also found in JCA, Sjogren’s syndrome, fibrosing alveolitis
Anti-mitochondrial antibodies (AMA)
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positive in >95% of primary biliary cirrhosis.
Anti-smooth muscle antibodies (ASMA)
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Positive in 50-70% of autoimmune “lupoid” hepatitis
Rheumatoid factor (RF)
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(anti-IgG antibodies) Positive in 70% of RA (but lots of false positives). Should only be used to screen, NOT monitor, (use C-RP instead)
Anti-Reticulin Antibodies.
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-Present in Coeliac disease. Also Crohns and UC.
Others:
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Anti-acetylcholine receptor antibody
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Positive in 80-95% MG
Anti-cardiolipin antibody
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Anti-phospholipid syndrome (recurrent abortion, thromboses, thrombocytopaenia)
Anti-dsDNA antibody
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Strongly suggestive of SLE
Anti-ENA (extractable nuclear antigen) Antibody
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Used to classify connective tissue diseases
Anti-Intrinsic Factor antibody
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Positive in 70% of pernicious anaemia
Anti-neutrophil cytoplasmic antibody (ANCA)
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Wegener’s granulomatosis, microsopic arteritis
Anti-thyroid antibody
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95% positive in Hashimotos thyroiditis
90% positive in primary myxoedema
18% positive in Graves disease
Haematology
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Coagulation studies -Measure the clotting mechanisms, for diagnosis and extent of disorder.
Heparin
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Therapeutic administration
-DVT, PE
-MI, Unstable Angina
-Acute peripheral occlusion.
Prophylactic administration
->30 mins GA with post-op bed rest.
-High risk patients.
Pregnancy
The anticoagulant of choice for women requiring anticoagulation
Relevant side effects
-Haemorrhage
-Thrombocytopaenia
-Osteoporosis
Monitoring of Heparin
Low dose subcut. –
no laboratory control required
Continuous iv infusion or full dose subcut. –
APTT (activated partial thromboplastin time) should
be between 50-75 seconds. Caution with high values
(>100) re spontaneous bleeding.
Warfarin
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-Patients require close monitoring of INR (International Normalized Ratio).
-Target INR ranges are 2-3 for moderate anticoagulation and 3-4.5 for more intensive therapy.
-These doses may fluctuate with no clinical significance.
-Warfarin requirements may be dramatically changed by:
illness
change in diet
change in other medication
International normalized ratio (INR)
>10 Life threatening haemorrhage can occur.
>4.5 Caution re spontaneous bleeding
-Always be wary of patients with mild haemorrhage such as haematuria or epistaxis (nosebleed).
Full Blood Count (FBC)
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Red blood cell count (RBC) ♂4.5-6.5 ♀3.5-5.8
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↓anaemias, Hodgkins disease, myeloma, leukaemia, haemorrhage, SLE, rheumatic fever and chronic infection.
↑polycythaemia, renal disorders, decr. plasma vol: (severe burns, shock, vomiting)
Haemoglobin (Hb) ♂13-18 ♀12-16
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↓anaemia, hyperthyroidism, liver/kidney disease, many CAs (especially haematological) SLE
↑haemoconcentration disorders: burns, polycythaemia, COPD, CCF.
<5 can lead to MI
>20 can lead to clogging of capillaries.
White blood cell count (WBC)
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A useful guide to the severity of a disease process
Neutrophils 2.5-7.5
Lymphocytes 1-3.5
Monocytes 0.2-0.8
Eosinophils 0.04-0.4
Basophils 0.01-0.1
Neutrophilia(↑) bacterial infections, gout, uraemia, poisoning, haemorrhage, haemolysis, necrosis.
Neutropaenia(↓) bacterial infections (poor prognosis) viral infections, certain anaemias, blood cancers, anaphylactic shock.
Eosinophilia(↑) Allergic reactions, parasitic diseases, certain blood cancers, skin infections, immunodeficiency disorders.
-Other variations occur in the specific white blood cell differential count with conditions such as: anaemias, blood cancers, infections, and certain inflammatory disorders.
Platelets (150-400)[edit | edit source]
Thrombocytosis(↑) malignancies, polycythaemia, RA & other inflammatory diseases, acute infections,
Thrombocytopaenia(↓) toxic affects of drugs, esp. chemotherapy, allergies, anaemias, viral infections, post transfusion, ITP.
Caution with low values re spontaneous bleeding, and bruising.