檢驗數據判讀 莊子儀醫師 胸腔內科 內科加護病房主任
Why do you need to check lab? • How do you evaluate a patient? • Interrogation • Physical examination • Blood examination • Image examination • Special examination
Classification of lab work • Hematology test • Blood biochemistry • Serology • Body fluid • Urine and stool • Bacteriology and virology • Histopathology
Hematology test • What kind of patient do you need to check hematology test? • Symptoms and signs of blood loss, inadequate blood production • Symptoms and signs of infection, inflammation and malignancy • Symptoms and signs of coagulopathy • Routine
Complete Blood Count (CBC) • Hemoglobin (Hb) • Hematocrit (Hct) • Red blood cells (RBCs) • Mean cell volume (MCV) • Mean cell hemoglobin conc. (MCHC) • White blood cells (WBCs) • Differential count • Platelet count
CBC • What do you expect if patient has blood loss? • Hb, Ht decrease • Macrocytic, normocytic or microcytic anemia? • MCV, RBC increase or decrease • Normochromic, or hypochromic anemia? • MCH, MCHC normal or decrease • Acute or chronic? • Reticulocyte count
WBC • What do you expect if patient has infection, inflammation or malignancy? • WBC increase or decrease • Leukocytes shift to left • Monocytes increase • Abnormal or immature WBC • Thrombocytopenia
PLT • What do you expect if patient has coagulopathy? • Thrombocytopenia • PT, aPTT increase
Pancytopenia • CBC, WBC, PLT decrease • Severe infection • Malignancy • Drug effect • Liver cirrhosis, uremia etc.
Blood biochemistry • Liver function • Renal function • Cardiac enzymes • Diabetic test
Liver function • Albumin, bilirubin, PT • AST, ALT, ALP, rGT
Albumin • Produced by theliverand contributes approximately 80% of serum colloid osmotic pressure • T1/2 of albumin is about 20 days • Lost directly from the blood because of hemorrhage, burn, or exudates, or it may be lost into the urine or stool because of nephrotic syndrome and chronic diarrhea
Bilirubin • Breakdown product of Hb • Exceeds 0.2-0.4 mg/dL, bilirubin will begin to appear in the urine • Conjugated bilirubin: water soluble, measured as D-bil • Unconjugated bilirubin: water insoluble, bound to serum albumin, measured as T-bil – D-bil
Bilirubin • Increased direct(conjugated): hepatocelluar injury, biliary obstruction/cholestasis (gallstone, tumor, stricture, drug-induced) • Increased indirect(unconjugated): so-called “hemolytic jaundice” caused by any type of the hemolytic anemia, newborn jaundice
Prothrombin time • Direct measurement of activity of clotting factors VII, X, prothrombin (factor II), and fibrinogen • The INR is the PT ratio that would result if WHO’s international reference thromboplastin were used to test the pt’s blood sample
Aspartate Aminotransferase • Abundant in heart and liver tissue and moderately present in skeletal muscle, the kidney, and the pancreas • Evaluate myocardial injury and to diagnose and assess the prognosis of liver disease resulting from hepatocellular injury • Higher than that of ALT in cirrhosis
Alanine Aminotransferase • Relatively more abundant in hepatic tissue, more liver-specific enzyme • ALT>AST in viral hepatitis, AST >ALT in alcohol hepatitis
Alkaline Phosphatase • Different physiochemical properties and originate from different tissues: liver, bone, placenta, intestine • The presence of early bile duct abnormalities can result in ALP before bilirubin are observed.
Alkaline Phosphatase • Drug induced cholestatic jaundice (eg., chlorpromazine or sulfonamides) can ALP. • ALP is an excellent indicator of space-occupying lesions in liver because of disruption of biliary canaliculi within liver.
