After reading this note you will be able to recognise, investigate and initiate appropriate management of thrombocytopenia and platelet function disorders in Kenyan clinical rotations. Always verify drug choices, doses and local protocols against the Kenya MoH guideline and your hospital formulary.
Definition
- Thrombocytopenia: platelet count < 150 × 10⁹/L on peripheral blood film.
- Severe thrombocytopenia: < 20 × 10⁹/L (high risk of spontaneous bleeding).
- Platelet function disorder: normal platelet count with impaired adhesion, activation or aggregation leading to abnormal bleeding time or specialised testing.
Anatomy and physiology you need
| Structure | Role in haemostasis |
|---|---|
| Megakaryocyte (bone marrow) | Produces platelets; regulated by thrombopoietin |
| Platelet membrane receptors (GPIb, GPIIb/IIIa) | Adhesion to collagen, aggregation |
| Granules (α, dense) | Release ADP, serotonin, fibrinogen‑binding proteins |
| Endothelium (von Willebrand factor) | Mediates platelet adhesion under shear |
| Coagulation cascade (intrinsic & extrinsic) | Provides fibrin scaffold for platelet plug |
Causes and risk factors
| Category | Common Kenyan aetiologies |
|---|---|
| Decreased production | HIV, TB (marrow infiltration), malaria, sickle cell disease, aplastic anaemia, chemotherapy, severe malnutrition |
| Increased destruction | Immune thrombocytopenia (ITP), drug‑induced (e.g., quinine, penicillins), disseminated intravascular coagulation (sepsis, severe malaria), hypersplenism (schistosomiasis, portal hypertension) |
| Sequestration | Splenomegaly from malaria, schistosomiasis, sickle cell, portal hypertension |
| Platelet function defects | Glanzmann thrombasthenia (rare), Bernard‑Soulier, antiplatelet drugs (aspirin, clopidogrel), uremia |
| Mixed/other | Pregnancy‑associated ITP, viral hepatitis, rheumatic fever (immune complexes) |
Pathophysiology
- Infection (HIV, malaria, TB) → marrow suppression or immune‑mediated platelet clearance → ↓ platelet count.
- Immune thrombocytopenia → auto‑antibodies bind platelet GPIIb/IIIa → Fc‑mediated splenic phagocytosis → thrombocytopenia.
- DIC → widespread coagulation → consumption of platelets & clotting factors → low count + bleeding.
- Splenomegaly → enlarged spleen sequesters 30‑50 % of circulating platelets → functional thrombocytopenia.
- Drug‑induced → hapten formation or direct toxicity → platelet destruction or impaired production.
Clinical features
| History question | Why it matters |
|---|---|
| Onset of bruising or petechiae (sudden vs gradual) | Sudden fall suggests acute consumptive process (e.g., DIC, severe infection) whereas gradual decline fits chronic marrow suppression or immune thrombocytopenia. |
| Recent infections (malaria, HIV, TB, viral gastro‑enteritis) | Many tropical infections cause platelet sequestration or immune destruction; HIV and TB are common causes of secondary immune thrombocytopenia in Kenya. |
| Drug exposure (antibiotics, antimalarials, antiretrovirals, traditional medicines) | Drug‑dependent antibodies or marrow toxicity can lower platelet count; identifying the culprit allows withdrawal. |
| Bleeding history (mucosal bleeding, epistaxis, menorrhagia, GI bleed, hematuria) | Determines clinical severity and guides urgency of treatment; mucocutaneous bleeding is typical of platelet defects, while deep bleeding may indicate co‑existing coagulopathy. |
| Pregnancy status or recent childbirth | Gestational thrombocytopenia and HELLP syndrome are important differentials; management differs from immune causes. |
| Past haematological disease (sickle cell, thalassaemia, aplastic anaemia) | Underlying marrow pathology predisposes to low platelets and may affect choice of definitive therapy. |
| Family history of bleeding diathesis | Inherited platelet function disorders (e.g., Bernard‑Soulier, Glanzmann) present with lifelong bleeding; distinguishes from acquired causes. |
| Alcohol intake, nutritional status | Chronic alcohol or malnutrition can suppress marrow production; addressing these factors is part of management. |
| Splenomegaly or abdominal pain | Suggests sequestration (e.g., portal hypertension, malaria, sickle cell) or infiltrative disease. |
| Recent surgery or trauma | Provides context for possible consumptive loss or need for peri‑operative platelet support. |
Examination findings and their rationale
| Finding | Pathophysiological explanation |
|---|---|
| Petechiae (0.5 mm–2 mm) on trunk/extremities | Capillary rupture due to insufficient platelet plug formation; classic for platelet numbers <20 × 10⁹/L. |
