Iron deficiency Flashcards
Major food sources of iron (and why)
Foods of animal origin
Have high bioavailability (iron from plants = low solubility and have chelators that prevent absorption)
Where is iron absorbed?
Duodenum by enterocytes
Most of the iron in the body is in the form of…?
Circulating haemoglobin
How can iron be absorbed by enterocytes?
As an ion (Fe2+)
As part of a protein e.g. haem
Their brush border has a ferric reductase enzyme that can reduce Fe3+ to Fe2+.
What enhances iron absorption?
Acid pH, iron deficiency, pregnancy, and hypoxia
What are transferrins?
Iron-binding plasma glycoproteins that control the level of free iron in plasma
Each molecule has the ability to carry two Fe3+ atoms.
How is iron transported from enterocytes to inside the cell?
Iron is taken up from enterocytes by transferrin and transported in the blood to the bone marrow and other cells. This then binds to a transferrin receptor on the surface of the cell and is transported into the cell by endocytosis.
Inside the cell, how is iron released and stored?
Inside the cell, transferrin releases the ions and they are taken up by ferritin (a large hollow globular protein) and stored inside. The receptor/transferrin complex is transported back to the cell surface/release ready for another round.
What is ferritin and what is it’s role?
Ferritin releases iron in a controlled fashion when needed, acting as a buffer. It is a cytosolic protein but small amounts are secreted into the serum where it functions as an iron carrier.
Define iron deficiency anaemia
Diminished red blood cell production due to low iron stores in the body
What does iron deficiency anaemia show on blood film?
Microcytic, hypochromic cells
Define anaemia using Hb level for men over 15 years old
Below 130 g/L
Define anaemia using Hb level for women over 15 years old AND children age 12-14
Below 120 g/L
Define anaemia using Hb level for pregnant women
Below 110 g/L
Define anaemia using Hb level for postpartum women
Below 100 g/L
A serum ferritin level of less than (blank) confirms iron deficiency
15 micrograms/L
Causes of iron deficiency anaemia
Dietary deficiency (rarely a cause on its own)
Malabsorption (e.g. coeliac disease, gastrectomy, or H pylori, IBD, hookworm)
Increased loss e.g. menstruation, gastric ulcers, varices, GI cancers, NSAIDs, blood donation, self-harm, haematuria, nosebleeds
Increased requirement e.g. pregnancy, growth
Most common cause of iron deficiency anaemia in pre-menopausal women
Menstruation
Most common cause of iron deficiency anaemia in men and pre-menopausal women
GI blood loss
Complications of iron deficiency anaemia
Cognitive and behavioural impairment in children
Impaired muscular performance
Heart failure
Adverse effects on immunity
What to ask in history?
PC/HPC - symptoms of anaemia (including angina, palpitations, ankle swelling)
ROS - GI bleeding, weight loss, fever, fatigue, change in bowel habit
PMH - overt bleeding, heavy bruising, blood donation, recent illness/surgery
Obs history - menstrual, pregnancy, breastfeeding
DH - NSAIDs, aspirin, SSRIs, clopidogrel, corticosteroids
FH - iron def anaemia, bleeding disorders and telangiectasia, colorectal carcinoma, haematological disorders
SH - diet, travel
Symptoms of iron def anaemia
Dyspnoea Fatigue Headache Cognitive dysfunction Restless leg syndrome Vertigo
Rare symptoms - dysphagia (from post-cricoid webs), haemodynamic instability, syncope
Other symptoms - dizziness, weakness, irritability, palpitations, pica, pruritus, sore tongue, tinnitus, impairment of body temperature regulation
Angina, ankle oedema, dyspnoea at rest unlikely unless Hb <70
Signs of iron def anaemia
Pallor Atrophic glossitis Dry and rough skin, dry and damaged hair Diffuse and moderate alopecia Angular cheilosis Nail changes e.g. longitudinal ridging and koilonychia
Tachycardia, murmurs, cardiac enlargement, and heart failure may occur if severe
Signs and symptoms of hookworm infection
Cutaneous larva migrans, itchy rash, cough and wheeze a few weeks after exposure, abdominal pain, diarrhoea, anorexia, weight loss, fatigue.
Signs and symptoms of coeliac disease
Diarrhoea, abdominal pain, bloating and flatulence, indigestion, constipation, fatigue, weight loss, dermatitis herpetiformis, infertility, peripheral neuropathy, ataxia, delayed puberty.
Signs and symptoms of inflammatory bowel disease
Abdominal pain/cramps, diarrhoea, weight loss, fatigue. Remission and flare-ups.
Signs and symptoms of GI cancer
Change in bowel habit, abdominal pain, blood in the stools, bloating, weight loss
Signs and symptoms of ulcer
Indigestion, abdo pain
Bloods to confirm suspected iron def anaemia
FBC - Hb, MCV
Ferritin
Consider testing vitamin B12 and folate
Define microcytosis
Mean cell volume (MCV) less than 80 femtolitres
Red blood cell changes associated with iron def
Hypochromia
Anisocytosis (variation in size of RBCs)
Poikilocytosis (irregular shaped RBCs)
May have pencil cells
Investigations for all people with confirmed iron deficiency anaemia
Screen for coeliac disease (anti-tissue transglutaminase antibodies)
Test the urine for blood.
Consider stool examination to detect parasites (if appropriate)
Consider others where appropriate
Differentials for iron def anaemia
Thalassaemia - MCV and MCH reduced, very low for degree of anaemia, increase in serum iron and ferritin, low total iron-binding capacity, target cells, DNA analysis/Hb electrophoresis for definitive diagnosis
Sideroblastic anaemias (very rare) - can be due to alcoholism, hepatosplenomegaly, increase in serum iron and ferritin, low total iron-binding capacity, sideroblasts in marrow
Anaemia of chronic disease - usually normocytic and normochromic
Lead poisoning (rare in adults) - history of risk factors
Management
Address underlying causes and refer where appropriate
Advise the person to maintain an adequate balanced intake of iron-rich foods
Oral ferrous sulfate 200 mg tablets two or three times a day — treatment should continue for 3 months after iron deficiency is corrected
Monitor 2-4 weeks, check again after 2-4 months, then every 3 months for 1 year, recheck again after another year
What if ferrous sulfate is not tolerated?
Consider oral ferrous fumarate tablets or ferrous gluconate tablets.
Side effects of ferrous sulphate
Constipation; diarrhoea; gastrointestinal discomfort; nausea
How to reduce side effects of ferrous sulphate
Take with food
Can take lower doses e.g. twice a day instead of TDS
Swap to ferrous gluconate or fumarate
S/Es usually settle down with time
When should ongoing prophylactic dose of iron be considered?
Recurring anaemia and further investigations are not indicated or appropriate. An iron-poor diet Malabsorption Menorrhagia Had a gastrectomy Women who are pregnant. People undergoing haemodialysis