-Glutamyl Transferase • Major clinical value for hepatobiliary disease. • GT is a sensitive indicator of recent alcohol exposure (GT/ALP>1.4). • More responsive to biliary obstruction (5-50 times of upper limit of normal) • Useful in the diagnosis of obstructive jaundice, intrahepatic cholestasis
Case discussion • 24歲男性病人，主訴疲倦，深棕色尿，身體檢查呈現黃疸，lab data如下： • AST (IU/L): 1543 (5-40) • ALT (IU/L): 2230 (15-40) • T-Bilirubin (mg/dl): 16 (0.2-1.3) • D-Bil. (mg/dl): 11.1 (0.1-0.4)
Renal function • BUN, creatinine, electrolytes • Blood gas, lactic acid • Urine analysis
Blood Urea Nitrogen • End-product of protein metabolism • Azotemia (elevation of BUN) • Dehydration • Blood loss • Steroid • Renal failure • Heart failure
Creatinine • Derived fromcreatine and phosphocreatine, major constituent of muscle • Ccr reflects the glomerular filtration rate (GFR)
Creatinine • BUN:Cr ratio • BUN/Cr >20 in prerenal and postrenal azotemia • BUN/Cr <12 in acute tubular acidosis • BUN/Cr between 12 and 20 in intrinsic renal disease
Urine • Normal are not present (eg., glucose, blood, ketone, and bile pigments) • Appearance: slightly yellow, clear • pH: 5.0~8.0 • Specific gravity : 1.005~1.030 • Occult blood (O.B): not present • Sugar : not present • Protein : not present • Bilirubin/urobilinogen • Nitrite/leukocyte esterase • Microscopic examination: RBC(0-2)HPF, WBC(0-6), cast(0-2), yeast, crystals(0-3), and epithelial cells(0-5)
Blood gas • Step 1 • pH = ? Acidosis / Alkalosis • Step 2 • HCO3- or PCO2 ? Metabolic or Respiratory • Step 3 • Well compensation ? • Mix ?
Blood gas • Metabolic acidosis: PCO2= 1.5x HCO3- +(8 ± 2) • Metabolic alkalosis: HCO3- 1 nmol/L PCO2 0.6~0.7 mmHg • Respiratory acidosis • Acute : PCO2 10 mmHg HCO3- 1 nmol/L • Chronic : PCO2 10 mmHg HCO3- 4 nmol/L • Respiratory alkalosis • Acute : PCO2 10 mmHg HCO3- 2 nmol/L • Chronic : PCO2 10 mmHg HCO3- 5 nmol/L
Case discussion • 22歲男性病人主訴有下肢水腫，五年前有急性腎絲球腎炎病史及輕微的蛋白尿。血壓130/84mmHg，實驗室檢查結果如下: • RBC in urine (0~1) :8~10/HPF • Albumin in urine (neg) : 4+ • 24-hrs urine protein(0~150) : 829 mg/24hr • Serum total protein (6~8) : 7.6 gm/dL • Serum albumin (3.5~5.0) : 2.0 gm/dL • Serum total cholesterol (125~200) :483 mg/dL
CKtotal CK-MB SGOT LDH total LDH-1 Cardiac enzymes
Creatine Kinase • Suspected MI or muscle disease, heart, skeletal muscle, and brain with high levels. • Total CK can be increase by strenuous exercise, IM injections of drugs that are irritating to tissue (eg., diazepam, phenytoin), acute psychotic episodes or myocardial injury.
Creatine Kinase • CK-MB: myocardium,(3-10 U/L) increased in acute MI (begin in 2-12hrs, peak at 12-40 hrs, returns to normal in 24-72 hrs), pericarditis with myocarditis, rhabdomyolysis, crush injury, Duchenne’s muscular dystrophy, polymyositis, malignant hyperthermia, and cardiac surgery. • CK-MB level >25 U/L usually are associated with a MI, the absolute amount may vary depending on the assay technique used.
Troponin-I • The detection of the presence of troponin T and I is more specific and sensitive indicator of myocardial damage. • Troponin within 4hrs of AMI, enabling clinicians to initiate appropriate therapy very quickly following presentation to the ED.
Diabetic test • Glucose AC/PC • HbA1c
Glucose AC/PC • The fasting plasma glucose and 2hrs post-prandial glucose tests commonly are used for evaluating glucose homeostasis. • Diagnosis of DM: • Fasting blood glucose>126 mg/dL • Symptoms of diabetes plus a random plasma glucose 200 mg/dL • Plasma glucose 200 mg/dL at 2hrs following a 75g glucose load
HbA1c • Measurement of HbA1C(normal range 4.6-6.5% ) indicative of glucose control during the preceding 2-3 months.
Normal Values • Abnormal laboratory values are not always of diagnostic significance and normal values sometimes can be interpreted as being abnormal in some disease. • Various factors (eg., age, gender, weight, height, time since last meal, drugs) can affect the range of normal values for a given test. • Each laboratory has its own set of normal value.
Laboratory Error • Spoiled specimen • Specimen taken at wrong time • Incomplete specimen • Faulty reagents • Technical errors • Diagnostic and therapeutic procedures • Diet • Medication