UNDERSTANDING LAB RESULTS

LAB RESULTS REVIEW

I took some notes on most common labs. Email me if you have any others to add. 

—ABG

—pH – normal 7.35-7.45

¡Increased (metabolic alkalosis – hypokalemia, hypochloremia, chronic vomiting) (respiratory alkalosis – heart failure, CO poisoning, shock, pain, anxiety)

¡Decreased (metabolic acidosis – ketoacidosis, lactic acidosis, severe diarrhea) (respiratory acidosis – respiratory failure)

—PCO2 – normal 35-45 mmHg

¡Increased – COPD, head trauma, oversedation

¡Decreased – hypoxemia,pe, anxiety, pain, pregnancy

—HCO3 – normal 21-28 mEq/L

¡Increased – chronic vomiting, COPD

¡Decreased – chronic diarrhea, starvation, DKA, ARF

—PO2 – normal 80-100 mmHg

—O2 saturation – normal 95-100%

—O2 content – arterial 15-22 vol %, venous 11-16 vol %

—AMYLASE/LIPASE

—Lipase

¡Normal 0-160 units/L

¡Most commonly elevated with acute pancreatitis

¡Enzyme secreted by pancreas into duodenum to break down triglycerides into fatty acids

¡More specific

¡May be elevated in patients with renal failure

—Amylase

¡Normal 30-220 units/L

¡Aids catabolism of carbohydrates to simple sugars

¡Rise within 12 hours of onset of disease, then return to normal in 48-72 hours

¡Sensitive but not specific for pancreatic disease

¡Increased – acute pancreatitis, perforated peptic ulcer, necrotic/perforated bowel, acute cholecystitis

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ANA

—Antinuclear antibodies

—Used to diagnosis SLE and other autoimmune

—ANA positive in 95% patients with SLE, negative ANA excludes SLE

—Can be positive with ANA, Sjogren’s, scleroderma, RA, Raynaud’s, autoimmune thyroiditis, etc

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PT/INR

—PT/INR

¡PT normal 11.0-12.5 seconds

¡INR 0.8-1.1

¡Evaluates extrinsic system and common pathway

÷Measures clotting ability of factor I (fibrinogen), II (prothrombin), V, VII, X

¢PT prolonged when these are deficient

¢Ex: cirrhosis, hepatitis – because factors I, II, V, VII, IX, X produced in liver

¢Ex: obstructive biliary disease – vitamins A, E, D, K not absorbed and synthesis of factor II, VII, IX, X depends on vitamin K

¢Ex: coumarin use – interfere with production of vitamin K dependent factors

¡Preferred INR

÷DVT prophylaxis 1.5-2.0

÷Orthopedic surgery 2.0-3.0

÷DVT 2.0-3.0

÷A-fib 2.0-3.0

÷PE 2.5-3.5

÷Prosthetic valve prophylaxis 3.0-4.0

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PTT

—Normal 60-70 seconds

—Assess intrinsic system and common pathway

—Evaluates factors I (fibrinogen), II (prothrombin), V, VIII, IX, X, XI, XII

—Prolongs PTT

¡Hemophilia – factors inadequate

¡II, IX, X are vitamin K dependent – biliary obstruction

¡Liver disease – because factors made in liver

¡Heparin – inactivates prothrombin (factor II) and prevents formation of thromboplastin

÷Immediate and short lived effect

—HGA1C

—Glycosylated hemoglobin

—98% hemoglobin in adult RBC is hemoglobin A

—7% hemoglobin A consists of HbA1 which combines strongly with glucose

—Reflects blood glucose level over past 120 days

—A1c 4 = 65 mg/dl

—A1c 5 = 100 mg/dl

—A1c 6 = 135 mg/dl

—A1c 7 = 170 mg/dl

—A1c8 = 205 mg/dl

—ADA goal < 7%

—

BILIRUBIN

—Normal adult

¡Total 0.3-1.0 mg/dl

¡Indirect 0.2-0.8 mg/dl

¡Direct 0.1-0.3 mg/dl

—RBC breakdown à hemoglobin released and broken down to heme and globin à heme catabolized to biliverden which is transformed to bilirubin (unconjugated (indirect) bilirubin)