| Purpura or ecchymoses >5 mm | Larger vessel leakage when platelet plug is inadequate; severity correlates with count. |
| Mucosal bleeding (gum, oral, nasal) | Platelets are first line for mucosal haemostasis; low counts produce easy bleeding. |
| Hematuria or melena | Indicates that platelet deficiency is severe enough to allow bleeding from urinary or gastrointestinal mucosa. |
| Splenomegaly | Platelet sequestration in an enlarged spleen (common in malaria, sickle cell, portal hypertension). |
| Hepatomegaly or signs of chronic liver disease | Reduced thrombopoietin production and portal hypertension‑related sequestration. |
| Lymphadenopathy | May point to lymphoproliferative disorders (e.g., lymphoma) causing marrow infiltration or immune-mediated destruction. |
| Signs of systemic infection (fever, rigors) | Suggests consumptive processes (sepsis‑related DIC) or infection‑driven immune thrombocytopenia. |
| Joint swelling or rash (malar, malar‑like) | May indicate systemic autoimmune disease (SLE) that can cause immune platelet destruction. |
| Neurological deficits or severe headache | Rare but possible with intracranial hemorrhage when platelets are critically low. |
Differential diagnosis
| Condition | Points toward it | Key discriminators |
|---|---|---|
| Immune thrombocytopenic purpura (ITP) | Isolated low platelets, recent viral infection, no splenomegaly | Normal marrow, rapid response to IVIG or steroids, absence of systemic illness |
| Drug‑induced thrombocytopenia | New drug exposure, temporal relation, abrupt fall | Resolution after drug withdrawal, often severe but short‑lived |
| Malaria‑associated thrombocytopenia | Recent travel/ residence in endemic area, fever, splenomegaly | Positive malaria smear, rapid platelet rise after antimalarial therapy |
| HIV‑related thrombocytopenia | Positive HIV test, opportunistic infections, chronic course | Low CD4 count, response to antiretroviral therapy, possible concurrent anemia |
| Disseminated intravascular coagulation (DIC) | Sepsis, obstetric complications, abnormal PT/aPTT, elevated D‑dimer | Prolonged coagulation times, low fibrinogen, schistocytes on smear |
| Bone‑marrow infiltration (leukemia, lymphoma) | B symptoms, cytopenias in other lineages, lymphadenopathy | Abnormal blasts on peripheral smear, marrow biopsy showing malignant cells |
| Hypersplenism (portal hypertension, sickle cell) | Enlarged spleen, pancytopenia, history of liver disease or sickle cell | Platelet count improves after splenectomy or portal decompression |
| Inherited platelet function disorders | Lifelong bleeding history, family history, normal platelet count | Abnormal platelet aggregation studies, normal count but defective function |
| HELLP syndrome / gestational thrombocytopenia | Pregnancy >20 weeks, hypertension, elevated liver enzymes | Resolves postpartum, associated with pre‑eclampsia features |
Investigations
| Test | What it answers | Interpretation |
|---|---|---|
| Full blood count with peripheral smear | Presence of isolated thrombocytopenia vs pancytopenia; platelet morphology | Isolated low platelets → peripheral destruction or sequestration; abnormal cells → marrow infiltration |
| Reticulated platelet count (immature platelet fraction) | Bone‑marrow production rate | High fraction → peripheral destruction; low → production problem |
| Coagulation profile (PT, aPTT, fibrinogen, D‑dimer) | Consumptive coagulopathy vs isolated platelet issue | Prolonged PT/aPTT, low fibrinogen, high D‑dimer → DIC |
| HIV serology / viral load | HIV‑related immune thrombocytopenia | Positive → consider antiretroviral optimisation |
| Malaria rapid test / thick smear | Malaria infection | Positive → treat malaria, expect platelet recovery |
| Hepatitis B/C serology | Chronic liver disease causing sequestration | Positive with liver dysfunction labs |
| Autoimmune screen (ANA, anti‑dsDNA) | SLE‑associated thrombocytopenia | Positive ANA with clinical features |
| Bone‑marrow aspirate/biopsy (if indicated) | Production vs infiltration | Normocellular with increased megakaryocytes → peripheral destruction; hypocellular or blasts → marrow failure |
| Imaging (ultrasound abdomen) | Splenomegaly, portal hypertension | Enlarged spleen supports sequestration hypothesis |
| Drug‑dependent platelet antibody testing (rare) | Immune drug reaction | Positive supports drug‑induced ITP |
Diagnosis and severity
- Confirm thrombocytopenia – platelet count <150 × 10⁹/L on two separate samples (unless urgent bleeding).
