ANAEMIA II

The thalassaemias

The thalassaemias are a heterogeneus group of inherited disorders of haemoglobin synthesis. They are characterised by a reduction in the rate of synthesis of either alpha or beta chains and are classified accordingly. Unbalanced synthesis of alpha and beta-globin chains can damage red cells.

The basic haematological abnormality is a hypochromic microcytic anaemia of variable severity. The clinical severity of any thalassaemia is proportionate to the degree of imbalance of alpha and beta-globin chain synthesis.

α-Thalassaemias:

-Hb-Barts hydrops syndrome: there is a complete absence of α-chain synthesis which is needed for fetal and adult haemoglobin, the disorder is incompatible with life and death occurs in utero.

-HbH disease: there is a moderate chronic haemolytic anaemia with splenomegaly and sometimes hepatomegaly. Severe bone changes and growth retardation are unusual.

-α-Thalassaemia traits (carrier state).

β-Thalassaemias:

-β-Thalassaemia major: the characteristic severe anaemia is caused by α-chain excess leading to ineffective erythropoiesis and haemolysis. Anaemia first becomes apparent at 3-6 months, child fails to thrive and develops hepatosplenomegaly. Compensatory expansion of the marrow spaces causes atypical facies with skull bossing and maxillary enlargement. If left untreated further complications can include repeated infections, bone fractures and leg ulcers.

Blood transfusion remains the mainstay of management, splenectomy can reduce its frequency. With such regular transfusion iron chelation is necessary to minimise iron overload (accumulation of iron damages the liver, endocrine organs and heart with death), the common regimen is subcutaneous desferrioxamine given for 5-7 days per week. Compliance may be problematic but where good there is a considerably improved life expectancy.

-Thalassaemia intermedia: the clinical features are less severe than in β-Thalassaemia major. Patients usually present later (often at 2-5 years), have relatively high haemoglobin levels, moderate bone changes and normal growth. Regular transfusion is not required.

-β-Thalassaemia trait (minor): is a symptomless clinical disorder which should not be confused with iron deficiency. Genetic counselling is required in selected patients.

Sickle cell syndromes

The sickle cell syndromes are a group of haemoglobinopathies which primarily affect the Afro-Caribbean population. The common feature of these diseases is inheritance of an abnormal haemoglobin beta-chain gene, inheritance of two of these abnormal genes leads to a serious disorder termed sickle cell anaemia.

Sickle cell anaemia (HbSS): the classic form of sickle cell syndrome is enormously variable in severity.

-Haemolytic anaemia: the haemoglobin is usually in the range 60-100g/L, the symptoms of anemia are often surprisingly mild. Intercurrent infection with parvovirus or folate deficiency can cause a sudden fall in haemoglobin ("aplastic crisis").

-Vascular-occlusive crises: acute, episodic, painful crisis are a potentially disabling feature of sickle cell anemia. They may be triggered by infection or cold. Patients complain of musculoskeletal pain, hips, shoulders and vertebrae are most affected. Attacks are generally self-limiting but infarction of bone can occur. Other organs are vulnerable to infarction; most serious neurological damage which may manifest as seizures, transient ischaemic attacks and strokes. Vaso-occlusion in infancy is responsible for the "hand-foot syndrome", a type of dactylitis damaging the small bones of hand and feet.

First line treatment is rest, increased fluids and adequate oral analgesia. Constitutional upset or pain not relieved by oral analgesia requires hospital admission with continued rest, warmth, intravenous fluids and opiate analgesia.

-Sequestration crises: these arise from sickling and infarction within particular organs. Specific syndromes include "acute chest syndrome" with occlusion of the pulmonary vasculature, "girdle sequestration" caused by occlusion of the mesenteric blood supply, and hepatic and splenic sequestration.

-other complications: papillary necrosis with haematuria, loss of ability to concentrate urine, nephrotic syndrome, priapism, lower limb ulceration, proliferative retinopathy, glaucoma, liver damage and pigment gallstones.

