CLASSIFICATION AND GENERAL FEATURES OF ANAEMIA Flashcards
What is the definition of anaemia?
A reduction in concentration of circulating haemoglobin or oxygen carrying capacity of blood below the level that is expected for healthy persons of same age and sex in the same environment
IT IS NOT A DIAGNOSIS
WHO definition (Adults): Haemoglobin (Hb) concentration < _____/dl in males, <_____g/dl in females
< 13g/dl in males
<12g/dl in females
Anemic Hb concentration in Africa
10 g/dl
What are reference ranges?
•Also called reference interval.
•Range of values deemed normal for a physiologic measurement in healthy persons.
•Derived from apparently healthy persons in a given population.
•It takes into account age, sex and geographical location (environment).
•Values within the reference range are described as “within normal limits”.
How are reference ranges derived?
•Samples are taken from an apparently healthy population
•The values obtained are computed
•Normal distribution of the measured parameters are assumed.
•The mean is calculated
•2 standard deviations (SD) on either side of the mean are also obtained.
•± 2 SD on either side of the mean encompasses 95% of the general population
What is reference range statistically?
Statistically, reference range of a particular measurement is the interval between which 95% of values of a reference population fall into.
Discuss the limits of the reference range
•It has two limits:
•MEAN – 2 S.D = Lower reference limit
•MEAN – 2 S.D = Upper reference limit
•Values within the reference range are described as “within normal limits”
•Values below the lower limit of normal are described as “low”
•Values above the upper limit of normal are described as “high”
Types of Classification of anaemia
•Aetiology: based on cause
•Morphology: based on red cell indices
• based on presence or absence of clinical features
• Severity: based on PCV levels
Classification based on aetiology
-impaired red cell production
-excessive red cell destruction (haemolytic anaemias)
-excess blood loss
Classification based on morphology
-Macrocytic
-Microcytic
-Normocytic
Classification based on presence or absence of clinical features
-speed of onset
-age
-hemoglobin O2 dissociation curve
Classification based on severity
-Mild (>27.1 - 29.9%)
-Moderate (21.1 - 27%)
-Severe (<21%)
Symptoms (History)
*Shortness of breath (dyspnea), usually on exertion
*Easy fatiguability
*Body weakness
*Palpitations
*Headache
*Dizziness
*Lethargy
Specific symptoms would be treated under specific anaemias
Signs of anaemia
Signs (Physical examination)
*Pallor (check conjunctiva)
*Jaundice (+/-) (check sclera)
*Tachycardia
*Full volume, bounding pulse
*Displaced apex beat indicative of cardiomegaly (+/-)
*Third heart sound, S3 (+/-)
*Pan-systolic murmur
NB: Specific signs would be treated under specific anaemias
Investigations
*Full blood count and differentials
*Red cell indices
*Reticulocyte count
*Blood film
*Haemoglobin electrophoresis
*Coombs Test (Antiglobulin test) (to know if the anemia os as a result of autoimmune disease)
*Bone marrow aspiration and biopsy
*Iron studies (to determine iron deficiency anemia)
*Vitamin B12/ folate assays (to determine megaloblastic anemia)
*Enzyme assays
Serum bilirubin
