deficiency anaemias Flashcards
nutrients important to erythropoiesis
B12
folate
iron
causes of iron deficiency
poor diet - vegans, vegetarians, elderly, eating disorder
malabsorption - coeliac disease, gastrectomy, atrophic gastritis
chronic blood loss:
- reproductive
- gi tract (peptic ulcers, IBS…)
- genitourinary (haematuria)
- resp - haemoptysis
physiological - pregnancy, adolescent growth spurt
Investigations to confirm iron deficiency (characteristic findings)
Full blood count: Anaemia MCV LOW MCH(C) LOW Thrombocytosis
Blood film: Microcytosis Hypochromia (pale centre or bullseye) Pencil cells Target cells
Iron studies: serum iron LOW TIBC RAISED Serum ferritin LOW Transferrin saturation LOW
Bone marrow (Perl’s stain):
Absent stainable iron
Rarely required
May be useful if iron studies affected by inflammation
Investigations to determine underlying cause of iron def anaemia
Dietary and menstrual history
May be clear cut
Endoscopy and/or colonoscopy
If GI symptoms or iron deficiency unexplained
Actively look for cancer in older patients
Coeliac screen
Anti-tissue transglutaminase
Duodenal biopsy
Stool for ova, cysts and parasites
If positive travel history
DD of iron def anaemia
The thalassaemia syndromes
Request haemoglobinopathy screen
Raised HbA2 indicates -thalassaemia trait
Iron studies normal unless co-existing iron deficiency
Note ethnicity of patient
Anaemia of chronic disease Clinical history Usually normocytic normochromic, but may be microcytic (MCV low, TIBC low) Raised inflammatory markers Ferritin normal or raised
Sideroblastic anaemia
Iron deficiency – treatment
Replace iron
Oral: ferrous sulphate 200mg tds for 3-4 months
Parenteral: Hb response same as for oral
Blood transfusion only rarely required
Treat underlying cause
Failure of response Non-compliance Incorrect diagnosis eg. thalassaemia trait Malabsorption Ongoing bleeding Other haematinic deficiencies
Vitamin B12
Found in foods of animal origin (including dairy products)
Stored in liver (3-4mg)
Dietary deficiency develops over 3-4 years
Absorption:
Intact stomach – gastric parietal cells produce intrinsic factor
Terminal ileum is site of absorption
causes of vitamin B12 deficiency
dietary intake - vegans malabsorption : - autoimmune (pernicious anaemia) - Gi tract problems - crowns, resection of terminal ileum. - lifestyle - alcoholism - drugs - metformin - parasites - fish tapeworm
metabolic inhibition - NO
B12 deficiency – clinical presentation
Effects on bone marrow
Megaloblastic anaemia
Neutropenia and/or thrombocytopenia
Effects on gut epithelium
Atrophic glossitis
angular stomatitis
Effects on neural tissue Peripheral neuropathy Myelopathy (subacute combined degeneration of cord) Optic atrophy Neurocognitive – eg. dementia Neuropsychiatric eg. depression
B12 deficiency – history
Symptoms of anaemia Tiredness Shortness of breath on exertion Reduced exercise tolerance Light headedness etc
Symptoms of tissue deficiency
Painful glossitis
Neurological complications
Dietary history
Vegan?
Personal or family history of autoimmunity
eg. autoimmune thyroid disease
Any family member on vitamin injections?
B12 deficiency - investigations
Full blood count: Anaemia Raised MCV Raised MCH(C) Neutropenia Thrombocytopenia
Blood film:
Oval macrocytes
Hypersegmented neutrophils
Biochemistry:
Mild increase in bilirubin
Increased LDH
Diagnostic investigations:
Low serum B12
GPC and IF antibodies positive in PA
Bone marrow - megaloblastic changes
Schilling test - Correction of B12 malabsorption by IF in PA
- Non correction in terminal ileal disease and bacterial overgrowth
B12 deficiency - treatment
Replace B12
hydroxocobalamin 1mg i.m. x6 over 2 weeks
Maintain with 3-monthly injections if malabsorption
May need to give folic acid and iron supplements in severe B12 deficiency anaemia
Note:
Never give folic acid on its own to B12 deficient patient – risk of neurological complication
Folate
Dietary folate mostly in form of polyglutamates
Wide variety of sources including: leafy green vegetables (eg. spinach) liver fruits beans wheatgerm yeast etc
Converted to monoglutamates before absorption
Absorbed from duodenum and jejunum
Main storage organ is liver (50% of body stores)
causes of folate deficiency
diet - old age, poverty
malabsorption - coeliac disease, crown’s, small bowel resection
increased utilisation:
- physiological - pregnancy, prematurity
- pathological - chronic haemolytic anaemia, myelofibrosis. malignancy - carcinoma, leukaemia etc. inflammatory conditiosn - severe psoriasis, crohn’s
drugs - induced malabsorption - anticonvulsants. others
excessive urinary loss - congestive heart failure
misc - liver disease, alcoholism
Folate deficiency - features
Clinically and haematologically indistinguishable from B12 deficiency
Neurological complications
- Neural tube defects
- Others less prevalent than with B12 deficiency
Deficiency state can develop within weeks to months
