Clinical Laboratory Final Exam PDF

Determine the Uric Acid Concentration in Serum and Urine Clinical Significance Level of uric acid efected by exerscise and diet that contain purine. Uric acid normaly excretion through urine,increased uric acid in blood is generally accompanied by increased excretion in urine.uric acid leve...

Determine the Uric Acid Concentration in Serum and Urine Clinical Significance Level of uric acid efected by exerscise and diet that contain purine. Uric acid normaly excretion through urine,increased uric acid in blood is generally accompanied by increased excretion in urine.uric acid levels increased in several disease such as renal failure, leukemia, multiple myeloma, lymphoma, glycogenesis, chronic hemolytic anemia, pernicious anemia lymphosarcoma and particularly increased up to 6.5–12 mg/dl is observed gout, where uric acid is deposited as crystals in jointes. -Estimation of Total Calcium in Serum and Urine Calcium is the most abundant mineral cation in the body which contains 1– 1.5 kg of total body weight in the adults. About 50% of total plasma calcium exists in ionized form which is functionally most active. Calcium binds to negatively charged sites on proteins which is pH dependent. Alkaline conditions promote calcium binding and decrease free calcium, whereas acidic conditions decrease calcium binding and increase free calcium levels. Ionized and citrate-bound calcium is diffusible from blood to the tissues, while protein bound is no diffusible. In the laboratory, all three fractions of calcium are measured together. Clinical Significance: Calcium levels are increased in hyperparathyroidism (determination of ionized serum calcium is more useful for the diagnosis of hyperparathyroidism), Hypocalcemia is more serious and life-threatening condition than hypercalcemia.. In rickets, the product of serum calcium and phosphorus decreases usually below 30 mg/dl. An increase in alkaline phosphatase activity is a characteristic feature of rickets. Estimation of Inorganic Phosphorus in Serum and Urine: Phosphorus has two forms organic present in the soft tissues incorporated into macromolecules and as inorganic form. Phosphorous is also present in some proteins, lipids, and nucleic acid and in some coenzymes. The phosphorus of the blood is of four types: 1. Inorganic phosphorus – the phosphates of alkaline and alkali earth metals, present as H2PO4 and HPO4-2. The ratio of H2PO 4 and HPO4-2 is pH dependent. as the inorganic phosphorus present in serum which is measured 2. Organic or ester phosphorus – including glycerophosphates, nucleotide phosphate, hexose phosphate, etc. Estimate the Amount of Total Cholesterol in Serum Cholesterol is a precursor of :  vitamin D  steroid hormones  bile acids Estimate Total and Direct Bilirubin in Serum Theory In reticuloendothelial cells the porphyrin part of destroied heme is converted to Biliverdin and then reduced to bilirubin called unconjugated bilirubin (insoluble in water) which is then transported to the liver in association with albumin. In the microsomes of hepatocytes bilirubin conjugated by the action of glucuronyl transferase to produce bilirubin monoglucuronide and diglucuronide (conjugated bilirubin). Conjugated bilirubin is water soluble and it exerted through bile. In the intestine bilirubin is reduced by bacterial action and is also deconjugated, mainly in the colon to “urobilinogens.” Urobilinogen is recycled through the body and a part of it is excreted through the urine. Fig.(Bilirubin metabolism and elimination)  Clinical Significance: In hemolytic jaundice, the unconjugated bilirubin is increased due to increased destruction of red blood cells. In pernicious and chronic hemolytic anemia, 3 mg/dl but may also reach up to 10 mg/dl. 1. In hepatic jaundice, conjugated bilirubin decreases along with decreased excretion of bilirubin. The concentration of total bilirubin increases greatly in blood without any significant change in their ratio. 2. In posthepatic jaundice (obstructive jaundice), the concentration of conjugated bilirubin is increased (up to 20 mg/dl) compared to unconjugated bilirubin. Increased serum bilirubin indicates extrahepatic biliary tract obstruction and hemolytic diseases. 3. Total serum bilirubin amount >40 mg/dl indicates hepatocellular obstruction and not extrahepatic obstruction. 4. Urine bilirubin and urobilinogen are important in differential diagnosis of jaundice. Bilirubinuria is present in obstructive jaundice but absent in hemolytic jaundice. Determine Alanine and Aspartate Transaminase Activity in Serum (AST&ALT) Theory They are enzymes present in a specific tissue which catalyze reversible transfer of α-amino group from amino acid to α-keto acid. They are present in almost all cells, but higher amounts occur mainly in the liver, brain, heart, and kidney. Two clinically important transaminases are: 1. Glutamine oxaloacetate transaminase (SGOT), also called aspartate aminotransferase (AST), 2. Glutamine pyruvate transaminase (SGPT) also called alanine aminotransferase (ALT). High concentration in the liver and kidney, and trace amounts are present in the skin, pancreas, spleen, lungs, and cardiac and skeletal muscle.  Both AST and ALT enzymes are not excreted in urine unless a kidney lesion is present. The measurement of these enzymes is a useful diagnosis indicator of liver functions. Estimate the Activity of Alkaline Phosphatase in Serum Theory The ALP of normal serum in adults is mainly derived from the liver and bone and small amount from intestinal component. During childhood the majority of alkaline phosphatase is of skeletal origin. During pregnancy, ALP is also contributed from the placenta. ALP is activated by magnesium ions. The activity in serum is due to isoenzymes from various organs, but the major contribution occurs from the liver. Clinical Significance 1. Increase in serum ALP activity is usually associated with hepatobiliary obstruction (all forms of jaundice except hemolytic jaundice), due to defect in excretion of ALP through bile, the elevation of ALP is more marked in extrahepatic obstruction (gallstone, cancer of the head of the pancreas, etc.) than intrahepatic obstruction. 2. Increased ALP levels are also observed in increased osteoblastic activity, rickets, hyperthyroidism, and bone disorders. 3. A small increase in ALP activity may also occur in congestive heart failure, intra-abdominal bacterial infections, and intestinal diseases. Also be observed in multiple myeloma and impaired calcium absorption. 4. Decrease in serum ALP is observed during severe anemia, celiac disease, zinc and magnesium deficiency, scurvy, cretinism, hypothyroidism, and hypophosphatemia.