Adult Emergency Medicine: Idiopathic Thrombocytopenic Purpura

Thursday 1 May 2014

Idiopathic Thrombocytopenic Purpura

ITP is more common in children, than in adults - but I've come across it in the adult syllabus first...so we'll cover kids and adults now.

Pathophysiology
Once again, go no-where else but the Calgary Guide!

- IgG mediated
- Platelets get prematurely destructed. Instead of lasting 8 - 10 days, they only last a few hours.
- Often after a recent cold or other infection
- May be associated with HIV and hepatitis
- May be related to immune disorders or pregnancy.

Epidemiology
- Peak age 2 - 10 years old
- Most cases <5 years
- Can occur in adults in the 3rd and 4th decade
- Acute is more likely to be younger children, and resolves in 1-2 months
- Chronic is >3months, more likely to have underlying disease, rarely remits spontaneously.

Diagnosis
- Platelet count of <100,000 /microLitres
- 40,000 – 90,000 are more concerning for undiagnosed marrow failure or leukemia.
- Normal Hgb and WBC with normal differential.
- The absence of signs of other identifiable causes of thrombocytopenia.

Clinical Features
Cutaneous Bleeding
                Petechiae + Purpura
Mucous Membrane
                Epistaxis
                Wet Purpura – Buccal mucosa, Gingiva, palate, tonsillar pillar purpura or petchiae
                Melena / GIB
                Hematuria
                Menorrhagia
Internal bleeding

Historic points favoring another diagnosis:    Bone/Joint Pain
    Family Hx of easy bruising or low platelets

Exam findings concerning for another diagnosis:    Soft tissue or skeletal morphologic abnormalities
    Nonpetechial rash
    Lymphadenopathy
    Hepatosplenomegaly

Management
Based on clinical findings, rather than absolute platelet count.
IV 1g + steroids 1mg/kg
no platelets unless life threatening bleed
May need splenectomy

HUS

Haemolytic uremic syndrome is characterised by thrombocytopenia. It is normally triggered by E-coli 0157, which is found in healthy cattle. May also be caused by shigella, yersinia, campylobacter, salmonella
Most cases occur in child
ren <10years, and 2/3 of cases occur in <5years. Incidence is increased if antibiotics or antimotility agents have been used.

Clinical Features
With or without diarrhoea
Diarrhoea may be bloody (70%) or just watery.
Lethargy 2- 14 days after diarrhoea
Neurological symptoms in 33% (irritability, seizures, altered mental status)
Decreased urine output in a patient that is clinically well-hydrated
Pallor
Oedema - often periorbital, in the morning