- Classify by mechanism –
- Peripheral destruction/sequestration – normal/raised immature platelet fraction, often isolated thrombocytopenia, possible splenomegaly.
- Decreased production – low immature platelet fraction, associated cytopenias, abnormal marrow.
- Assign severity (guides transfusion and specialist referral):
| Severity | Platelet count | Clinical implication |
|---|---|---|
| Mild | 100–150 × 10⁹/L | Usually asymptomatic; monitor. |
| Moderate | 50–99 × 10⁹/L | May have mucosal bleeding; consider prophylactic measures. |
| Severe | 20–49 × 10⁹/L | High risk of spontaneous bleed; urgent evaluation, possible platelet transfusion. |
| Life‑threatening | <20 × 10⁹/L | Immediate platelet support, treat underlying cause aggressively. |
- Integrate history, exam, and investigations to label the specific entity (e.g., immune thrombocytopenia, malaria‑associated, DIC, etc.). This final diagnosis directs definitive therapy and informs prognosis.
Management
Immediate stabilisation
- Airway‑breathing‑circulation: Give oxygen, establish large‑bore IV, monitor vitals.
- Control active bleeding: Apply firm pressure, use local haemostatic agents, consider tranexamic acid (antifibrinolytic) if mucosal bleeding is significant.
- Platelet transfusion: Indicated for life‑threatening haemorrhage, intracranial bleed, or platelet count < 10 × 10⁹/L in a stable patient. Use HLA‑matched platelets for refractory immune cases.
- Reverse drugs: Stop or hold antiplatelet agents (aspirin, clopidogrel) and anticoagulants; give vitamin K or prothrombin complex concentrate if warfarin‑related.
Definitive treatment
| Situation | First‑line therapy | Rationale |
|---|---|---|
| Immune thrombocytopenia (ITP) | Corticosteroids (prednisone‑like) | Suppress auto‑antibody production |
| Steroid‑refractory ITP | Intravenous immunoglobulin (IVIG) or anti‑D immunoglobulin | Rapid rise in platelets via Fc‑receptor blockade |
| Severe ITP with bleeding | Combination of steroids + IVIG ± platelet transfusion | Synergistic effect, temporary platelet support |
| Drug‑induced thrombocytopenia | Discontinue offending drug | Removes antigenic stimulus |
| HIV‑associated thrombocytopenia | Optimise antiretroviral therapy; consider steroids if severe | Viral suppression improves marrow output |
| Sepsis/TB‑related consumptive coagulopathy | Treat underlying infection; consider platelet transfusion if count < 20 × 10⁹/L | Removes trigger of platelet consumption |
| Malaria‑related thrombocytopenia | Prompt antimalarial therapy | Parasite clearance restores marrow function |
| Sickle cell vaso‑occlusive crisis with thrombocytopenia | Exchange transfusion if indicated; supportive care | Reduces sickled cells, improves marrow perfusion |
| Bone‑marrow failure (aplastic, leukemia) | Refer to haematology for disease‑specific therapy (e.g., chemotherapy, stem‑cell transplant) | Underlying pathology must be addressed |
Monitoring & follow‑up
- Daily full blood count until platelet trend stabilises.
- Observe for transfusion reactions (fever, chills, urticaria).
- Re‑assess for bleeding signs every 4–6 h in the acute phase.
- After discharge, schedule outpatient review at 1 week, then monthly until platelets > 50 × 10⁹/L.
- Counsel on avoidance of NSAIDs, herbal remedies, and high‑impact activities while thrombocytopenic.
Contra‑indications & safety
- Avoid intramuscular injections when platelets < 20 × 10⁹/L.
- Do not give platelet transfusion for isolated mild ITP without bleeding (ineffective and may sensitize).
- Use caution with antifibrinolytics in patients with disseminated intravascular coagulation.
- Ensure HIV‑positive patients receive prophylaxis for opportunistic infections when on high‑dose steroids.
Complications and prognosis
- Bleeding: epistaxis, gum bleed, gastrointestinal haemorrhage, intracranial haemorrhage (high mortality).
- Refractory thrombocytopenia: may signal underlying marrow failure or chronic immune disease; poorer long‑term outlook.
- Transfusion‑related complications: alloimmunisation, febrile non‑hemolytic reactions, volume overload.
- Infection: immunosuppressive therapy (steroids, IVIG) increases risk; monitor temperature and cultures.
- Pregnancy: severe thrombocytopenia can cause placental abruption or postpartum haemorrhage; multidisciplinary care improves outcomes.
