Interpretation Of LAB Data

Lab data interpretation Specialized laboratory tests, which are used to monitor specific disease states or specific drug therapies. Generally, laboratory tests should be ordered only if the results of the test will affect decisions about the care of the patient. Serum, urine, and other bodily fluids can be analyzed routinely; however, the economic cost and impact on the quality of life related to obtaining these data must always be balanced by benefit to patient-specific outcomes

Factors Affecting the Test Result From the Time the Test Is Ordered Until It Arrives at the Laboratory Incorrect test ordered Sample incorrectly labeled Improper preparation for test Collection incomplete or improper Improper handling or storage Technical Result incorrectly read, computer keying error Sex Age Pregnancy

Blood cells Complete blood count Complete blood picture

Platelets (thrombocytes) Platelets are formed in the bone marrow. A marked reduction in platelet number (thrombocytopenia) may reflect either a depressed synthesis in the marrow or destruction of formed platelets. Platelets are normally present in the circulation for 8–12 days.

Platelets (thrombocytes) An increased platelet count (thrombocytosis) occurs in malignancy, inflammatory disease and in response to blood loss.

Platelets (thrombocytes) This is useful information when evaluating a possible drug-induced thrombocytopenia, since recovery should be fairly swift when the offending agent is withdrawn A small fall in the platelet count may be seen in pregnancy and following viral infections. Severe thrombocytopenia may result in spontaneous bleeding.

Erythrocyte sedimentation rate Male: 0–20 mm/hour Female: 0–30 mm/hour The ESR is a measure of the settling rate of red cells in a sample of anticoagulated blood, over a period of 1 h, in a cylindrical tube. The ESR is strongly correlated with the ability of red cells to aggregate into orderly stacks.

Erythrocyte sedimentation rate In disease, the most common cause of a high ESR is an increased protein level in the blood, such as the increase in acute-phase proteins seen in inflammatory disease.

Erythrocyte sedimentation rate The test is principally used to monitor inflammatory disease. The ESR may be raised in the active phase of rheumatoid arthritis, inflammatory bowel disease, malignant disease and infection. The ESR is non-specific and, therefore, of little diagnostic value, but serial tests can be helpful in following the progress of disease, and its response to treatment.

C-reactive protein (CRP) hs-CRP 0–2.0 mg/L This non-specific acute phase response occurs in response to tissue damage, infection, inflammation and malignancy. Production of CRP is rapidly and sensitively upregulated, in hepatocytes.

C-reactive protein (CRP) CRP values are not diagnostic, however, but can only be interpreted in knowledge of all other clinical and pathological results. In most diseases, the circulating value of CRP reflects ongoing inflammation or tissue damage more accurately than ESR.

C-reactive protein (CRP) More sensitive measure of CRP; hs-CRP <1.0 mg/L low risk for cardiovascular disease; 1.0–3.0 mg/L average risk; >3.0 mg/L high risk for cardiovascular disease.

Renal function tests 1.Blood Urea Nitrogen BUN : 8–20 mg/Dl Acute or chronic renal failure is the most common cause of an elevated BUN. Although the BUN is an excellent screening test for renal dysfunction, it does not sufficiently quantify the extent of renal disease. In addition, several non renal factors such as unusually high protein intake and conditions that increase protein catabolism (or upper GI bleeding) can increase the BUN concentration.

Renal function tests 2.Creatinine Creatinine0.6–1.2 mg/dL Its rate of formation for a given individual is remarkably constant and is determined primarily by an individual’s muscle mass. Therefore the SCr concentration is slightly higher in muscular subjects, but unlike the BUN, it is less directly affected by exogenous factors or liver impairment.

Renal function tests Once creatinine is released from muscle into plasma, it is excreted renally almost exclusively by glomerular filtration. A decrease in the glomerular filtration rate (GFR) results in an increase in the SCr concentration. Thus, careful interpretation of the SCr concentration is used widely in the clinical evaluation of patients with suspected renal disease

Liver function tests Serum albumin levels and prothrombin time (PT) indicate hepatic protein synthesis; bilirubin is a marker of overall liver function. Transaminase levels indicate hepatocellular injury and death, while alkaline phosphatase levels estimate the amount of impedance of bile flow.

AST 0–35 units/L

ALT 0–35 units/L

ALP ALP =30–120 units/L

GGT GGT =0–70 units/L

Total Bilirubin Bilirubin—total 0.1–1 mg/dL

Pancreatic enzyme 1.Amylase Amylase=35–120 units/L Pancreatic enzyme; ↑ in pancreatitis or duct obstruction. 2. Lipase Lipase =0–160 units/L ↑ in acute pancreatitis, elevated for longer period than amylase

PSA PSA 0–4 ng/mL ↑ in benign prostatic hypertrophy (BPH) and also in prostate cancer. PSA levels of 4–10 ng/mL should be worked up. Risk of prostate cancer increased if free PSA/total PSA <0.25

Thyroid function test TSH=0.4–5 units/mL ↑ TSH in primary hypothyroidism requires exogenous thyroid supplementation.

Lipid profiles Cholesterol Cholesterol =<200 mg/dL

Lipid profiles 2. LDL LDL= 70–160 mg/dL

Lipid profiles 3. HDL HDL 40=mg/dL

Lipid profiles 4. Triglycerides TG:=<150 mg/dL ↑ by alcohol, saturated fats, drugs (propranolol, diuretics, oral contraceptives). Obtain fasting level.

Lipid profiles 4. Triglycerides TG:=<150 mg/dL ↑ by alcohol, saturated fats, drugs (propranolol, diuretics, oral contraceptives). Obtain fasting level.

Electrolyte panel and Glycemic panel

Cardiac markers

Proteins

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