Thrombocytopenia, or low platelet count, is a hematological condition that can range from asymptomatic to life-threatening. It can occur due to decreased production, increased destruction, or abnormal distribution of platelets in the bloodstream. The condition is often encountered in clinical practice across all specialties—from oncology and internal medicine to surgery and emergency care.
To remember the myriad causes of thrombocytopenia, medical professionals use a reliable memory aid: the “PLATELETS” mnemonic, which stands for:
- P – Platelet disorders
- L – Leukemia
- A – Anaemia
- T – Trauma
- E – Enlarged spleen
- L – Liver disease
- E – Ethanol (alcohol)
- T – Toxins
- S – Sepsis
This article provides an in-depth analysis of each of these causes, with supporting clinical relevance, diagnostic tips, and therapeutic guidance for students, clinicians, and curious readers alike.
What Is Thrombocytopenia?
Thrombocytopenia is defined as a platelet count below 150,000/μL. It can lead to symptoms such as:
- Easy bruising
- Prolonged bleeding from cuts
- Petechiae (tiny red dots on the skin)
- Gum or nose bleeding
- Menorrhagia (heavy periods)
- Life-threatening internal bleeding in severe cases
A normal platelet count ranges from 150,000 to 450,000/μL. Anything below this should trigger an investigation into the underlying cause.
The “PLATELETS” Mnemonic: Unpacking the Causes
Let’s explore the detailed pathophysiology and clinical implications of each component in the mnemonic.
P – Platelet Disorders
This refers to primary thrombocytopenia, often caused by:
a. Immune Thrombocytopenic Purpura (ITP)
- Autoimmune destruction of platelets
- Common in children post-viral illness and in adults with autoimmune conditions
- Bone marrow shows normal megakaryocytes
b. Congenital Platelet Disorders
- Wiskott-Aldrich syndrome
- Bernard-Soulier syndrome
- May-Hegglin anomaly
c. Drug-Induced Thrombocytopenia
- Heparin (Heparin-Induced Thrombocytopenia - HIT)
- Sulfa drugs
- Quinidine
Diagnosis requires clinical history, peripheral smear, and sometimes antibody testing.
L – Leukemia
Leukemia, especially acute leukemias (AML, ALL), can cause severe thrombocytopenia due to:
- Bone marrow infiltration by malignant blasts
- Suppression of normal megakaryopoiesis
- Pancytopenia with blast cells in peripheral smear
Clues:
- Unexplained bruising or bleeding
- Fatigue, infections, pallor
- Hepatosplenomegaly, lymphadenopathy
Bone marrow biopsy is essential for diagnosis.
A – Anaemia
Several types of anaemia, particularly those involving bone marrow failure, can result in reduced platelet production:
a. Aplastic Anaemia:
- Pancytopenia
- Hypocellular marrow
- Can be idiopathic, viral-induced, or drug-related
b. Megaloblastic Anaemia (B12 or Folate Deficiency):
- Impaired DNA synthesis affects all cell lines
- Macrocytic anaemia with giant platelets
c. Myelodysplastic Syndrome (MDS):
- Dysplastic, ineffective hematopoiesis
- Elderly patients with cytopenias
T – Trauma
Significant physical trauma can cause thrombocytopenia by:
- Acute blood loss reducing circulating platelets
- Hemodilution after fluid resuscitation
- Consumption of platelets in massive transfusions
In trauma-induced coagulopathy, platelets and clotting factors are depleted rapidly.
Always monitor platelet levels in ICU and emergency trauma settings.
E – Enlarged Spleen (Splenomegaly)
An enlarged spleen sequesters platelets, leading to a drop in circulating count. This is known as hypersplenism.
Causes of Splenomegaly:
- Portal hypertension (e.g., cirrhosis)
- Hematologic malignancies (e.g., lymphomas)
- Infections (malaria, tuberculosis)
- Infiltrative diseases (sarcoidosis)
Patients may also have anaemia and leukopenia.
Ultrasound or CT scan can confirm spleen size.
L – Liver Disease
The liver plays a major role in platelet production and regulation.
In Liver Disease:
- Decreased thrombopoietin production (a hormone that stimulates platelet synthesis)
- Portal hypertension leads to splenomegaly
- Increased consumption due to coagulopathy
Chronic liver conditions like cirrhosis, hepatitis B/C, and alcoholic liver disease are commonly associated with thrombocytopenia.
