Coagulation Profile

Hemoglobin

73 g/L

(115–145)

Platelets

46 × 10⁹/L

(150–400)

Prothrombin time

33 s

(10–12)

INR

3.3

(0.7–1.3)

Activated partial thromboplastin time

102 s

(25–37)

Fibrinogen

0.6 g/dL

(1.5–4)

D dimer units

1026 ng/mL

(<250)

Questions

1.

What is the differential diagnosis of a low platelet count?
2.

What is the likely cause of the low platelets in this patient, and how is this condition diagnosed?
3.

Which other clinical states are associated with it?
4.

Can you describe the pathophysiology behind this condition?
5.

What are the principles of management of this condition?
6.

Most patients suffering this complication require extensive transfusion of blood products. What are the short- and long-term complications of transfusions of blood products?
7.

What is the prothrombin time, and how is it related to the INR?

Answers

1 Thrombocytopenia is defined as a platelet count of less than 150 × 10⁹/L⁷. It may be due to:

A decreased production of platelets:
- Selective impairment of platelet production: drugs (alcohol, thiazide diuretics, cytotoxic drugs) and viral infections
- Generalized disease of the bone marrow: aplastic anemia or marrow infiltration in leukemia or dissemination cancer
Decreased platelet survival
- With an immune basis: idiopathic thrombocytopenia purpura, systemic lupus erythematosus, drugs (heparin), and infections (infectious mononucleosis, HIV, CMV)
- Without an immune basis: disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and cardiopulmonary bypass
Sequestration
- Hypersplenism
Dilutional
- Following massive transfusion of stored blood

2 The likely diagnosis in this patient is disseminated intravascular coagulation (DIC). The diagnosis of DIC is not made by the examination of a single laboratory marker but based on the combination of clinical history and a number of test results [1, 2].

Features suggestive of DIC in the clinical history include the presence of clinical conditions known to trigger DIC (see below) and also the clinical presentation due to the resultant consumptive coagulopathy: widespread petechiae and ecchymosis and blood oozing from wound sites, intravenous lines, catheters, and surgical drains. When injury to the pulmonary vasculature occurs, hemoptysis and acute respiratory distress syndrome may result. Other serious complications of DIC include acute renal failure, thrombosis, gangrene, and loss of digits, intracerebral hematoma, and cardiac tamponade.

Laboratory features suggestive of DIC include: