Vivas

Are there any other methods to determine serum creatinine? 1) The LX20 modular chemistry side uses the Jaffe rate method (kinetic alkaline picrate) to determine the concentration of creatinine in serum, plasma, or urine. A precise volume of sample is introduced into a reaction cup containing an alkaline picrate solution. Absorbance readings are taken at both 520 nm and 560 nm. Creatinine from the sample combines with the reagent to produce a red color complex. The observed rate measurement at 25.6 seconds after sample introduction has been shown to be a direct measure of the concentration of the creatinine in the sample. 2) Enzymatic method employing creatinine iminohydrolase, NADPH employed as cofactor. The Jaffe method is affected by numerous interferents that can cause creatinine results by this method to be falsely increased or decreased. Examples of interferents include glucose, protein, bilirubin, hemolysis, and lipemia.[1] Modifications to the original Jaffe method and the advent of kinetic enzymatic methods, with and without rate blanking, have reduced the error in creatinine measurement caused by the presence of various interferents. EXPECTED VALUES: Serum 0.5 - 1.7 mg/dL SENSITIVITY: This procedure has a sensitivity of 0.025 mg/dL per 0.001 absorbance unit. Creatinine measurements are useful in the diagnosis and treatment of renal diseases. URIC ACID: Serum Uric Acid is the end product of purine metabolism in the body tissues and is cleared through the kidneys by glomerular filtration. Increased uric acid levels may result from leukemia, polycythemia, ingestion of foods high in nucleoproteins (e.g., liver and kidney) or impaired renal function. Gout results from the deposit of uric acid in body joints. Uric acid has been assayed by the reduction of phosphotungstic acid and by the direct measurement at 293 nm before and after uricase treatment. The products of the uricase reaction have been used also as a basis for uric acid determinations. The phosphotungstic acid method lacks specificity and the uricase procedures are cumbersome and insensitive. Other Methods: The URIC ACID (TPTZ) PROCEDURE employs the ferric- reduction. This method offers a sensitive and rapid uric acid determination in which interference is minimized. One mole of uric acid reduces four moles of ferric ions to the ferrous form. 2, 4, 6 - tripyridyl-s-triazine (TPTZ) reacts with the ferrous ions to form a blue colored complex which absorbs strongly at 590 nm. Drugs that can increase uric acid measurements include alcohol, ascorbic acid, aspirin, caffeine, cisplatin, diazoxide, diuretics, epinephrine, ethambutol, levodopa, methyldopa, nicotinic acid, phenothiazines, and theophylline.

Drugs that can decrease uric acid measurements include allopurinol, high-dose aspirin, azathioprine, clofibrate, corticosteroids, estrogens, glucose infusion, guaifenesin, mannitol, probenecid, and warfarin. PhosPhor: Test is performed to evaluate the blood level of phosphorus, particularly when the person has a disorder known to cause abnormal phosphorus levels. Most of the body's phosphorus is combined with calcium in the bones, but about 15% exists -- as phosphate (PO4) ions -- in the blood and other soft tissues and body fluids. Dietary phosphorus is efficiently absorbed, so a low PO4 level caused by dietary deficiency is unlikely in those on a normal diet unless the person has a malabsorption syndrome (inadequate absorption of nutrients in the intestinal tract). PO4 levels are controlled by PTH, 1,25-dihydroxy vitamin D. The 1,25-dihydroxy vitamin D increases absorption of calcium and phosphate in the intestines. • • •

PTH: Increases calcium and PO4 release from bone Decreases loss of calcium and increases loss of PO4 in the urine Increases conversion of 25-hydroxy vitamin D to 1,25-dihydroxy vitamin D in the kidneys

Antacids can bind PO4 and decrease absorption. Nonpharmacological factors that can affect PO4 measurements include: enemas containing sodium phosphate, excess vitamin D supplements, and intravenous glucose administration (because PO4 enters cells along with glucose). Drugs that can increase PO4 measurements include: laxatives containing Na2HPO4 (sodium phosphate), methicillin, and excess vitamin D or 1,25-dihydroxy vitamin D. The medical laboratory test for serum iron measures the amount of circulating iron that is bound to transferrin.Clinicians order this laboratory test when they are concerned about iron deficiency, which can cause anemia and other problems.65% of the iron in the body is bound up in hemoglobin molecules in red blood cells. About 4% is bound up in myoglobin molecules. Around 30% of the iron in the body is stored as ferritin or hemosiderin in the spleen, the bone marrow and the liver. Small amounts of iron can be found in other molecules in cells throughout the body. None of this iron is directly accessible by testing the serum.However, some iron is circulating in the serum. Transferrin is a molecule produced by the liver that binds one or two iron(III) ions; transferrin is essential if stored iron is to be moved and used.Most of the time, about 30% of the available sites on the transferrin molecule are filled. The test for serum iron uses blood drawn from veins to measure the iron molecules that are bound to transferrin, and circulating in the blood.The extent to which sites on transferrin molecules are filled by iron ions can be another helpful clinical indicator, known as percent transferrin saturation. Another lab test saturates the sample to measure the total amount of transferrin; this test is called total iron-binding capacity (TIBC). These three tests are generally done at the same time, and taken together are an important part of the diagnostic process for anemia, iron deficiency and iron deficiency anemia.