E – Ethanol (Alcohol)
Chronic alcohol consumption can impair:
- Bone marrow function, suppressing megakaryocytes
- Liver function, reducing thrombopoietin
- Folic acid absorption, leading to megaloblastic anaemia
Even binge drinking can temporarily lower platelet counts.
Reversible with alcohol cessation and nutritional support.
T – Toxins
Various toxins and medications can damage bone marrow or trigger immune responses:
Drug-Induced:
- Chemotherapy agents
- Valproic acid
- Linezolid
Environmental:
- Benzene exposure
- Radiation
Management includes identifying and withdrawing the toxin, and sometimes immunosuppression.
S – Sepsis
Sepsis-induced thrombocytopenia is a poor prognostic marker.
Mechanisms:
- Disseminated Intravascular Coagulation (DIC)
- Increased platelet consumption
- Cytokine-mediated suppression
Marked by:
- Elevated PT, aPTT, D-dimer
- Schistocytes on peripheral smear
- Multi-organ failure
Immediate ICU care, antibiotics, and supportive therapy are critical.
Types of Thrombocytopenia
| Type | Cause |
|---|---|
| Decreased production | Leukemia, anaemia, toxins |
| Increased destruction | ITP, sepsis, DIC |
| Sequestration | Splenomegaly |
| Dilutional | Massive transfusion |
Diagnostic Approach to Thrombocytopenia
History and Physical Examination
- Recent infections, medications
- Alcohol use, bleeding symptoms
- Spleen palpation
Laboratory Tests
- CBC with peripheral smear
- Coagulation profile (PT, aPTT, INR)
- Bone marrow biopsy (if needed)
- Reticulocyte count
- Vitamin B12, Folate, LFTs
Treatment Options
| Cause | Treatment |
|---|---|
| ITP | Corticosteroids, IVIG, Rituximab |
| Leukemia | Chemotherapy, bone marrow transplant |
| Aplastic anaemia | Immunosuppressants, transplant |
| Alcohol-induced | Abstinence, nutritional support |
| Sepsis | ICU care, antibiotics, platelet transfusion |
| Liver disease | Manage cirrhosis, transplant if advanced |
Platelet transfusion is reserved for active bleeding or very low counts (<10,000/μL).
Clinical Clues for Urgency
Seek emergency care if a patient with thrombocytopenia presents with:
- Black tarry stools (melena)
- Hematuria
- Neurological signs (suggesting intracranial bleed)
- Sudden drop in platelet count
Frequently Asked Questions (FAQs)
What platelet count is considered dangerously low?
<20,000/μL can be life-threatening, particularly if bleeding is present.
Can thrombocytopenia be cured?
It depends on the cause. Some (like ITP or drug-induced) are reversible; others (like leukemia) require long-term therapy.
Does thrombocytopenia cause fatigue?
Yes, especially if associated with anaemia or systemic illness.
Is low platelet count always cancer?
No. Many causes are benign or reversible—like infection, drugs, or alcohol.
Can diet help increase platelets?
Foods rich in folate, B12, and vitamin C may help. But medical evaluation is essential.
Summary Table: “PLATELETS” Mnemonic for Thrombocytopenia Causes
| Letter | Cause | Mechanism |
|---|---|---|
| P | Platelet disorders | Immune destruction, congenital defects |
| L | Leukemia | Bone marrow infiltration |
| A | Anaemia | Impaired production (e.g., aplastic, megaloblastic) |
| T | Trauma | Hemodilution, blood loss |
| E | Enlarged spleen | Sequestration of platelets |
| L | Liver disease | Decreased thrombopoietin, hypersplenism |
| E | Ethanol | Marrow suppression, folate deficiency |
| T | Toxins | Drug-induced, environmental |
| S | Sepsis | Consumption, DIC, marrow suppression |
Final Thoughts
Thrombocytopenia is not a diagnosis—it's a clue. From subtle bruising to massive internal hemorrhage, the spectrum of presentation is broad and the causes are diverse. The “PLATELETS” mnemonic offers a quick, structured way to remember the common and critical etiologies. Whether you're managing an ICU patient or reviewing a CBC in a routine check-up, knowing this framework can guide faster and more accurate clinical decisions.
