RBC;

Why does my patient with alcoholic cirrhosis have macrocytic anemia?

FA Manian MD, MPH, , , , , , , , , , , 1 Comment

Macrocytic anemia is commonly due to folate or vitamin B12 (cobalamin) deficiency.1 Deficiency in these vitamins can be related broadly to poor intake, poor absorption, or drug interference. In patients with chronic excess alcohol consumption, both intake and/or absorption of these vitamins may be affected.

Although folate deficiency is increasingly rare in many developed countries due to mandatory folate fortification of flour and uncooked-grain, alcohol use can be associated with malnourishment severe enough to causes folate deficiency. In addition, alcohol itself can alter folate metabolism and absorption.  More specifically, chronic alcohol consumption has been shown to be associated with decreased folate absorption by the small intestine, altered intrahepatic processing and distribution between the systemic and enterohepatic folate circulations as well as increased folate urinary excretion. 2 Though uncommon,3 alcohol can also be associated with a food B12 malabsorption process, whereby despite adequate intake, B12 is not released or absorbed from food. 4

But what if serum folate and B12 levels return as normal in our patient with macrocytosis? It turns out that alcohol consumption, independent of folate or B12 deficiency, may also cause macrocytosis. 5 Though the exact mechanism is unknown, it may be related to alcohol’s direct toxicity or that of its metabolites; alcohol is oxidized to acetaldehyde, which affects membranes of red blood cells (RBCs) and their precursors by forming adducts with erythroid proteins,6 and interfering with cell division.7 Interestingly, alcohol-related macrocytosis may appear before anemia is detected and can resolve within 2-4 months of abstinence.

In addition to alcohol, cirrhosis itself may be associated with macrocytic anemia caused by lipid deposition on RBC membranes.1

See also a related pearl at  www.Pearls4Peers.com

References

  1. Hoffbrand V, Provan D. ABC of clinical haematology: macrocytic anaemias. BMJ 2011;314(7078):430–430. https://www.ncbi.nlm.nih.gov/pubmed/9040391
  2. Medici V, Halsted CH. Folate, alcohol, and liver disease. Mol Nutr Food Res 2013;57(4):596–606. https://www.ncbi.nlm.nih.gov/pubmed/23136133
  3. Bode C, Bode CJ. Effect of alcohol consumption on the gut. Best Pract Res Clin Gastroenterol [Internet] 2003;17(4):575–92. https://www.sciencedirect.com/science/article/pii/S1521691803000349
  4. Dali-Youcef N, Andrès E. An update on cobalamin deficiency in adults. QJM 2009;102(1):17–28. https://academic.oup.com/qjmed/article/102/1/17/1502492
  5. Savage DG, Ogundipe A, Allen RH, Stabler SP, Lindenbaum J. Etiology and diagnostic Evaluation of macrocytosis. Am J Med Sci [Internet] 2000;319(6):343–52. http://dx.doi.org/10.1016/S0002-9629(15)40772-4 https://www.ncbi.nlm.nih.gov/pubmed/10875288
  6. Latvala J, Parkkila S, Melkko J, Niemelä O. Acetaldehyde adducts in blood and bone marrow of patients with ethanol-induced erythrocyte abnormalities. Mol Med 2001;7(6):401–5. https://www.ncbi.nlm.nih.gov/pubmed/11474133
  7. Wickramasinghe SN, Malik F. Acetaldehyde causes a prolongation of the doubling time and an increase in the modal volume of cells in culture. Alcohol Clin Exp Res 1986;10(3):350–4. https://www.ncbi.nlm.nih.gov/pubmed/3526962

 

Contributed by Kim Schaefer, Harvard medical student, Boston, MA

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Why does my patient with alcoholic cirrhosis have macrocytic anemia?

What is the significance of teardrop cells (dacrocytes) on the peripheral smear of my patient with newly-discovered pancytopenia?

FA Manian MD, MPH, , , , , , , , , , , , , , , , , Leave a comment

The presence of teardrop cells (dacrocytes) (Figure below) in the peripheral blood, named for their tear drop shape, is a prominent feature of myelophthisic (marrow infiltrative) conditions, including myelofibrosis, hematologic malignancies, cancer metastatic to the bone marrow, and granulomatous diseases. Teardrop cells may also be seen in beta-thalassemia, autoimmune and microangiopathic hemolytic anemia and severe iron deficiency (1-4).

 
When evaluating patients with leucoerythroblastic smears (defined by the presence of early myeloid and erythroid forms), the presence of teardrop cells can be helpful in distinguishing often malignant marrow infiltrative conditions from a benign reactive process.  Conditions where teardrop cells are seen with high frequency may also have extramedullary hematopoiesis, particularly in the spleen (1,2).
The mechanism of teardrop cell formation may be multifactorial but appears to involve distortion of the red cells as they pass through marrow or splenic sinusoids.

 

Teardrop cells resulting from conditions such as cancer metastatic to the bone marrow likely involve primarily a marrow origin of the cells whereas primary myelofibrosis with prominent extramedullary hematopoiesis include a splenic mechanism of teardrop cell formation (2).

 
Supporting the possible splenic contribution to teardrop cell formation is the observation that teardrop cells may be reduced in number or eliminated entirely after splenectomy in patients with myelofibrosis and autoimmune hemolytic anemia (1,4).