Management:

Prophylaxis is important, patients should avoid factors known to precipitate crisis, take folate supplements and be prescribed penicillin and pneumococcal vaccine. Infections require prompt treatment.

Treatment options are blood transfusions, hydroxycarbamide and stem cell transplantation when indicated.

Prognosis:

The risk of early death is inversely related to fetal haemoglobin levels. The most common causes of death are infection in infancy, cerebro-vascular accidents in adolescence and respiratory complications in adult life.

Sickle cell trait (HbAS): normally causes no clinical problems. However, haematuria occasionally occurs as a result of renal papillary necrosis and additional care is required during pregnancy and anaesthesia.

Sources:
-http://www.slideshare.net/giridharkv/thalassemia-drkvgiridhar
-https://www.pinterest.com/kedillard/thalassemia-awareness/
-Haematology, 3rd Edition, Martin R. Howard, Churchill Livingstone, Elsevier, 2008.
-https://www.linkedin.com/pulse/sickle-cell-disease-scd-metrohealth-hmo

-http://www.slideshare.net/sandipgupta77770194/sickle-cell-disease-sandip

ANAEMIA I

The term "anaemia" refers to haemoglobin or red cell concentration below the accepted normal range in the blood. With the widespread introduction of automated equipment into haematology laboratories the haemoglobin concentration has replaced the haematocrit as the key measurement.

The normal range for haemoglobin is affected by sex, age, ethnic group and altitude.

Normal haemoglobin (Hb) value:

-male (adult): 13 - 18 g/dL

-female (adult): 11.5 - 16 g/dL

Iron deficiency anaemia (Microcytic)

Iron is a constituent of haemoglobin and rate limiting for erythropoiesis, its metabolism is dominated by its role in haemoglobin synthesis.

Iron deficiency can usually be diagnosed with the clinical history and simple laboratory tests but, a cause for the deficiency must always be sought.

Iron deficiency can be caused by long-term blood loss (e.g. gastrointestinal or uterine bleeding), Hookworm infection, poor diet, malabsorption or increased demand for iron as in pregnancy.

Clinical features

Patients with long-standing deficiency may develop nail flattening and koilonychia (concave nails), sore tongues and papillary atrophy, angular stomatitis, dysphagia and gastritis. 

Patients may complain of heavy periods, indigestion or a change in bowel habit.

Iron deficiency in young children can contribute to psychomotor delay and behavioural problems.

Management

-Investigation of underlying cause.

-Correction of iron deficiency:
The normal regimen is oral ferrous sulphate 200mg three times a day for at least 6 months to replete body stores (side effects are best managed by reducing the dosage rather than changing the preparation). Parenteral iron (IV or IM) can be used where oral therapy is unsuccessful.

Megaloblastic anaemia 
Megaloblastic anaemia is a common cause of a macrocytic anaemia,  In clinical practice it is almost always caused by deficiency of vitamin B12 or folate.

-Vitamin B12 deficiency (Pernicious anaemia): 
The classic cause is an autoimmune disorder. Patients usually have symptoms of anaemia and the generalised epithelial abnormality can manifest as glossitis and angular stomatitis.
Patients complain of unsteady gait, and if B12 deficiency is not corrected there can be a progression to irreversible damage of the central nervous system. Also, there is a possible increased incidence of carcinoma of the stomach and colorectal cancer.
Vitamin B12 levels are usually replenished by intramuscular injection of the vitamin. Several injections of 1mg hydroxycobalamin are given over the first few weeks and then either one injection every three months or daily oral vitamin B12 1 to 2mg daily for life.
Other causes of vitamin B12 deficiency are mostly abnormalities of the stomach and ileum.