Prognosis varies: drug‑induced and infection‑related thrombocytopenia often resolve with treatment of the trigger; ITP has a chronic relapsing course in 30‑40 % of adults; marrow failure carries a guarded prognosis without definitive therapy.
High‑yield exam points
- Look‑alike conditions: Differentiate ITP (peripheral destruction) from aplastic anemia (production failure) – marrow will be hypocellular in the latter.
- Common wrong first step: Giving platelet transfusion for uncomplicated ITP; the correct first step is immunosuppression.
- Bedside examiner questions:
- “What does a peripheral smear show in immune‑mediated thrombocytopenia?” (large platelets, no schistocytes).
- “Why is a platelet count < 10 × 10⁹/L an emergency even without overt bleeding?” (risk of spontaneous intracranial bleed).
- “How would you distinguish drug‑induced thrombocytopenia from ITP?” (temporal relationship, drug cessation leads to rapid recovery).
Clinical case
Case: A 28‑year‑old woman presents with spontaneous bruising and gum bleeding for 3 days. She is HIV‑positive, on first‑line ART for 2 years, and reports recent flu‑like illness. Examination: pale, petechiae on limbs, oral mucosal bleeding, no organomegaly. Platelet count 8 × 10⁹/L, Hb 11 g/dL, WBC 6 × 10⁹/L. Peripheral smear shows large platelets, no schistocytes.
Questions
- What is the most likely diagnosis?
Answer: Immune thrombocytopenia secondary to HIV.
- What is the immediate management priority?
Answer: Stabilise, give platelet transfusion if bleeding is severe, start high‑dose corticosteroids and IVIG.
- Which long‑term strategy will improve platelet counts?
Answer: Optimise antiretroviral therapy and consider a tapering course of steroids; monitor for relapse.
Practice questions
Question 1
A 45‑year‑old man with newly diagnosed pulmonary TB develops diffuse petechiae and a platelet count of 12 × 10⁹/L. He is not bleeding. What is the next best step?
A. Immediate platelet transfusion
B. Start high‑dose steroids
C. Continue TB treatment, observe, and repeat CBC in 48 h
D. Discontinue rifampicin
Answer: C. Continue TB treatment, observe, and repeat CBC in 48 h
Explanation: Mild thrombocytopenia without bleeding in TB often improves with infection control; transfusion or steroids are unnecessary at this level.
Question 2
A child with severe malaria presents with a platelet count of 30 × 10⁹/L and active epistaxis. Which intervention is most appropriate?
A. Intravenous quinine only
B. Platelet transfusion before antimalarial therapy
C. Start tranexamic acid and give antimalarial drugs
D. Give high‑dose steroids
Answer: C. Start tranexamic acid and give antimalarial drugs
Explanation: Controlling bleeding with an antifibrinolytic and treating the underlying malaria addresses the cause; platelet transfusion is reserved for counts < 10 × 10⁹/L or severe bleed.
Question 3
A 60‑year‑old woman on aspirin for secondary prevention after MI presents with a platelet count of 55 × 10⁹/L and a new intracerebral haemorrhage on CT. What should be done?
A. Continue aspirin, give platelets
B. Stop aspirin, give platelet transfusion
C. Switch aspirin to clopidogrel
D. Give IVIG
Answer: B. Stop aspirin, give platelet transfusion
Explanation: Antiplatelet agents worsen intracranial bleed; platelet transfusion raises count rapidly to aid haemostasis.
Question 4
Which laboratory finding helps differentiate thrombotic thrombocytopenic purpura (TTP) from ITP?
A. Elevated D‑dimer
B. Presence of schistocytes on smear
C. Low reticulocyte count
D. Positive direct Coombs test
Answer: B. Presence of schistocytes on smear
Explanation: Microangiopathic haemolysis in TTP produces fragmented red cells; ITP shows large platelets without schistocytes.
Question 5
A patient with chronic ITP has a platelet count of 25 × 10⁹/L but no bleeding. He is scheduled for elective cataract surgery. What is the safest pre‑operative plan?
A. Proceed without intervention
B. Give a single dose of IVIG the day before surgery
C. Start a short course of steroids 2 weeks prior
D. Transfuse platelets immediately before surgery
Answer: B. Give a single dose of IVIG the day before surgery
Explanation: IVIG raises platelet count rapidly, providing a safe peri‑operative window without the long‑term side effects of steroids; platelet transfusion is less effective in ITP.
Drafted with AI assistance from standard references and reviewed for structure. Check details against your lecture notes and the Kenya MoH guideline.