User:Cirqueduchat/sandbox

= Reticulocytopenia = Description/Lead - this is a sign of disease not a disease itself, it is also not the same thing as aplastic crisis or bone marrow failure.

Definition
A decrease in the reticulocyte count below normal threshold (relative reticulocytopenia may occur in individuals with elevated retic counts at baseline). May indicate ineffective erythropoiesis/bone marrow dysfunction. Reticulocytopenia can lead to anemia as the reticulocyte is the precursor to RBC.

Differential Diagnoses

 * Parvovirus B19 infection
 * Aplastic Anemia
 * Pure red cell aplasia e.g. diamond blackfann anemia (hereditary bone marrow failure syndromes)
 * Malignancy
 * Other infection e.g. malaria
 * CKD
 * Cirrhosis
 * Nutritional deficiencies (B12, folate)

Pathophysiology
Depends on the cause

Parvo - virus replicates in reticulocytes and causes apoptosis of retics which then leads to reticulocytopenia, may lead to anemia as well if person has underlying red cell disorder

Nutritional - lower nutrient availability leads to lower erythropoiesis levels

Evaluation

 * CBC
 * Blood smear
 * Retic Index - compare to baseline
 * Bone marrow aspiration
 * Patients with hemoglobinopathies such as SCD may have vaso-occlusive crises at the same time
 * Parvovirus IgG/IgM to evaluate for current infection - in absence of active infection must consider other causes

Management

 * may have to transfuse PRBCs if patient has low enough Hb to allow for oxygen delivery to tissues
 * can do partial exchange transfusion if there is concern for volume overload that may lead to heart failure e.g. chronic anemia patients
 * may have to use colony-stimulating factors
 * Treat underlying deficiency if present e.g. folate replacement

Complication: Aplastic Crisis
Transient decrease in erythropoesis resulting in low reticulocyte count with decrease in Hb >/= 3 g/dL is considered aplastic crisis. For the decrease in all cell lineages (pancytopenia), see aplastic anemia/bone marrow failure. Most cases of aplastic crises are seen in people with hemolytic disorders and superimposed infection with Parvovirus B19 (most of the time) or other pathogen.
 * Parvovirus B19/Other infection (transient aplastic crisis)
 * usually parvovirus
 * present with high viral titers during profound anemia. less likely to have typical parvo rash.
 * immunity lasts for several years and adults are less affected than children
 * may be salmonella, s. pneumo, other strep
 * Predisposed individuals - those who rely on frequent regeneration of RBCs due to shorter RBC lifespan or decreased RBC production
 * hemolytic disorders - hereditary spherocytosis
 * hemoglobinopathies. - sickle cell disease, thalassemia,
 * Red cell enzymopathies - G6PD, PK deficiency,
 * Autoimmune hemolytic anemias
 * Chronic anemias, blood loss- low baseline production
 * may occur in people without underlying hematologic disease
 * rely on frequent regeneration/turnover of RBCs due to destruction/hemolysis - RBC lifespan 12-15 days vs 120 days which is normal lifespan of RBC
 * Typically have reticulocytosis and rely on this higher production of RBCs to carry oxygen to tissues
 * Timeline
 * Typically bone marrow recovery occurs within a week spontaneously, but the patient may require Hb supplementation to reduce chance of serious complications from resulting anemia
 * Complications
 * profound anemia can lead to complications such as congestive heart failure (due to increased plasma volume with anemia), bone marrow necrosis