Usual values

Serum Iron (SI): Men: 65 to 176 µg/dL Women: 50 to 170 µg/dL Newborns: 100 to 250 µg/dL Children: 50 to 120 µg/dL TIBC: 240-450 µg/dL Transferrin saturation: 20-50% o o o o

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µg/dL = micrograms per deciliter. Laboratories often use different units and "normal" may vary by population and the lab techniques used; look at the individual laboratory reference values to interpret a specific test (for instance, your own). Copper An essential mineral that is a component of several important enzymes in the body and is essential to good health. Copper is found in all body tissues. Copper deficiency leads to a variety of abnormalities, including anemia, skeletal defects, degeneration of the nervous system, reproductive failure, pronounced cardiovascular lesions, elevated blood cholesterol, impaired immunity and defects in the pigmentation and structure of hair. Copper is involved in iron incorporation into hemoglobin. It is also involved with vitamin C in the formation of collagen and the proper functioning in central nervous system. More than a dozen enzymes have been found to contain copper. The best studied are superoxide dismutase (SOD), cytochrome C oxidase, catalase, dopamine hydroxylase, uricase, tryptophan dioxygenase, lecithinase and other monoamine and diamine oxidases. Serum The cell-free fluid of the bloodstream. It appears in a test tube after the blood clots and is often used in expressions relating to the levels of certain compounds in the blood stream.

BUN levels can be too low as well as too high. Abnormally low BUN Low levels of BUN may indicate overhydration, malnutrition, celiac disease [a disease characterized by the inability ot tolerate foods containing wheat protein (gluten)], liver damage or disease, or use of corticosteroids. Low BUN may also occur in early pregnancy. Abnormally high BUN High levels of BUN may indicate kidney disease or failure; blockage of the urinary tract by a kidney stone or tumor; a heart attack or congestive heart failure;

dehydration; fever; shock; or bleeding in the digestive tract. High BUN levels can sometimes occur during late pregnancy or result from eating large amounts of proteinrich foods. A BUN level higher than 100 mg/dL points to severe kidney damage.

A bilirubin test is a diagnostic blood test performed to measure levels of bile pigment in an individual's blood serum and to help evaluate liver function. The bilirubin test is an important part of routine newborn (neonatal) diagnostic screening tests. The level of bilirubin in a newborn's blood serum is measured to determine if the circulating level of bilirubin is normal or abnormal. Bilirubin is a yellow-orange bile pigment produced during the breakdown of hemoglobin, the iron-bearing and oxygen-carrying protein in red blood cells. All individuals produce bilirubin daily as part of the normal turnover of red cells. A higher than normal (elevated) bilirubin test can reflect accelerated red blood cell destruction or may indicate that bilirubin is not being excreted as it should be, suggesting that liver function problems or other abnormalities may be present. Neonatal bilirubin screening often reveals an elevated bilirubin (hyperbilirubinemia). The bilirubin test will determine if hyperbilirubinemia is present and, along with other diagnostic tests, help determine if the condition is relatively normal (benign) or possibly related to liver function problems or other conditions. Usually all newborns (neonates) delivered in the hospital will have total serum bilirubin (TSB) measured in the clinical laboratory on one or more blood samples as requested by attending pediatricians. To obtain a blood sample for TSB, a phlebotomist takes blood from the infant's tissue (usually the heel) rather than from a vein, as the veins of newborns are extremely small and easily damaged. After sterilizing the surface of the site with alcohol and/or an antibacterial solution such as betadine, a heel puncture is made and blood from the puncture is drawn into a tiny capillary tube about 2 inches (5 cm) long that is stoppered at each end when full. This tube is spun down in a special centrifuge in the laboratory to separate serum, the liquid part of blood, from red cells. In the TSB test, spectrophotometry is used to identify and quantify the amount of bilirubin in a specific amount of serum by measuring the amount of ultraviolet light absorbed by bilirubin pigment in the sample. The test method requires only minutes and a very small amount of blood serum to produce accurate results, measuring the results in milligrams per desiliter (mg/dL). The amount of total bilirubin in circulating blood can be calculated from the results of a single bilirubin test. Results are compared to known normal values to determine if the individual has normal or abnormal levels. All newborn infants begin to destroy fetal red blood cells (RBCs) in their first few days of life, replacing them with new red blood cells. The rapid destruction of red blood cells and subsequent release of fetal hemoglobin into the bloodstream results in the production of bilirubin. As a waste product, bilirubin is filtered out of blood (cleared) by the liver and excreted in bile, eliminated normally in stool produced by the large intestine. However, immediately after birth, more bilirubin is produced than the infant's immature liver can handle, and the excess remains circulating in the blood. This situation results in jaundice in over 60 percent of newborns, usually due to the

