Blood

Authors: Flaherty, Alice W.; Rost, Natalia S.

Title: Massachusetts General Hospital Handbook of Neurology, The, 2nd Edition

Copyright 2007 Lippincott Williams & Wilkins

> Table of Contents > Medicine > Blood

Blood

A. Anemia

• Neurological complications of anemia: Lightheadedness, HA; sickle cell anemia can cause strokes, seizures, or extramedullary hematopoiesis in the meninges that mimics masses.

• H&P: H/o ulcers, liver dz, easy bleeding, ecchymoses, stool guaiac, jaundice, adenopathy.

• Tests: CBC, BUN/Cr. Consider reticulocyte count, smear for morphology, iron, TIBC, ferritin, bilirubin, endoscopy or abdominal CT, SIEP, Hb electrophoresis, haptoglobin, Coombs test, bone marrow biopsy.

• Causes of anemia:

  • Acute: Bleeding

  • Subacute:

    • Normal haptoglobin and bilirubin: Bleeding.

    • Low haptoglobin, high unconjugated bili: Hemolysis (antibody-mediated, traumatic, toxic, intrinsic cell defect).

  • Chronic:

    • Low reticulocyte count (decreased production):

      • Low MCV (microcytic):

        • Iron deficiency: Fe and ferritin down, TIBC up. Usually from bleeding. Consider endoscopy. Treat with ferrous sulfate 325 mg tid if Fe/TIBC ratio is <20%.

        • Anemia of chronic dz: Fe down, ferritin up (only if ESR is up), TIBC down.

        • Others: Thalassemia, sideroblastic anemia.

      • Normal MCV (normocytic): Bone marrow failure (aplastic anemia), either secondary (kidney, liver, or other chronic dz) or primary.

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      • High MCV (macrocytic): B₁₂ or folate deficiency, drug-induced, liver dz, hypothyroidism.

    • High reticulocyte count (increased production): Bleeding, hemolysis. See subacute anemia on page 204.

• Rx of acute or severe anemia: Blood bank sample, type and cross 2 units, guaiac stools, consider transfusion, gastric lavage. For active bleeding, place two 14-gauage IVs, start saline, consider medicine or GI consult.

  • Bleed on anticoagulants: Reverse anticoagulation. see p. 161.

  • Transfusions: 1 unit packed red blood cells (PRBC) should raise Hct 3 points.

    • Typical transfusion order: Transfuse 2 U PRBC over 4 h each; premed before each unit with acetaminophen 650 mg PO and diphenhydramine 50 mg PO.

    • If severe anemia or danger of CHF: Premedicate with 20 mg furosemide IV before each unit.

    • If danger of transfusion reaction: E.g., if pt. has received many transfusions, request leukopoor or washed RBCs.

    • If pt. has suppressed marrow: Use irradiated RBCs.

  • Transfusion reaction: Call blood bank.

    • H&P: Sudden fever (most common), sweating, hives, wheezing, tachycardia, hypotension.

    • Rx: Stop blood product. Diphenhydramine and acetaminophen if mild. If severe, add hydrocortisone 50-100 mg IV. If hemolysis, maintain diuresis with IV fluids and furosemide.

B. Coagulopathy

• Neurological complications of coagulopathy: Stroke, hemorrhage, HA, lightheadedness, neuropathy (especially femoral, from retroperitoneal bleed). Paraprotein can cause neuropathy.

• H&P: Look for hematomas, signs of liver or autoimmune dz, tumor.

• Tests: Check plts, PT, PTT, fibrinogen, D-dimer, protein C and S (cannot be tested on warfarin), antithrombin III (cannot be tested on heparin), anticardiolipin Ab, lupus anticoagulant, ESR, RF, ANA.

• Causes of abnormal coagulation:

  • Long PTT: Heparin, anticardiolipin Ab, lupus anticoagulant, intrinsic pathway defect, hemophilia, DIC.

  • Long PT: Warfarin, vitamin K deficiency, liver dz, DIC, extrinsic pathway defect.

