7.1 Haematology
Key Takeaways
- Iron-deficiency anaemia is the most common cause in UK dental patients and typically presents with mucosal pallor, angular cheilitis and aphthous-like ulceration; a full blood count (FBC) is the first-line investigation when the history suggests anaemia
- A platelet count of at least 50 x10^9/L is generally considered safe for straightforward dental extractions in the UK; below 50 x10^9/L the haematology team must be consulted, and some centres use higher thresholds (~75-80 x10^9/L) for multiple or complex surgical extractions
- Sickle cell disease has no contraindication to local anaesthetic with epinephrine, but appointments should be short, early-morning and avoid hypoxia, dehydration, acidosis and hypothermia; general anaesthesia is hazardous and must be in hospital with haematology support
- Acute myeloid leukaemia (particularly monocytic variants M4/M5) can present with gingival hypertrophy from leukaemic infiltration, while thrombocytopenia from any cause produces spontaneous oral petechiae and ecchymoses
- Multiple myeloma may present with punched-out jaw radiolucencies, hypercalcaemia-related symptoms and amyloid deposition in the macroglossic tongue; check FBC, calcium and renal function before invasive treatment
The Anaemias
Anaemia is a reduction in haemoglobin concentration below the reference range for age and sex. It is the most common haematological problem encountered in dental practice and is relevant because tissue oxygenation underpins healing, mucosal integrity and infection resistance.
Classification by Red Cell Size
| MCV category | Common causes | Oral features |
|---|---|---|
| Microcytic (MCV <80 fL) | Iron deficiency, thalassaemia trait | Mucosal pallor, angular cheilitis, aphthous-like ulcers |
| Normocytic (80-100 fL) | Acute blood loss, anaemia of chronic disease, renal failure | Pallor, delayed healing |
| Macrocytic (MCV >100 fL) | Vitamin B12 deficiency (pernicious), folate deficiency, liver disease, alcohol | Glossitis (smooth red tongue), aphthous ulcers, angular cheilitis |
Iron-Deficiency Anaemia
The most common cause in UK adults is chronic gastrointestinal blood loss; in pre-menopausal women, menstrual loss dominates. Oral features include generalised mucosal pallor, angular cheilitis, aphthous-like ulceration and, rarely, Plummer-Vinson syndrome (iron deficiency with oesophageal web and increased oral/oropharyngeal cancer risk). A FBC shows low haemoglobin, low MCV and low ferritin.
Pernicious Anaemia (B12)
Pernicious anaemia is an autoimmune destruction of gastric parietal cells leading to intrinsic factor deficiency and vitamin B12 malabsorption. It causes a megaloblastic, macrocytic anaemia and may produce neurological sequelae (subacute combined degeneration of the cord). Oral signs include a smooth, beefy-red, painful glossitis and recurrent aphthae. B12 is given intramuscularly as hydroxocobalamin; dental treatment is deferred until the count has stabilised if the anaemia is severe.
Sickle Cell Disease and Thalassaemia
Sickle cell disease (SCD) is an autosomal recessive haemoglobinopathy (HbSS) common in people of African and Caribbean heritage. Under hypoxia, acidic or dehydrated conditions, red cells sickle, causing vaso-occlusion. A painful sickle crisis can be precipitated by infection, dehydration, hypoxia, acidosis, hypothermia and stress.
Dental management of SCD:
- Treat only in non-crisis periods; during a crisis manage pain and infection only.
- Local anaesthetic with epinephrine is not contraindicated; aspirate to avoid intravascular injection.
- Appointments: short, early-morning, avoid prolonged fasting.
- Avoid aspirin and NSAIDs (renal papillary necrosis risk and acidosis); use paracetamol or codeine.
- General anaesthesia is hazardous - refer to hospital with haematology support; pre-oxygenate, maintain normothermia, hydration and oxygenation.
- Aggressive prevention to avert odontogenic infection, a recognised crisis trigger.
Thalassaemia produces a microcytic anaemia from globin chain imbalance; transfusion-dependent majors risk iron overload (hepatic, cardiac, endocrine) and need a FBC and ferritin review before surgery.
Leukaemia, Lymphoma and Myeloma
Leukaemia
Leukaemia is a clonal malignancy of haematopoietic cells. Acute forms (acute myeloid leukaemia, AML; acute lymphoblastic leukaemia, ALL) present abruptly; chronic forms (CML, CLL) are often incidental findings.