-Folate deficiency:
Folate deficiency is caused by dietary insufficiency, malabsorption, excessive utilisation or a combination of these. Patients may complain of symptoms of anaemia or of an underlying disease.
Folate deficiency is treated with oral folic acid 5mg once daily, the precise duration of therapy depends on the underlying cause.
Before folate is prescribed, vitamin B12 deficiency must be excluded (or corrected) as subacute combined degeneration of the spinal cord can be precipitated.

Haemolytic anaemia
The term "haemolytic anaemia" describes a group of anaemias of differing aetiology that are all characterised by abnormal destruction of red cells.

Classification of the haemolytic anaemias:

• Inherited disorders:

1. Disorders of the red cell membrane: hereditary spherocytosis and hereditary elliptocytosis.
-Hereditary spherocytosis: fluctuating levels of jaundice and palpable splenomegaly are common features. No treatment is required in patients with mild disease, in more serious cases the spleen is removed.

-Hereditary elliptocytosis: has many similarities to hereditary spherocytosis, splenectomy helps in the rare severe cases.

2. Abnormalities of haemoglobin: thalassaemia syndromes and sickling disorders.

3. Abnormalities of red cell metabolism: glucose-6-phosphate dehydrogenase and pyruvate kinase deficiency.
-Glucose-6-phosphate (G6PD) dehydrogenase: common triggers are fava beans, drugs and infections. Treatment is to stop any offending drug and to support the patient, blood transfusion may be necessary.
-Pyruvate kinase (PK) deficiency: all general features of haemolysis can be present, but clinical symptoms are often mild for the degree of anaemia. Splenectomy may help in reducing transfusion requirements.

• Acquired disorders:

1. Immune: warm and cold autoimmune haemolytic anaemia.
This disease can be divided into "warm" and "cold" types depending on the temperature at which the antibody reacts optimally with red cells.

-Warm autoimmune haemolytic anaemia (Warm AIHA): is the most common form of the disease, appoximately half of the cases are idiopathic but in the other half there is an apparent underlying cause e.g. lymphoproliferative disorders, other neoplasms, connective tissue disorders, drugs or infections.
Splenomegaly is a frequent examination finding in severe cases.
Management: identification and treatment of the cause, stop any offending drugs (e.g cephalosporin antibiotics), where the haemolysis itself requires treatment, steroids are normally used. Splenectomy is usually indicated when steroid resistance is present.

-Cold autoimmune haemolytic anaemia (Cold AIHA): the cause can be cold haemagglutinin disease, lymphoproliferative disorders, infections or paroxysmal cold haemoglobinuria.
Circularoty problems such as acrocyanosis, Raynaud´s phenomenon and ulceration may be present,  haemoglobinuria may occur when red cell destruction is intravascular.
Where the Cold AIHA is chronic the mainstay of treatment is keeping the patient warm, especially in the extremities. In forms associated with lymphoproliferative disorders, cytotoxic drugs or rituximab may be helpful.

2. Isoimmune: rhesus or ABO incompatibility.

3. Non-immune and trauma: valve prostheses, microangiopathy, infection, drugs or chemicals and hypersplenism.
-Microangiopathic haemolytic anaemia (MAHA): is the intravascular destruction of red cells in the presence of an abnormal microcirculation. Common triggers are the presence of disseminated intravascular coagulation (DIC), abnormal platelet aggregation and vasculitis.
Clinical syndromes associated with MAHA include haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP).

Sources:

-https://themedicalpost.wordpress.com/2010/07/18/the-general-concept-of-anaemias/
-Haematology, 3rd Edition, Martin R. Howard, Churchill Livingstone, Elsevier, 2008.
-http://justinhealth.com/symptoms-of-anemia/
-http://www.spinabifida.net/cobalamin-vitamin-b12-folic-acid-deficiency-in-spina-bifida-neural-tube-defects.html
-http://www.thecambodiaherald.com/health/splenomegaly-%E2%80%93-symptoms-and-causes-688
-http://health.kernan.org/patiented/articles/000541.htm

VENEPUNCTURE AND CANNULATION

BLOOD TESTS

The primary duty of the phlebotomist is to collect blood specimens for laboratory testing, this task is also performed by nurses and doctors.

