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Anemia in Hypothyroidism

Discussion in 'Endocrinology' started by neo_star, Jan 23, 2013.

  1. neo_star

    neo_star Moderator

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    [FONT=&amp]Anemia in Hypothyroidism


    ....of unknown origin has many examples in medicine and is notorious in giving doctors a bad reputation.
    One such example is anemia of unknown origin....I mean u ruled out Meckel's, occult bleeding from peptic ulcer, colon cancer, worm infestation, kidney disease, the leukemias, marrow failure, pernicious anemia, checked for G 6 P D and may be in our enthusiasm a course of Primaquine to weed out any hidden ovale or vivax that could be tking a stroll every once in a while.... etc. ( end of thinking capacity ) and still no clue about it's cause.

    i came
    across hypothyroidism as one of the causes in a few places and decided to put it together.






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    [FONT=&amp]Anemias are diagnosed in 20-60% patients with hypothyroidism. [/FONT][FONT=&amp]

    Real values of the degree of anemia are estimated by radioisotopic analysis due to the lower volume of plasma in hypothyroidism causing false high levels of hemoglobin in blood.

    Anemia is often the first sign of hypothyroidism.

    Diagnosis of hypothyroidism should be considered in every case of anemia with uncertain etiology because sometimes signs of overt hypothyroidism needn't necessarily be evident. Microcytic, macrocytic and normocytic are regularly described anemias.

    CLASSIFICATION: ( various types of anemia encountered in hypothyroidism )

    a) Microcytic anemia
    is usually ascribed to malabsorption of iron and loss of iron by menorrhagia.

    b) Macrocytic anemia is caused by malabsorption of vitamin B12, folic acid, pernicious anemia and inadequate nutrition.
    Pernicious anemia occurs 20 times more frequently in patients with hypothyroidism than generally.

    Macrocytosis is found in up to 55% patients with hypothyroidism and may result from the insufficiency of the thyroid hormones themselves without nutritive deficit.

    c) Normocytic anemia, so-called uncomplicated anemia, arises due to thyroid hormones deficit itself not followed by nutritive deficit. This type of anemia is considered to be an adaptation to a decreased basal metabolism. Thyroid hormones directly or indirectly, through erythropoietin, stimulate growth of erythroid colonies (BFU-E, CFU-E). Normocytic anemia is characterized by reticulopenia, hypoplasia of erythroid lineage, decreased level of erythropoietin, mainly regular erythrocyte survival.

    Acanthocytosis findings in cytologic blood smear suggest hypothyroidism in about 90% of cases.

    Refrence[/FONT][FONT=&amp] [Anemia in hypothyroidism]. [Med Pregl. 1999 Mar-May] - PubMed - NCBI[/FONT]
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    Hypothyroidism Causing Macrocytic Anemia Unresponsive to B12 and Folat[/FONT]
    [FONT=&amp]e[/FONT][FONT=&amp]

    A patient with pernicious anemia who developed a mild macrocytic anemia after many years of monthly vitamin B12 therapy is presented. There was no response to the addition of folic acid and multivitamins. Evaluation for causes of elevated mean corpuscular volume and consideration of associated autoimmune disorders led to the diagnosis of primary hypothyroidism. Treatment with levothyroxine led to correction of the hematologic abnormalities over a four-month period. The anemia of hypothyroidism may present with macrocytic indices and this diagnosis should be suspected when this finding is noted.

    Refrence[/FONT][FONT=&amp] Hypothyroidism Causing Macrocytic Anemia Unresponsive to B12 and Folate[/FONT]
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    Patients with a variety of endocrine disorders that produce lower metabolic rates may develop a mild to moderate hypoproliferative anemia. The release of EPO from the kidney is sensitive to the need for O2, not just O2 levels, Thus EPO productios is triggered at lower levels of O2 tension in disease states (such ad hypothyroidism and starvation) where metabolic activity, and thus O2 demand, is decreases.

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    [FONT=&amp]Reference: [/FONT][FONT=&amp]Harrisons Principles of Internal Medicine, 18th Edition[/FONT][FONT=&amp] Chapter 103: Iron defiency and other hypoproliferative anemias : ANEMIA IN HYPOMETABOLIC STATES[/FONT]
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    In a nutshell

    1) always include hypothyroidism in your differentials of anemia of unknown etiology or anemia unresponsive to multivitamins and iron.

    2) The blood picture in hypothyroidism could be confusing
    If u have Hashimoto's and pernicious then mostly megaloblastic anemia.
    If hypothroidism and heavy menstural cycles then microcytic anemia.
    If uncomplicated hypothyroidism then mostly normocytic, normochromic anemia (due to decreased EPO levels)[/FONT]
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