Hematology Week 4 Summary

Question 16

A 33 year old patient presents with fatigue to her family physician’s office. Her blood work is shown below. What is the differential for her blood findings and why?

What is your differential diagnosis for a microcytic anemia?

“TAILS”

• Thallasemia
• Anemia of chronic disease
• Iron deficiency anemia
• Lead poisoning
• Sideroblastic anemia

What ferritin value increases the likelihood of iron deficiency?
A ferritin of less than 18 ug/L has a likelihood ration of over 41 for iron deficiency anemia.

What is the gold standard for investigation?
A bone marrow biopsy.

Guyatt et al. Diagnosis of iron-deficiency anemia in the elderly. (1990) AJM 88:205-209

Question 17

Compare and contrast investigations differentiating iron deficiency anemia, anemia of chronic inflammation, and thallasemia.

Question 18

An 18 year old female re-presents to the emergency department after 3 days of severe migraines. Her CBC is shown below. What other investigations are pertinent in her diagnosis?

Points of discussion: It is imperative that any diagnosis of microangiopathic hemolytic anemia be diagnosed immediately due to the inherent mortality risk with disorders such as TTP or DIC. Investigations include:

• Peripheral blood film to assess for fragmentation
• CBC, LDH, bilirubin, haptoglobin, reticulocyte count
• Group and screen, direct antiglobulin test
• Lytes, Cr, calcium panel (Ca, Mg, phosphate, albumin), liver enzymes
• Urinalysis
• PT, PTT, fibrinogen
• Add septic workup including stool sample in presence of diarrhea.
• Consider adding HIV, HCV, and autoimmune screen if suspicion of TTP
• ADAMTS13 screening if suspicion of TTP
• Beta HCG for all women of childbearing age

What is the management of TTP?

Points of discussion: This is a clinical diagnosis with a mortality of >90% without treatment. Do not wait for ADAMT13 testing to support a diagnosis.

1. Immediate transfer to a plasmapheresis center
2. Frozen plasma to be administered immediately to replete deficient ADAMTS13
3. Daily plasmapheresis (Repletes ADAMTS13 and removes Antibody targeting ADAMTS13)
4. Folic acid, iron (if deficient), role of prednisone and ASA is controversial

Scully et al. Guidelines on the diagnosis and management of thrombotic thrombocytopenic purpura and other thrombotic microangiopathies. British TTP Guidelines; 2012

Question 19

Consider the blood tests used when evaluating a patient with autoimmune hemolysis. How does a DAT work? What is your differential diagnosis for a DAT + hemolytic anemia?

Direct Antiglobulin Test: Detects the presence of an antibody (IgG) or complement (C3d) bound in vivo to red blood cells in a patient’s circulation.

Coombs reagent is a monospecific immunoglobulin against IgG or C3 bound to the RBC surface. Agglutination indicates a positive test.

• Auto Antibody
  • Warm autoimmune hemolytic anemia (positive test to IgG)
  • Cold autoimmune hemolytic anemia (positive to C3d)
  • Paroxysmal Cold Hemoglobinuria
  • Mixed
  • Drug effect
• Allo Antibody
  • Transfused blood, IVIG
  • Stem Cell transplant
  • Hemolytic disease of the newborn
• Hyperproteinemia
  • IVIG
  • MM/Plasma Cell dyscrasia
  • Hyperalbumineria

Question 20

A 36 year old female is post-op day 3 for a colectomy for ulcerative colitis. She is on oral iron replacement and feels well with a minimal need for analgesia. Her chart indicates that her heart rate was 110 bpm and there is an order for 2 units of packed red blood cells if the Hgb is <100g/L. You question the evidence behind such an order and call the surgical service covering her care.

Points of Discussion: What are the indications for transfusion? Is there any evidence that exists to help with when and how much blood should be transfused?

Indications for Transfusion

• Symptomatic anemia in a NORMOVOLEMIC patient
• Hb <70g/L
• Hb <80g/L in chronic transfusion patients
• Inappropriate if Hb >100g/L
• Atherosclerosis, unstable angina, other cardiac, pulmonary,↑ oxygen consumption, unpredictable bleeding
• DO NOT transfuse based solely on Hb
  • Always use Hb in combination with clinical status and history

Discussion Point: The TRICC Trial was a RCT of transfusion requirements in critical care to determine whether a restrictive strategy of red-cell transfusion (i.e. transfuse once Hgb < 70g/L to maintain a Hgb between 70–90g/L) and a liberal strategy (transfuse to keep Hgb >100g/L) produced equivalent results in critically ill patients. Results compared the rates of death from all causes at 30 days and the severity of organ dysfunction.

*Illustrates statistically significant results

Carson JL et al. Red blood cell transfusion: a clinical practice guideline from the AABB*. Ann Intern Med. 2012 Jul 3;157(1):49-58

Hebert et al. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. Transfusion Requirements in Critical Care Investigators, Canadian Critical Care Trials Group. NEJM 1999;340:409-17