presence of fetal hemoglobin released into the blood during the normal destruction of fetal red blood cells. Even healthy infants may appear to have a yellow stain in their skin (physiological jaundice or icterus) and the whites of the eyes (sclerae) in the first week after birth. This may first be noticed by pediatric nurses as they care for the infant. Visual evaluation of jaundice is not considered a reliable way, however, to determine its cause or the risk of continued rising of bilirubin and possible complications. Performing bilirubin tests is the first step in making sure that normal degrees of jaundice do not become more severe and that liver dysfunction or other causative conditions, if present, are identified and treated early. Besides normal red cell destruction after birth, neonatal hyperbilirubinemia may also be caused by the following: • • • • • • • •

low birth weight feeding or nutrition problems glucose 6-phospho-dehydrogenase (G6PD) deficiency insufficient intestinal bacteria incompatibility of major blood groups (ABO) between mother and baby blood type (Rh) incompatibility (rare due to treatment of Rh negative mothers) genetic abnormalities linked to a history of jaundice among siblings liver dysfunction

From 8 to 9 percent of newborns develop severe hyperbilirubinemia. Severe hyperbilirubinemia is of great concern to pediatricians because it may lead to bilirubinrelated brain damage (kernicterus). Persistent elevated levels of bilirubin in the body can place infants at risk of neurotoxicity or bilirubin-induced neurologic dysfunction (BIND). The risk of liver dysfunction has been shown to be higher in infants who were born before term (less than 37 weeks' gestation) or who have other abnormalities in addition to an elevated total serum bilirubin. Some pediatricians order bilirubin tests at defined times within 24 to 48 hours after birth to monitor the rate of increase of bilirubin and to help determine associated risks on an individual basis. Infants with a low rate of rise in bilirubin (less than 17mg/dL per hour) are considered lower risk and are likely to be discharged without further testing or treatment. Those who show visual jaundice at birth or within several hours after birth and whose rate of bilirubin rises more rapidly are considered at higher risk for severe hyperbilirubinemia and associated kernicterus, especially if the bilirubin level is still rising at time of discharge. Some newborns are placed under special lamps (phototherapy) to help correct the jaundice caused by elevated bilirubin levels and to bring down the bilirubin level. Supervision of breastfeeding and supplemental nutritional support may be needed to help infants who are not getting their nutritional needs met. Exchange transfusions may be given for high-risk infants, especially those with blood group (ABO) or type (Rh positive infants born to Rh negative mothers) incompatibilities. Additional tests may be required to evaluate G6PD deficiency, genetic abnormalities, or liver function. After discharge from the hospital, about 25 percent of otherwise healthy infants who are still showing signs of jaundice may continue to be tested for bilirubin levels. An elevated bilirubin usually goes down on its own if the hyperbilirubinemia is benign; if

liver dysfunction or other abnormalities exist, bilirubin levels may remain elevated or continue to rise, indicating that further diagnostic testing, clinical evaluation, and treatment are needed. Precautions

Performance of the bilirubin test itself is a precaution against the serious consequences that can occur when bilirubin levels continue to rise in jaundiced infants. Visual jaundice present at birth may predict rapid rises in bilirubin and risk of liver dysfunction or other abnormalities. Preparation

No preparation is needed before performing bilirubin tests on infants' blood samples. Proper identification and careful handling of the infant are important when a blood sample is being obtained for testing. A site, usually on the infant's heel, is chosen by the phlebotomist who draws the infant's blood sample. The area is prepared by wrapping the baby's foot in a warm cloth for a few minutes to bring blood to the surface and allow it to flow more easily. The heel is then wiped with alcohol and/or an antibacterial solution such as betadine to sterilize the surface. The heel is then punctured with a lancet, avoiding the center of the heel, in order to prevent inflammation of the bone. The blood sample is drawn in tiny capillary tubes, properly labeled, and taken to the laboratory for testing. In rare instances, a phlebotomist is not able to draw sufficient blood from a heel puncture, and a physician may draw venous blood from a femoral vein in the groin area, which is larger than veins in an infant's arms. Aftercare

The site from which blood is withdrawn must be kept clean after the procedure and must be checked regularly for bleeding. A small adhesive patch may be used to protect the site. Risks The performance of bilirubin tests carries no significant risk. Drawing blood for the test may involve light bleeding or bruising at the site of puncture, or blood may accumulate under the puncture site (hematoma), requiring that a new location be found for subsequent tests. Not performing bilirubin tests, however, may have significant risks for some infants. Infants with rising bilirubin levels are at risk of neurotoxicity and developing kernicterus, making the monitoring of bilirubin in the first week of life critical for these infants. Normal Results At birth, a newborn's TBS is normally 1 or 2 mg/dL, peaking at 6 mg/dL in three or four days. In 10 days to two weeks, a healthy infant's TBS is expected to be less than 0.3 mg/dL.