Oral and dental relevance:
- Gingival hypertrophy from leukaemic infiltration - classical in AML monocytic variants (M4/M5).
- Spontaneous petechiae, ecchymoses, gingival bleeding from thrombocytopenia.
- Aphthous-like ulcers, mucosal pallor and secondary candidiasis or herpetic infection from neutropenia.
- Delayed healing and infection after extractions.
For patients on active chemotherapy, dental work should ideally be completed before treatment starts; during chemotherapy, only urgent care is provided and blood counts must be checked (often require neutrophils >1.5 x10^9/L and platelets >50 x10^9/L - liaise with the haematology team).
Lymphoma
Hodgkin lymphoma (Reed-Sternberg cells, B symptoms) and non-Hodgkin lymphoma may produce cervical lymphadenopathy. Intra-oral involvement is rare but possible (palatal swelling, non-healing ulcer). Biopsy suspicious persistent (>2-3 weeks) ulceration.
Multiple Myeloma
A plasma cell neoplasm producing a monoclonal protein (M band) and osteolytic punched-out bone lesions - classically in the skull and jaws. Features relevant to dentistry:
- Radiolucencies in the jaws (may mimic periapical pathology - confirm vitality before extraction).
- Hypercalcaemia (thirst, confusion, constipation).
- Amyloidosis - macroglossia with crenations.
- Renal impairment from light chain cast nephropathy - adjust drug dosing.
- Bleeding tendency from thrombocytopenia and acquired platelet dysfunction.
Platelet Disorders and Polycythaemia
Thrombocytopenia
A platelet count below 150 x10^9/L. Causes include immune thrombocytopenia (ITP), leukaemia, drug-induced, heparin-induced, and hypersplenism. Oral signs - petechiae on the palate or buccal mucosa, gingival bleeding, prolonged post-extraction ooze.
UK dental thresholds (consensus of NICE NG24, BSH and SDCEP anticoagulant guidance):
| Platelet count | Dental action |
|---|---|
| >=50 x10^9/L (with low bleeding-risk score) | Generally safe for straightforward extractions in primary care with local measures |
| <50 x10^9/L | Consult haematology before any invasive treatment; consider platelet transfusion to raise above 50 |
| Complex / multiple surgical extractions | Some centres use a higher threshold (~75-80 x10^9/L); liaise with the local team |
| >=30 x10^9/L | British Society for Haematology suggests minor surgery may be undertaken, but this is not routinely applied in primary dental care |
Local haemostatic measures (sutures, oxidised cellulose, tranexamic acid 4.8% mouthwash) are the mainstay of post-extraction bleeding control; antifibrinolytics should not be used in patients with a history of thromboembolism.
Polycythaemia
Polycythaemia vera is a myeloproliferative neoplasm with increased red cell mass and a thrombotic tendency. Patients are at increased risk of arterial and venous thrombosis; venesection and low-dose aspirin are typical management. Dental relevance - bleeding on anticoagulants and thrombotic risk if treatment is interrupted; discuss with haematology before stopping aspirin.
When to Check a Blood Count Before Dental Treatment
A FBC is not routine for healthy patients. Check or request when the history suggests:
- Symptoms of anaemia (lethargy, dyspnoea, pallor).
- Known haematological disease, chemotherapy or recent transplant.
- Unexplained bruising, petechiae or prolonged bleeding after previous extractions.
- Chronic renal or liver disease.
- Patients on anticoagulants where additional bleeding risk is suspected.
For established haematology patients, the latest counts should be obtained from the haematology team - do not guess.
A 62-year-old patient presents with a smooth, beefy-red painful tongue, recurrent aphthae and fatigue. The most likely underlying deficiency is:
A 24-year-old with sickle cell disease attends for routine restorative care. Which aspect of the appointment is most important to prevent a sickle crisis?
A patient on chemotherapy for acute myeloid leukaemia needs an urgent extraction. The platelet count is 38 x10^9/L. The most appropriate action is:
A 68-year-old presents with multiple punched-out radiolucencies in the mandible, fatigue, thirst and a raised M band on serum electrophoresis. The most likely diagnosis is:
Which oral feature is most characteristic of acute myeloid leukaemia, particularly the monocytic M4/M5 variants?