—Indirect bilirubin conjugated with glucuronide causing conjugated (direct) bilirubin

—Jaundice when exceeds 2.5 mg/dl

—Increased conjugated (direct) bilirubin

¡Gallstones, extrahepatic duct obstruction, liver metastasis

—Increased unconjugated (indirect) bilirubin

¡Hemolytic jaundice, hepatitis, sepsis, hemolytic anemia, cirrhosis, pernicious anemia, sickle cell anemia

—

B12

—Cyanocobalamin

—Converts inactive form of folate to active form

—Normal 160-950 pg/ml

—Serum B12 – recent B12 ingestion

—Urinary methylmalonic acid – prolonged B12 deficiency

—Deficiency – pernicious anemia, malabsorption syndromes, IBD, ZES, pregnancy, vitamin C deficiency, folic acid deficiency

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BLOOD TYPE

—BLOOD ALCOHOL

—> 80mg/dl – flushing, slowing of reflexes, impaired visual activity

—80 mg/dl = .08

—Elevated blood ketones (DKA) can cause false elevation

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BMP/CMP

—BMP (8 tests)

¡(kidneys, blood sugar, electrolyte, acid/base)

÷Glucose

÷Calcium

÷Sodium

÷Potassium

÷CO2

÷Chloride

÷BUN

÷Creatinine

—CMP

¡ (14 tests) – kidneys, liver, electrolytes, acid/base, blood sugar, proteins

÷Glucose

÷Calcium

÷Albumin

÷Total protein

÷Sodium

÷Potassium

÷CO2

÷Chloride

÷BUN

÷Creatinine

÷ALP

÷ALT

÷AST

÷Bilirubin

—BUN/CREATININE

—BUN

¡Evaluate kidney function

¡Increased – impaired kidney function or from decreased blood flow to kidneys (CHF, shock, stress, recent MI, severe burns) or obstruction of urine flow (dehydration)

÷Also with excessive protein breakdown, high protein diet, GI bleed (proteins in blood)

¡Decreased – not common

÷Severe liver disease, malnutrition, overhydration

¡May see decreased or increased BUN during normal pregnancy

—Creatinine

¡Evaluate kidney function

¡Waste product produced in muscles from breakdown of creatine

¡Increased – blood vessel swelling (glomerulonephritis), pyelonephritis, acute tubular necrosis, prostate disease, kidney stone (or other obstruction), reduced flow (shock, dehydration, CHF, atherosclerosis, diabetes)

¡Can increase temporarily due to muscle injury or pregnancy

¡Decreased – not common, conditions with decreased muscle mass

¡

—BNP

—Brain natriuretic peptide

—To evaluate severity of CHF

—BNP – produced primarily by left ventricle, small amounts continuously produced by heart

¡When left ventricle stretched, can increase greatly = heart is working harder

—BNP can increase with age and kidney disease

—CARDIAC ENZYMES

—CRP

¡Made in the liver and secreted into blood

¡Increases with inflammation and infection – ex MI, surgery, trauma

—CK

¡Enzyme found in heart, brain, skeletal muscle, etc

¡Level rises when muscle cells are injured

¡Begins to rise 4-6 hours after heart attack, highest in 18-24 hours, back to normal in 2-3 days

—CK-MB

¡Separate form of CK - Found mostly in the heart

¡Detected 3-4 hours after onset of chest pain, peaks in 18-24 hours, returns to normal within 72 hours

¡If CK-MB elevated and ratio of CK-MB to total CK is more than 2.5-3 then it is likely that heart was damaged

—TROPONIN

¡Proteins found in skeletal and heart muscle

¡Troponin C, T, I

¡I and T found only in the heart – normally present in small undetectable quantities