Blood tests are performed for diagnostic purposes and monitor treatment, they are collected by several methods, including arterial puncture, capillary puncture and venipuncture.

Clinical laboratory services:

-Hematology: performs laboratory tests that identify diseases associated with blood and the blood-forming tissues.

-Coagulation: is the study of the ability of blood to form and dissolve clots.

-Chemistry: performs most laboratory tests and often has subsections such as toxicology and radioimmunoassay.

-Serology or Immunology:serology tests deal with the body´s response to the presence of bacterial, viral, fungal or parasitic diseases stimulating antigen-antibody reactions.

-Urinalysis: physical and chemical evaluation of urine specimens.

-Microbiology: analyzes body fluids and tissues for the presence of microorganisms, primarily by means of culture and sensitivity.

-Blood bank or Immunohematology: prepares blood products to be used for patient transfusions.

Venipuncture

Venipuncture is the process of collecting or "drawing" blood from a vein and the most common way to collect blood specimens for laboratory testing.

Common test status designations:

-Stat: immediately (from Latin statim).

-Med Emerg: medical emergency (replaces stat).

-Timed: collect at a specific time.

-ASAP: as soon as possible.

-Fasting: no food or drink except water for 8-12 hours prior to specimen collection.

-NBM, NPO: nil by mouth (from Latin nil per os).

-Preop: before an operation.

-Postop: after an operation.

-Routine: relating to established procedure.

Order of draw refers to the order in which tubes are collected during a multiple-tube draw or are filled from a syringe. CLSI (Clinical and Laboratory Standards Institute)* recommends the following order of draw for both ETS (evacuated tube system) collection and in filling tubes with a syringe:

1. Sterile tube (blood culture).

2. Blue-top coagulation tube.

3. Serum tube with or without clot activator, with or without gel.

4. Heparin tube with or without gel plasma separator.

5. EDTA tube.

6. Glycolytic inhibitor tube.

Capillary puncture

Capillary puncture can be an appropiate choice for adults and older children under the following circumstances:

-available veins are fragile or must be saved for other procedures such as chemotherapy,

-several unsuccessful venipunctures have been performed and the requested test can be collected by capillary puncture,

-the patient has thrombotic or clot-forming tendencies,

-the patient is apprehensive or has an intense fear of needles,

-there are no accessible veins,

-to obtain blood for POCT (Point-Of-Care Testing) procedures such as glucose monitoring.

Capillary puncture is the preferred method of obtaining blood from infants and very young children. The heel is the recommended site for collection of capillary puncture specimens on infants less than 1 year of age.

The CLSI order of draw for capillary specimens is as follows:

1. Blood gas specimens (CBGs)

2. EDTA specimens

3. Other additive specimens

4. Serum specimens.

Arterial puncture

Arterial puncture is technically difficult and potentially more painful and hazardous than venipuncture. The primary reason for arterial puncture is to obtain blood for arterial blood gas (ABG) tests, which evaluate respiratory function.

ABG evaluation is used in the diagnosis and management of respiratory disorders such as lung disease to provide information about a patient´s oxygenation, ventilation, acid-base balance and in the management of electrolyte and acid-base balance in patients with diabetes and other metabolic disorders.

Laboratory tests

Laboratory Tests

Leer más publicaciones en Calaméo

*Organizations similar to CLSI but in the United Kingdom and another clinical laboratory information site:

-http://www.acb.org.uk/whatweare.aspx

-http://labtestsonline.org.uk/

Source:
-Phlebotomy Essential, 5th Edition, Ruth E. McCall, Cathee M. Tankersley, Wolters Kluwer/ Lippincott Williams & Wilkins, 2012.
-http://clsi.org/.
-http://www.healthaw.com/userfiles/image/Blood%20Collection.jpg
-http://i.ytimg.com/vi/YuFK22n-tvI/hqdefault.jpg