Internal Med 5 Flashcards
Ddx of macrocytic anemia
- B12 deficiency
- Folate deficiency
Ddx of of microcytic anemia
- Iron deficiency
- Lead poisoning
- Thalassemia
- Sideroblastic anemia
What is the next thing you should look at if you have a normocytic anemia
Reticulocyte count
Ddx of normocytic anemia with high reticulocyte count
- Hemorrhage
- Hemolysis
Ddx of normocytic anemia with low reticulocyte count (deficiency dye to underproduction)
- Leukemia
- Aplastic anemia
- Infection
- Medication side effect
Causes of B12 deficiency
- Pernicious anemia (autoimmune destruction of gastric mucosa - recall that parietal cells make intrinsic factor, necessary for B12 absorption)
- Pancreatic insufficiency pancreas creates enzymes that cleave B12 from R-binder)
- Damage to terminal ileum (e.g. Crohn’s) - site of B12 absorption
Lab value to differentiate B12 from folate deficiency
Methylmalonic acid - will be normal in Folate deficiency but increased in B12 deficiency
Difference in clinical picture between folate and B12 deficiency
B12 can lead to neuro defects (methylmalonic acid builds up in myelin of spinal cord)
What is the cause of anemia in anemia of chronic disease
♣ Hepcidin sequesters iron into storage sites
How do you differentiate between iron deficiency anemia and anemia of chronic disease
In anemia of chronic disease ferritin will be high (iron is being stored), and TIBC will be low because liver is pumping out less transferrin molecules because it wants to hide the iron
Describe defect in sideroblastic anemia
♣ Defect in heme synthesis
• Defect in protoporphyrin synthesis leads to iron buildup in the mitochondria =iron-laden mitochondria form a ring around nucleus of erythroid precursors
Causes of sideroblastic anemia
- Congenital = ALA synthetase deficiency
- Acquired = lead poisoning, alcohol
Describe hereditary spherocytosis
o Defect of RBC cytoskeleton proteins
o Membranes are formed and lost over time
♣ Loss of membrane = spherocytes
♣ Spherocytes cannot maneuver through splenic sinusoids so are consumed by macrophages
Describe findings in hereditary spherocytosis
♣ Spherocytes with loss of central pallor
♣ Increased RDW – cells of all different sizes
♣ Increased MCHC (mean corpuscular hemoglobin concentration) – cell shrinks but Hb remains the same
♣ Splenomegaly and jaundice – short lifespan of spherocytes and chronic hemolysis causes high hemoglobin turnover
♣ Pigmented gallstones and dark urine due to hyperbilirubiniemia
♣ Aplastic crisis
Diagnosis of hereditary spherocytosis
♣ Osmotic fragility test – High percentage of lysis of RBCs in hypotonic solution
Treatment of hereditary spherocytosis
♣ Splenectomy
What type of anemia will you see in sickle cell
Normocytic anemia with high reticulocyte count
Describe paroxysmal nocturnal hemoglobinuria
o Deficiency of GPI, which usually anchors DAF (CD55) to RBC membrane to protect from complement destruction
♣ Complement is activated in acidic situations
♣ Lysis occurs at night due mild respiratory acidosis
What does S3 heart sound indicate and what are causes
• S3 = rapid flow of blood from the atria to the ventricles
o Presence of S3 in adults indicates volume overload (e.g. congestive heart failure, advanced mitral or tricuspid regurgitation) or dilated ventricles
o Causes of S3 heart sound:
♣ Dilated cardiomyopathy, congestive heart failure, mitral regurgitation, L-to-R shunting