¡Elevated 3 hours after injury, Can remain high for 1-2 weeks

—MYOGLOBIN

¡Oxygen binding protein found in the heart and skeletal muscles

¡Released into blood with heart or muscle damage

¡Start to rise within 2-3 hours of injury, highest level 8-12 hours, back to normal within 1 day

¡Increase indicates very recent injury

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CBC WITH DIFFERENTIAL (1 OF 3)

—WBC – normal 5000-10,000

¡NEUTROPHILS (normal – 55-70%) (granulocyte)

÷Exist in circulation for only 6 hours, phagocytosis - BACTERIAL

÷POLYS -

÷SEGS

÷BANDS – immature neurophils (shift to the left)

¡LYMPHOCYTES (normal – 20-40%) – T (cellular type immunity) and B cells (antibody) – CHRONIC BACTERIA AND ACUTE VIRAL

¡MONOCYTES (normal – 2-8%) – fight bacteria like neutrophils but produced more rapidly and spend more time in circulation

¡EOSINOPHILS (normal - 1-4%) (granulocyte) - ALLERGIC

¡BASOPHILS (normal – 0.5-1%) (granulocyte) mast cells - ALLERGIC

—RBC – male normal 4.7-6.1, female normal 4.2-5.4

¡Number of circulating RBC in 1 mm3 of peripheral venous blood

¡Increased – high altitude, polycythemia vera, dehydration, thalassemia

¡Decreased – hemorrhage, hemolysis, anemia, leukemia, advanced CA, MM, pernicious anemia, RA, pregnancy, dietary deficiency, renal failure, chronic disease

—HGB – normal male 14-18 g/dl, normal female 12-16 g/dl

¡Total amount of hemoglobin in peripheral blood

¡Hemoglobin – vehicle for CO2 and oxygen

¡Increased – congenital heart disease, polycythemia vera, COPD, CHF, high altitudes, severe burns, dehydration

¡Decreased – anemia, hemorrhage, hemolysis, nutritional deficiency, lymphoma, SLE,  sarcoidosis, kidney disease, chronic hemorrhage, splenomegaly, neoplasm

—HCT – normal male 42-52%, normal female 37-47%

¡Measure of percentage of total blood volume that is made up of RBCs

¡Increased – congenital heart disease, polycythemia vera, severe dehydration, eclampsia, erythrocytosis, burns, COPD

¡Decreased – anemia, hyperthyroidism, cirrhosis, hemorrhage, dietary deficiency, bone marrow failure, normal pregnancy, RA, MM, leukemia, hemoglobinopathy

—MCV – mean corpuscular volume – normal 80-95 um3

¡Average volume/size of single WBC

—MCH – mean corpuscular hemoglobin – normal 27-31 pg

¡Average amount (weight) of hemoglobin within RBC

—MCHC – mean corpuscular hemoglobin concentration – normal 32-36 g/dl

¡Average concentration or percentage of hemoglobin within a single RBC

—RDW – red blood cell distribution width – normal 11-14.5%

¡Indication of variation in RBC size

—PLATELET COUNT – normal 150,000-400,000/mm3

¡Increased (thrombocytosis) – malignant disorder, polycythemia vera, RA, iron deficiency anemia

¡Decreased (thrombocytopenia) – hypersplenism, hemorrhage, leukemia, thrombocytopenia, DIC, SLE, pernicious anemia, hemolytic anemia, chemotherapy, infection)

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—ANEMIA ACCORDING TO RBC INDICES

—NORMOCYTIC (normal size RBC), NORMOCHROMIC (normal color)

¡Iron deficiency (early), chronic illness, acute blood loss, aplastic anemia, acquired hemolytic anemia

—MICROCYTIC (smaller than normal RBC), HYPOCHROMIC (less than normal color)

¡Iron deficiency (late), thalassemia, lead poisoning

—MICROCYTIC, NORMOCHROMIC

¡Renal disease

—MACROCYTIC (larger than normal RBC), NORMOCHROMIC

¡Vitamin B12 or folate deficiency, chemotherapy, myeloid leukemia, ethanol toxicity, thyroid dysfunction

