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Filename: CB-INF-HAEMATINICS, Version: 2. Date of issue: September 2021
Contents
VITAMIN B12 .........................................................................................................................................................................................................................................................................
FOLATE...................................................................................................................................................................................................................................................................................
FERRITIN ................................................................................................................................................................................................................................................................................
Guidance for Primary Care on the
Interpretation of Haematinics
B12, Folate and Ferritin
Department of Clinical Biochemistry
Filename: CB-INF-HAEMATINICS, version 2. Date of issue: Sep Page 1 of 3
Vitamin B
B12 deficiency does not usually require secondary care referral.
Replacement is usually given by IM injection. Oral replacement may be appropriate for mild deficiencies where the IFA result is negative.
It is not appropriate to measure B12 in patients on IM treatment. Monitor response to treatment using the full blood count (Hb and MCV).
Clinical features of B12 deficiency B12 levels are not easily correlated with clinical features, and low levels may not represent a functional B12 deficiency.
Features of B12 deficiency may include: Macrocytic anaemia (MCV >101 fl)* Glossitis Paraesthesia, unsteadiness, peripheral neuropathy *Note co-existing iron deficiency/thalassaemia trait may mask macrocytosis
Causes of B12 deficiency
Pregnancy, OCP, HRT (not thought to represent a functional B12 deficiency) Medications : metformin, PPI, anti-convulsants e.g. phenytoin, antibiotics, colchicine Vegetarian/vegan/poor diet Malabsorption – consider other features of malabsorption/pancreatic insufficiency Pernicious anaemia – consider history of autoimmune disease and/or family history Folate deficiency Parasitic infection, HIV,
Probable/Mild B12 deficiency. ? symptoms/clinical features
B12 197 – 771 ng/L
B12 deficiency unlikely.
If strong clinical suspicion remains, consider a trial of replacement especially if B12 result borderline
B12 150 – 196 ng/L
Commence replacement. Consider possible underlying causes Request intrinsic factor antibodies (IFA)
Repeat in 6 – 8 weeks If B12 still low, consider replacement and measure intrinsic factor antibodies (IFA)
B12 <150 ng/L
B12 deficiency highly likely.
Confirm with clinical findings
Commence replacement (IM)
Intrinsic factor antibodies (IFA)
will be added by laboratory
Consider underlying cause
Yes No
B12 >771 ng/L
High B12 in patients not on treatment may be due to consumption of OTC supplements or fortified food. It can also be associated with the following conditions:
Myeloproliferative disorders (unlikely if FBC normal) Liver disease Renal failure Please contact the Duty Biochemist if you wish to discuss further.
Filename: CB-INF-HAEMATINICS, version 2. Date of issue: Sep Page 3 of 3
Ferritin
For investigation of iron deficiency, serum ferritin is the recommended front line test and is superior to transferrin saturation.
Monitor response to iron therapy using FBC (Hb and MCV) initially. There is no need to re-check ferritin levels within 6 – 8 weeks.
<15 μg/L
Iron deficiency confirmed.
Evaluate underlying cause and commence replacement.
15 – 30 μg/L
Iron deficiency likely.
Consider clinical context and commence replacement if appropriate. Evaluate underlying cause
30 – 150 μg/L
Iron deficiency unlikely.
CRP <5 mg/L?
Iron deficiency not excluded. Transferrin saturation will be added by laboratory
For patients with chronic inflammatory conditions, interpret ferritin cautiously. Ferritin levels are increased independently of iron status in acute and chronic inflammatory conditions, malignancy and liver disease which may mask deficiencies. Review FBC parameters and transferrin saturation; if <16%, iron deficiency is possible. Note: transferrin saturation is non-specific as pregnancy, OCP and chronic illness can result in low transferrin saturation without iron deficiency.
Yes No
1 50 μg/L
Iron deficiency unlikely
If Ferritin elevated above age and sex reference ranges and CRP normal Refer to https://tinyurl.com/BiochemInfo for investigation of hyperferritinaemia.
Causes of iron deficiency
Inadequate diet or malabsorption Bleeding , e.g. GI bleeding, menorrhagia or blood donation Chronic renal failure and haemodialysis Infancy, pregnancy or lactation Increased red cell turnover
Clinical features of iron deficiency Features of iron deficiency include: Microcytic hypochromic anaemia (MCV <79 fl) Symptoms of anaemia – fatigue, dyspnoea, pallor. Symptoms of iron deficiency may occur without anaemia: lack of concentration, irritability, hair loss, dry skin, angular cheilosis, atrophic glossitis, spoon-shaped nails, and unusual cravings for non-food items (phenomenon known as pica).
