A 49-year-old female presents with confusion. The results of her blood tests are as follows:

Parameter

Patient Value

Normal Adult Range

Haemoglobin

86 q/L*

135 - 180

White Cell Count

11.2 x 109/L*

4.0 - 11.0

Platelets

23 x 109/L*

150 - 400

Prothrombin time

14.0 sec

12.0 - 16.5

Activated partial thromboplastin time

35.0 sec

27.0 - 38.5

Fibrinogen

2.1 q/L

2.0 - 4.0

Thrombin time

14.0 sec*

11.5 - 13.5

Urea

12.1 mmol/L*

3.0 - 8.0

Creatinine

356 µmol/L*

45 - 90

Lactate  dehydrogenase

2342 U/L*

140 - 280

a) Give the likely diagnosis. (20% marks)

b) Give an additional test to support your diagnosis. (10% marks)

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College answer

a)    Thrombotic thrombocytopaenic purpura                      
Haemolytic-uraemic syndrome 
Systemic lupus erythromatosis 
MAHA (1 mark only) 
 
b)    ADAMTS13 (TTP)                                     
Positive Shiga toxin / Entero-haemorrhagic E coli test (HUS)  
ANA / anti-dsDNA (SLE)  
Blood film 
Reticulocyte count 
Haptoglobins 
 

Discussion

a)

The diagnosis of TTP/HUS suggests itself, even though the "pentad" of symptoms is incomplete:

  • Thrombocytopenia is present
  • Microangiopathic hemolytic anemia is suggested by the LDH ad low haemoglobin
  • Neurologic abnormalities are present
  • Renal failure is present
  • Fever is absent

The low-ish fibrinogen suggests that a TTP-related excess of vWF has produced a systemic prothrombotic state, with microvascular thrombosis consuming all the fibrinogen.

b)

ADAMTS-13 level is of course the most important supportive test. The relevanc of this protein is discussed in the chapter on TTP/HUS.

References

References

George, James N. "Thrombotic thrombocytopenic purpura." New England Journal of Medicine 354.18 (2006): 1927-1935.