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D-DIMER

—Normal <250-600 ng/ml

—Assesses thrombin and plasmin activity

—Fibrin degradation fragment that is made through lysis of cross linked fibrin

—As plasmin acts on fibrin polymer clot, fibrin degradation products and D-dimer are produced

—Increased – fibrinolysis, DVT, PE, therapy with TPA, arterial thromboembolism, DIC, sickle cell anemia, pregnancy, malignancy, surgery

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—ELECTROLYTES

—Mg

¡1.3-2.1 mEq/L

¡Most intracellularly, half in bone, most bound to ATP

¡Low – can cause cardiac irritability and aggravate cardiac arrhythmias

¡Increased – renal insufficiency, uncontrolled DM, Addison’s disease, hypothyroidism, ingestion of Mg containing antacids

¡Decreased – malnutrition, malabsorption, hypoparathyroidism, alcoholism, chronic renal disease, diabetic acidosis

—P

¡3.0-4.5 mg/dl

¡Increased – renal failure, increased intake, acromegaly, hypoparathyroidism, bone metastatis, sarcoidosis, hypocalcemia, liver disease, acidosis, hemolytic anemia

¡Decreased – inadequate ingestion, chronic antacid ingestion, hyperparathyroidism, hypercalcemia, chronic alcoholism, vitamin D deficiency, diabetic acidosis, rickets, osteomalacia, malnutrition, alkalosis, sepsis

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ESR

—Erythrocyte Sedimentation Rate

¡Normal – male up to 15 mm/hr, female up to 20 mm/hr

¡Rate with which RBC settle in saline or plasma over specific time

¡Not specific - RBC have tendency to stack up on one another, increasing their weight and causing them to settle faster

¡Increased – chronic renal failure, malignant disease, bacterial infection, inflammatory diseases, necrotic tissue diseases, hyperfibrinogenemia, macroglobulinemia, severe anemias

¡Decreased – sickle cell anemia, spherocytosis, hypofibrinogenemia, polycythemia vera

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B-HCG

—Human chorionic gonadotropin

—Qualitative – urine

—Quantitative – blood

¡< 1 week   5-50

¡2  50-500

¡3  100-10,000

¡4  1000 – 30,000

¡5  3500-115,000

¡6-8  12,000-270,000

¡12  15,000-220,000

¡Not pregnant <5

—HCG secreted by placental trophoblast after ovum fertilized

—Will appear in blood or urine as early as 10 days after conception

—IRON/TIBC/TRANSFERIN

—Iron

¡Normal male 80-180mcg/dl, female 60-160mcg/dl

¡30% stored in form of ferritin and hemosiderin

¡Bound to protein transferrin

¡Increased – hemosiderosis, hemochromatosis, hemolytic anemia, hepatitis, lead toxicity, iron poisoning, massive transfusion

¡Decreased – insufficient dietary iron, chronic blood loss, inadequate absorption of iron, pregnancy, iron deficiency anemia, neoplasia, chronic GI bleed, chronic hematuria, chronic heavy menstruation

—TIBC

¡normal 250-460 mcg/dl

¡Measurement of all proteins available for binding mobile iron

¡Increased – oral contraceptives, pregnancy, polycythemia vera, iron deficiency anemia

¡Decreased – hypoproteinemia, inflammatory diseases, cirrhosis, hemolytic anemia, pernicious anemia, sickle cell anemia

—Transferrin

¡Normal male 215-365 mg/dl, female 250-380 mg/dl

¡Largest quantity of iron-binding proteins

—Ferritin

¡Normal male 12-300 ng/ml, female 10-150ng/ml

¡Good indicator of available iron stores in the body (iron storage protein)

¡Decreased – iron deficiency anemia, severe protein deficiency, hemodialysis

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—LACTATE

—Venous normal 5-20 mg/dl

—Arterial normal 3-7 mg/dl

—Lactic acid formed instead of CO2 and H20 when oxygen to muscles diminished and anaerobic metabolism of glucose occurs

