Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content ++ RBC ↓, evidenced by hemoglobin (Hb) (<13.5g/dL ♂, <12g/dL ♀) or hematocrit (Hct) (<41% ♂, <36% ♀)Expert opinions vary on precise definition of anemia; Hb & Hct are volume dependent +++ 3 Primary Etiologies ++ Blood loss: trauma, menstruation, GI bleeding (NSAIDs), blood donation, parasitesInadequate RBC production: nutritional deficiency (B12, folate, iron), endocrine abnormalities (thyroid, EPO, hypogonadism), malignancy, etc.RBC destruction: hemolysis—genetic or acquired +++ Classification Based on Average RBC Size ++Figure 21-1.Graphic Jump LocationView Full Size|Favorite Figure|Download Slide (.ppt)Morphology of anemia. ++ Signs/symptoms: result of impaired O2 delivery to tissues; perfusion can be maintained down to ∼Hb 8–9g/dL Fatigue, SOB/DOE, palpitations, headache, confusion, mental slowing, change in stool habits (GI bleeding), tachycardia, hypotension, pallor, splenomegaly, jaundiceInitial evaluation: Hb/Hct, MCV, RDW, reticulocyte count, WBC, platelet count, peripheral smear Macrocytic anemia: B12 & folate deficiencies; result in indistinguishable anemias B12 deficiency: RDA 2.4mcg/d—macrocytosis can precede anemia by several monthsComplications: myelopathy, ataxia, paresthesia, loss of proprioception & vibratory sensation, cognitive impairment, confusion, depression, psychosis, osteoporosisEfficient use of B12 requires a working gut, gastric acid & pepsin to free B12 from food proteins in the gut, & intrinsic factor (IF) to facilitate absorption in the ileum Pernicious anemia (PA) (loss of intrinsic factor) is common cause of B12 deficiency; ∼1% of ingested B12 is passively absorbed without IFTypical diet provides adequate B12; most Americans ≥2–5y of stores (highly conserved) (Neurology 1995;45:1435) At risk: elderly (achlorhydria, dietary deficiency), strict vegetarians/vegans, GI disease/surgery, pancreatic insufficiency, PPI use, metformin use (South Med J 2010;103:265)Causes functional folate deficiency (folate trap)B12 serum concentrations vary with age & gender, making it less than optimal for determining deficiency (Food & Nutrition Bulletin 2008;29:S67) Accumulation of methylmalonic acid (MMA) specific to B12 deficiency Fasting urine MMA 99% specific for diagnosing B12 deficiency (Ann Intern Med 1987;106:707); serum MMA affected by renal status (Clin Chem 2000;46:1277)Folate deficiency: RDA 400mcg/d—associated with hyperhomo–cysteinemia & periconceptually with neural tube defects (Lancet 1997;350:1666) RBC folate: may be more reliable indicator of deficiency than serum folate in acutely ill → serum levels susceptible to dietary change, while RBC levels reflect span of RBC life (Am J Clin Nutr 2011;94:303S); both ↑ with age (J Nutr 2006;136:153); this may make interpreting results problematicHomocysteine accumulates in B12 & folate deficiencies; serum homocysteine concentration may be a better indicator of folate deficiency than direct folate measurements (JAMA 1993;270:2693)Microcytic anemia: iron-deficiency anemia (IDA) Iron RDA: ♂ & postmenopausal ♀ ∼8mg/d; menstruating ♀∼18mg/d No mechanism for excretion ∴ regulated by GI tract absorption (↓); heme iron (animal source) absorbed better than nonheme (plant source)Serum iron sensitive to daily intake; diurnal variation (Am J Clin Pathol 2002;117:802)Ferritin: best indicator of IDA (J Nutr 2005;135:1974); acute phase reactant; ↑ with ... GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of AccessPharmacy 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value AccessPharmacy Full Site: One-Year Individual Subscription $595 USD Buy Now View All Subscription Options