Teardrop

Figure. Teardrop cells

References

1. DiBella NJ, Sliverstein MN, Hoagland HC. Effect of splenectomy on teardrop-shaped erythrocytes in agnogenic myeloid metaplasia. Arch Intern Med 1977; 137: 380-381. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/586447
2. Gutgemann I, Heimpel H, Nebe CT. Significance of teardrop cells in peripheral blood smears. J Lab Med 2014; DOI: 10.1515/labmed-2014-0005 https://www.researchgate.net/publication/272430111_Significance_of_teardrop_cells_in_peripheral_blood_smears
3. Korber C, Wolfler A, Neubauer M, Robier Christoph. Red blood cell morphology in patients with β-thalassemia minor. J Lab Med 2016-12-10 | https://www.researchgate.net/publication/311564128_Red_blood_cell_morphology_in_patients_with_b-thalassemia_minor DOI: https://doi.org/10.1515/labmed-2016-0052
4. Robier C, Klescher D, Reicht G,Amouzadeh-Ghadikolai O, Quehenberger F, Neubauer M. Dacrocytes are a common morphologic feature of autoimmune and microangiopathic haemolytic anaemia. Clin Chem Lab Med. 2015;53:1073-6. https://www.ncbi.nlm.nih.gov/pubmed/25503671

Contributed by Tom Spitzer, MD, Director of Cellular Therapy and Transplantation Laboratory,  Massachusetts General Hospital, Boston, MA.

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What is the significance of teardrop cells (dacrocytes) on the peripheral smear of my patient with newly-discovered pancytopenia?

Should I order a blood transfusion based on the hemoglobin (Hgb) or the hematocrit (Hct)?

FA Manian MD, MPH, , , , , , , , Leave a comment

Despite the frequent interchangeability of Hgb (g/dL) and Hct (%) by a ratio of ~1:3, directly-measured blood Hgb levels may be preferred for assessing the need for blood transfusion for at least 3 reasons:

First, in contrast to the widely-used automated measurements of Hct, Hgb is not affected by conditions that affect the size of the RBCs or the mean corpuscular Hgb concentration (MCHC). This is because the Hct is not a direct measure of Hgb; rather it’s the proportion of blood occupied by RBCs which, in automated systems, is derived by multiplying the number of RBCs by the mean corpuscular volume (MCV).1-3

This may not be a significant issue when MCHC is normal, but when MCHC is abnormal, HCT may not accurately reflect the blood Hgb concentration. For example, in patients with hypochromic iron deficiency anemia with RBCs containing less hemoglobin (ie, low MCHC), the Hct may overestimate blood Hgb levels. Conversely in hereditary spherocytosis with its attendant low RBC volume and high MCHC, the Hct may underestimate Hgb levels.

Second, Hct results may also be more subject to technical factors in the lab. For example, blood at room temperature between 6-24 h may be associated with RBC swelling and increased Hct without any change in its Hgb concentration.4

Finally, national and international guidelines on blood transfusion generally target Hgb, not Hct results.5-7

For a related pearl, go to https://pearls4peers.com/2016/11/01/should-i-use-a-hemoglobin-level-of-7-or-8-gdl-as-a-threshold-for-blood-transfusion-in-my-hospitalized-patient.

 

References

  1. Tefferi A, Hanson CA, Inwards DJ. How to interpret and pursue an abnormal complete blood cell count in adults. Mayo Clin Proc 2005;80:923-36. https://www.ncbi.nlm.nih.gov/pubmed/16007898
  2. Macdougall IC, Ritz E. The Normal Haematocrit Trial in dialysis patients with cardiac disease: are we any the less confused about target hemoglobin? Nephrol Dial Transplant 1998;13:3030-33. https://academic.oup.com/ndt/article-pdf/13/12/3030/9907456/3030.pdf
  3. Kelleher BP, Wall C, O’Broin SD. Haemoglobin, not haematocrit, should be the preferred parameter. Nephrol Dial Transplant 2001;16:1085-87. https://www.ncbi.nlm.nih.gov/pubmed/11328933
  4. Hayuanta HH. Can hemoglobin-hematocrit relationship be used to assess hydration status? CDK-237/vol 43 no.2, th. 2016 http://www.kalbemed.com/Portals/6/20_237Opini-Can%20Hemoglobin-Hematocrit%20Relationship%20Be%20Used%20to%20Assess%20Hydration%20Status.pdf
  5. Blood transfusion. NICE guideline, November, 2015. https://www.nice.org.uk/guidance/ng24/chapter/Recommendations#fresh-frozen-plasma-2 uk
  6. National Blood Authority: Australia. Patient blood management, November 2016. https://www.blood.gov.au/system/files/documents/nba-patient-blood-management-resource-guide-nov_2016_v3_sm_web_file.pdf
  7. Carson JL, Guyatt G, Heddle NM, et al. Clinical practice guidelines from the AAABB: red blood cell transfusion thresholds and storage. JAMA 2016; 316:2025-2035. https://www.ncbi.nlm.nih.gov/pubmed/27732721

 

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Should I order a blood transfusion based on the hemoglobin (Hgb) or the hematocrit (Hct)?