—Indicator of tissue hypoxia

—Increased – shock, tissue ischemia, CO poisoning, severe liver disease, genetic errors of metabolism, DM

—LIPID PROFILE

—Cholesterol

¡Normal <200 mg/dl

—Triglycerides

¡Normal male 40-160 mg/dl, female 35-135mg/dl

¡Form of fat transported by VLDL and LDLs

—LDL

¡Normal 60-180 g/dl

¡Bad cholesterol

¡Cholesterol carried by LDLs are deposited into lining of blood vessels

—HDL

¡Normal male >45mg/dl, female >55mg/dl

¡Good carriers of cholesterol

¡Produced in liver and remove cholesterol from tissues and transport to liver for excretion

—

—LFT

—ALT (alanine aminotransferase)

¡Normal 4-36 units/L

¡Mainly found in liver (also kidney, heart, muscles)

¡Released into blood with liver damage

¡10x normal with acute hepatitis

¡Increased – hepatitis, cirrhosis, hepatic tumor, hepatoxic drugs, severe burns, trauma to striated muscle, myositis, pancreatitis, MI, mononucleosis, shock

—ALP (alkaline phophatase)

¡Normal 30-120 units/L

¡Increased with bile duct blockage

¡Found in liver, bone, kidney, intestine, placenta (highest in bone and liver)

¡Increased – cirrhosis, biliary obstruction, liver tumor, healing fracture, metastatic tumor to bone, hyperparathyroidism, Paget disease, RA, sarcoidosis, osteomalacia, Rickets

¡Decreased – hypothyroidism, malnutrition, pernicious anemia, hypophophatemia, scurvy, celiac disease

—AST (aspartate aminotransferase)

¡Normal 0-35 units/L

¡Mostly found in liver and heart

¡Increased – hepatitis, cirrhosis, drug induced liver injury, hepatic metastasis, hepatic surgery, skeletal muscle trauma, severe burns, heat stroke, recent convulsions, heart muscle diseases, acute pancreatitis, acute hemolytic anemia

¡Decreased – acute renal disease, beriberi, dka, pregnancy, chronic renal dialysis

—Albumin

¡Noraml 3.5-5g/dl

¡Evaluate nutritional status

¡Protein that is formed within liver – makes up 60% of total protein

¡Decreased – malnutrition, pregnancy, liver disease

—Total Protein

¡Normal 6.4-8.3g/dl

—GGT (gamma-glutamyl transferase)

¡Normal 45 and older 8-38units/L, female younger than 45 5-27 units/L

¡Main source is liver

¡Participates in transfer of amino acids and peptides across cellular membrane

¡Used to test liver cell dysfunction

¡Most sensitive in detecting biliary obstruction, cholangitis, cholecystitis

¡Does not increase in bone diseases

¡Can detect chronic alcohol ingestion, elevated in 75% who chronically drink

¡Increased – hepatitis, cirrhosis, hepatic necrosis, hepatoxic drugs, jaundice, cholestasis, MI, alcohol, pancreatitis, cancer of pancreas, mononucleosis, CMV, Reye’s syndrome

—LDH, Bilirubin, PT

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LYME TITERS

—IgM and IgG antibodies

—IgM peak during 3rd-6th week after disease onset then gradually decline

—IgG low during first several weeks, then maximal levels 4-6 months later

—ELISA and Western Blot should also be used

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Mono Titers

—EBV titer

—< 1:10 = nondiagnostic

—1:10 – 1:60 = infection at some undetermined time

—1:320 or greater = active infection

—Heterophil agglutination slide test (Monospot test)

¡Appears 5 days, disappears in 2 weeks – acute/convalescent infection

—VCA-IgM – appears 7 days, disappears 3 months, acute/convalescent infection

—VCA-IgG – appears in 7 days, exists for life, acute/convalescent/old infection

—EBNA-IgG – appears in 3 weeks, exists for life, old infection

—EA-D – appears in 7 days, disappears in 2 weeks, acute/convalescent infection

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—THYROID FUNCTION TESTS

—TSH

¡Normal 2-10 uU/mL

¡Released by pituitary by TRH. Low levels of T4 and T3 cause stimulation of TRH and TSH

