Hemolytic anemia laboratory findings: Difference between revisions

Jump to navigation Jump to search
Line 25: Line 25:
* The problem arises because the reticulocyte count is not really a ''count'' but rather a ''percentage'': it reports the number of reticulocytes as a percentage of the number of red blood cells.  
* The problem arises because the reticulocyte count is not really a ''count'' but rather a ''percentage'': it reports the number of reticulocytes as a percentage of the number of red blood cells.  
* In anemia, the patient's red blood cells are depleted, creating an erroneously elevated reticulocyte count.  
* In anemia, the patient's red blood cells are depleted, creating an erroneously elevated reticulocyte count.  
The idea of the RPI is to assess whether the [[bone marrow]] is producing an appropriate response to an anemic state. Reticulocyte production should increase in response to any loss of red blood cells. It should increase within 2-3 days of a major acute [[hemorrhage]], for instance, and reach its peak in 6-10 days.{{ref|Hoffbrand}} If reticulocyte production is not raised in response to anemia, then the anemia may be due to an acute cause with insufficient time to compensate, or there is a defect with red blood cell production in the bone marrow. Marrow defects include nutritional deficiencies (i.e. iron, folate, or B12) or insufficient [[erythropoietin]], the stimulus for  red blood cell production.
* The idea of the RPI is to assess whether the [[bone marrow]] is producing an appropriate response to an anemic state.  
* Reticulocyte production should increase in response to any loss of red blood cells.
* It should increase within 2-3 days of a major acute [[hemorrhage]], for instance, and reach its peak in 6-10 days.  
* If reticulocyte production is not raised in response to anemia, then the anemia may be due to an acute cause with insufficient time to compensate, or there is a defect with red blood cell production in the bone marrow.  
* Marrow defects include nutritional deficiencies (i.e. iron, folate, or B12) or insufficient [[erythropoietin]], the stimulus for  red blood cell production.


Reticulocyte Production Index is calculated as follows:
Reticulocyte Production Index is calculated as follows:

Revision as of 15:26, 25 September 2012

Hemolytic anemia Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Hemolytic anemia from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms

Physical Examination

Laboratory Findings

X Ray

CT Scan

MRI Scan

Echocardiography or Ultrasound

Imaging Findings

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Hemolytic anemia laboratory findings On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Hemolytic anemia laboratory findings

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Hemolytic anemia laboratory findings

CDC on Hemolytic anemia laboratory findings

Hemolytic anemia laboratory findings in the news

Blogs on Hemolytic anemia laboratory findings

Directions to Hospitals Treating Hemolytic anemia

Risk calculators and risk factors for Hemolytic anemia laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Hemolytic anemia is anemia caused secondary to shortened survival of circulating red blood cells. The normal life span of RBCs is 110 to 120 days. RBC destruction before that time is defined as hemolytic anemia. As opposed to the normal senecence of RBC, the random hemolysis (premature RBC death) is increased in hemolytic anemia.

Laboratory Findings

Peripheral blood smear

  • Fragments of the red blood cells ("schistocytes") can be present.
  • Some red blood cells may appear smaller and rounder than usual (spherocytes).
  • Reticulocytes are present in elevated numbers. This may be overlooked if a special stain is not used
  • The reticulocytes response act as an important indicator for the severity of the hemolytic anemia. The different methods used to judge the correct response are, absolute reticulocyte count, corrected reticulocyte count, and reticulocyte production index.

Reticulocyte count

Absolute reticulocyte count

The normal values are:

  • RBC count - 5 million/microLitre
  • Reticulocyte count - 0.5 -1.5 %
  • Absolute reticulocyte count - 25,000 to 75,000/microLitre

Corrected reticulocyte count

The corrected absolute reticulocyte count = absolute reticulocyte count / reticulocyte maturation time (in days).

Reticulocyte production index

  • Reticulocytes are newly-produced red blood cells. They are slightly larger than totally mature red blood cells, and have some residual ribosomal RNA. The presence of RNA allows a visible blue stain to bind or, in the case of fluorescent dye, result in a different brightness. This allows them to be detected and counted as a distinct population.
  • The Reticulocyte production index (RPI, also called a corrected reticulocyte count) is a calculated value used in the diagnosis of anemia.
  • This calculation is necessary because the raw reticulocyte count is misleading in anemic patients.
  • The problem arises because the reticulocyte count is not really a count but rather a percentage: it reports the number of reticulocytes as a percentage of the number of red blood cells.
  • In anemia, the patient's red blood cells are depleted, creating an erroneously elevated reticulocyte count.
  • The idea of the RPI is to assess whether the bone marrow is producing an appropriate response to an anemic state.
  • Reticulocyte production should increase in response to any loss of red blood cells.
  • It should increase within 2-3 days of a major acute hemorrhage, for instance, and reach its peak in 6-10 days.
  • If reticulocyte production is not raised in response to anemia, then the anemia may be due to an acute cause with insufficient time to compensate, or there is a defect with red blood cell production in the bone marrow.
  • Marrow defects include nutritional deficiencies (i.e. iron, folate, or B12) or insufficient erythropoietin, the stimulus for red blood cell production.

Reticulocyte Production Index is calculated as follows:

1.<math>Retic Index = Retic Count * {Hematocrit \over Normal Hematocrit}</math>

A value of 45 is usually used as a normal hematocrit.

2.The next step is to correct for the longer life span of prematurely released reticulocytes in the blood--a phenomenon of increased red blood cell production. This relies on a table:

Hematocrit (%)......Retic

So, in a person whose reticulocyte count is 5%, hemoglobin 7.5 g/dL, hematocrit 25%, the RPI would be:

5 x [corrected retic count]/[maturation correction] = 5 x (25/45) /2 = 1.4

  • The reticulocyte index (RI) should be between 1.0 and 2.0 for a healthy individual.
  • RI < 2 with anemia indicates decreased production of reticulocytes and therefore red blood cells.[2]
  • RI > 2 with anemia indicates loss of red blood cells (destruction, bleeding, etc) leading to increased compensatory production of reticulocytes to replace the lost red blood cells.{{

It corrects the reticulocyte response through two mechanism:

  • The degree of anemia (done by normalizing hematocrit of 45%)
  • Reticulocyte maturation time (RMT)
  • The Reticulocyte maturation time is 1.0 days for a hematocrit of 45 % to 2.5 days for a hematocrit of 15 %:
  • Reticulocyte production index = Reticulocytes % x (HCT / 45) x (1 / RMT)
    • Normal value of RPI is 1.
    • RPI is said to be increased if it is more than 2
    • Value low than 1 shows hypoproliferative responses

Other lab tests

Liver function test

  • The level of unconjugated bilirubin in the blood is elevated. This may lead to jaundice.

Urinalysis

  • Hemosiderin in the urine indicates chronic intravascular hemolysis.
  • There is also urobilinogen in the urine.

(Images shown below are courtesy of Melih Aktan MD, Istanbul Medical Faculty - Turkey, and Hospital Universitario La Fe Servicio Hematologia)

References