  • Long PT and PTT: Very high levels of warfarin; common pathway defect, some lupus anticoagulant.

  • Hypercoagulable states: DIC, tumors, pancreatitis, vasculitis, oral contraceptives, smoking, DM, nephrotic syndrome, anticardiolipin Ab, lupus anticoagulant, homocystinuria, thrombocytosis, leukostasis. Deficiency of protein C, activated protein C, protein S, or antithrombin III.

• Anticoagulants: see p. 160.

• Antibody-mediated coagulation disorders (antiphospholipid syndrome):

  • Criteria: 1 each of clinical and laboratory criteria:

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    • Clinical: Stroke or other vascular thrombosis in any location, or complication of pregnancy.

    • Laboratory: Anticardiolipin IgG or IgM antibodies at moderate-high levels, or lupus anticoagulant antibodies detected on 2 occasions 6 wk apart.

  • Other sx: Thrombocytopenia, hemolytic anemia, or livedo reticularis.

  • Arterial vs. venous clots: Pts. who have had one or the other tend to continue to have that kind. Most common thrombosis is DVT, but most common arterial-side clot is stroke.

  • PTT: Normal or high, as these antibodies have anticoagulant as well as procoagulant effects.

  • Cause: Primary or secondary (to autoimmune disease, primarily SLE).

  • Rx: A thrombotic event is an indication for anticoagulation See Anticoagulants, p. 160, for contraindications. Coumadin goal is INR 2-3. Because these Abs can falsely raise PTT, heparinoids should be measured using anti-factor Xa levels.

C. DIC (disseminated intravascular coagulation)

Often post-op, or from sepsis. Platelets and fibrinogen are low; PT, PTT, and D-dimer are high.

• Rx of DIC: Treat underlying cause; if necessary, replace with fresh frozen plasma, platelets, cryoprecipitate, blood. Heparin is usually not indicated, unless there is evidence of thrombosis (e.g., stroke, digit ischemia, or oliguria despite good SBP) or in some malignancies. Never give heparin if there has been head trauma.

D. Erythrocyte sedimentation rate (ESR)

Nonspecific but useful to rule out temporal arteritis, cancer, chronic infection.

• Normal ESR for women = (age)/2 + 10.

• Normal ESR for men = (age)/2.

E. Eosinophilia

Mnemonic for causes is NAACP : Neoplasm, Addison's dz, Allergy, Collagen vascular dz, Parasites.

F. Heparin-induced thrombocytopenia (HIT)

• H&P: Platelets fall while pt. is receiving heparin; also associated with venous or arterial thrombosis.

• Dx: Blood ELISA for heparin bound to platelet factor 4 (HIT test, sensitive but not specific).

• Rx: Permanently discontinue heparin (including low molecular weight). Change to argatroban, danaparoid, or hirudin if further anticoagulation is needed. (See Anticoagulants, p. 160.)

G. Platelet disorders

• Neurological complications of platelet problems: See Coagulopathy, p. 192.

• H&P: NSAID or heparin use? HIV? Look for petechiae, mucous membrane bleeding.

• Tests: Consider bleeding time, von Willebrand's factor test, HIV.

• Contraindications: If plts <100: no surgery. Plts <50: no minor procedures. Plts <20: bleed from minor trauma. Plts <10: spontaneous bleeding (except in idiopathic thrombocytopenic purpura, where remaining plts are hyperactive).

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• Causes: DIC, drug reaction (e.g., HIT) idiopathic thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), SLE, HIV.

• Rx: Try Amicar, DDAVP. Autoimmune problem may be helped with steroids, IgG, pheresis. Think twice about platelet transfusion in DIC, ITP, or TTP, where pt. may be hypercoagulable, and in autoimmune or drug-induced platelet dysfunction, where platelet transfusion probably will not help.

H. Thrombotic thrombocytopenic purpura

• H&P: Low platelets, microangiopathic hemolytic anemia, altered mental status (often with seizures); fever, renal problems.

• Rx: Pheresis.