¡Increased – primary hypothyroidism, thyroiditis, thyroid agenesis, congenital cretinism

¡Decreased – secondary hypothyroidism, hyperthyroidism, pituitary hypofunction

—T4 (thyroxine)

¡Total – normal male 4-12 mcg/dl, female 5-12 mcg/dl, >60 5-11mg/dl

÷Makes up nearly all of what we call thyroid hormone

÷Increased – Grave’s disease, toxic thyroid adenoma, acute thyroiditis, pregnancy, hepatitis, etc

÷Decreased – cretinism, myxedema, pituitary insufficiency, iodine insufficiency, cushing’s syndrome, cirrhosis

—T3 (triiodothyronine)

¡Normal 20-50 y.o. 70-205 ng/dl, >50 y.o. 40-180 ng/dl

¡Less stable than T4, 7-10% thyroid hormone is T3

¡70% bound to TBG

¡Increased – Grave’s disease, toxic thyroid adenoma, acute thyroiditis, pregnancy

¡Decreased – hypothyroidism, myxedema, pituitary insufficiency, protein malnutrition, iodine insufficiency, liver disease, cirrhosis, Cushing’s syndromes

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URIC ACID

—Blood normal male 4.0-8.5 mg/dl, female 2.7-7.3 mg/dl

—Urine normal 250-750 mg/24 hr

—Product of purine catabolism

—Excreted by kidney

—Elevated – gout, increased ingestion of purines, metastatic cancer, MM, leukemia, hemolysis, rhabdomyolysis, chronic renal disease, acidosis, hypothyroidism, toxemia of pregnancy, hyperlipoproteinemia, alcoholism

—Decreased – Wilson’s disease, Fanconi’s syndrome, Lead poisoning,

—UA/URINE CULTURE

—Normal findings

¡Appearance – clear

¡Color – amber yellow

÷Dark red (bleeding from kidney), bright red (bleeding from lower urinary tract), dark yellow (urobilinogen or bilirubin), green (pseudomonas), red (beets), brown (rhubarb), drugs can change it color

¡Odor – aromatic

÷Acetone (DKA), foul odor (UTI), fecal odor (enterobladder fistula)

¡pH – 4.6-8.0

÷Increased (bacteria, UTI, diet high in citrus foods)

¡Protein – none or up to 8mg/dl

÷Increased (nephrotic syndrome), renal disease, preeclampsia, DM

¡Specific gravity – 1.005-1.030

÷Increased – dehydration, SIADH, fever, diarrhea, vomiting

÷Decreased – overhydration, renal failure, diabetes insipidus

¡Leukocyte esterase – negative

÷WBC in urine - UTI

¡Nitrites – negative

÷Bacteria produce enzyme that reduces urinary nitrates to nitrites

¡Ketones – negative

÷DM, starvation, fasting, dehydration

¡Crystals – negative

¡Casts – none

¡Glucose – negative

÷DM

¡WBC – 0-4

¡WBC casts – negative

¡RBC cells <2

¡RBC casts – none

÷UTI, Pyelonephritis, ATN, renal stones

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VITAMIN D

—25-hydroxyvitamin D (major hormone found in blood and inactive precursor) & 1,25-dihydroxyvitamin D (active hormone)

—25-hydroxyvitamin D measured to assess and monitor vitamin D because of longer half life and higher concentration

—25 – hydroxyvitamin D – ordered when calcium low or symptoms of vitamin D deficiency (rickets, osteomalacia)

—1, 25 dihydoxyvitamin D – calcium high or patient has disease that might produce excess amounts of vitamin D

Information obtained from: 

Mosby's Diagnostic and Laboratory Test Reference

Lab Tests Online

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