During the first seven days of the infant's life, TBS results are rated for risk of bilirubin toxicity or bilirubinrelated brain damage within percentile ranges representing degrees of hyperbilirubinemia. TBS values less than 20 mg/dL are lowerrisk percentile ranges below the 95th percentile, with an incidence of one in nine infants. TBS values greater than 20 mg/dL are in the 98th percentile, with an incidence of one in 50 infants; greater than 25 mg/dL are in the 99.9 percentile, with an incidence of one in 700 infants; and TBS values greater than 30 ng/dL are at the highest level of risk at 99.99 percentile, indicating almost certain neurotoxicity. One in 10,000 infants are in the 99.99 percentile. Parental Concerns Parents will usually be informed by the pediatrician about any risks associated with an elevated bilirubin, such as liver dysfunction or possible kernicterus. Parents concerned about these risks can be made aware that bilirubin levels usually return to normal in most infants (more than 60%) and the related jaundice goes away gradually. Testing after the baby is discharged is sometimes necessary (in 25% of infants) and is a preventive measure rather than a cause for concern. Repeat testing is necessary to monitor bilirubin levels. Parents should be aware that, although the baby's heel may be bruised, elevated bilirubin levels can cause serious complications, and testing is critical to help prevent them. BCG: is a dye of the triphenylmethane family (triarylmethane dyes), which is used as a pH indicator and as a tracking dye for DNA agarose gel electrophoresis. It can be used in its free acid form (light brown solid), or as a sodium salt (dark green solid). Albumin A type of globular protein that is characterized by its solubility in water and in 50% saturated aqueous ammonium sulfate. Albumins are present in mammalian tissues, bacteria, molds, and plants, and in some foods. Serum albumin, which contains 584 amino acid residues, is the most abundant protein in human serum, and it performs two very important physiological functions. It is responsible for about 80% of the total osmotic regulation in blood, and it transports fatty acids from adipose tissue to muscle. When excessive amounts of albumin are found in the urine upon clinical examination, some form of kidney disease is usually indicated. Another important albumin, ovalbumin, is found in egg white. This protein is about two-thirds the size of serum albumin, and it contains sugar residues in addition to amino acid residues Hyperalbuminemia Overproduction of albumin is not known to occur. •

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Physiologic: Hyperalbuminemia is a relative change seen with dehydration. Globulins will also increase in this situation, resulting in hyperproteinemia with no change in A:G ratio. Laboratory error: Albumin values can be artifactually elevated in severely lipemic or hemolyzed samples, but this is analyzer- and method-dependent. Albumin is also higher in heparinized plasma than serum (due to nonspecificity of bromcresol green which also binds to globulins, including

fibrinogen), however newer procedures have been developed to minimize this phenomenon. Hypoalbuminemia • •

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Physiologic: Excessive fluid administration (overdilution). Decreased production 1) Decreased production can occur if there are insufficient amino acids available for hepatic production of albumin. This occurs in cases of chronic severe malnutrition due toiency), or starvation. 2) The liver is the main site of albumin production. Chronic hepatic disease will result in hypoalbuminemia when there is a > 80% reduction in functional mass. 3) Acute phase reactions stimulate downregulation of albumin production. An acute phase reactant response is initiated in response to trauma, inflammation, neoplasia, etc and involves release of cytokines (IL-1, IL-6, TNF) from macrophages. These cytokines act on regulatory elements in hepatocyte genes, resulting in upregulation of transcription of acute phase reactant proteins (fibrinogen, serum amyloid A protein, ceruloplasmin, haptoglobin) and downregulation of transcription of other proteins, including albumin and transferrin (so-called "negative acute phase reactants"). Increased degradation of albumin may also play a role in the hypoalbuminemia in this reaction. In this case, the A:G is decreased due to the combination of low albumin and high globulins. Note that an acute phase reactant response is associated with an increase in alpha2 globulins on serum electrophoresis. Increased loss of albumin This occurs with the following: 1) Protein-losing glomerulopathy: This can result in nephrotic syndrome which is characterized by proteinuria, hypoalbuminemia, hypercholestorelemia and edema. In these conditions, albumin is lost, but globulin levels are maintained, resulting in a low A:G. 2) Severe hemorrhage: Both albumin and globulins are lost, resulting in a normal A:G. 3) Protein-losing enteropathies. In these conditions, both albumin and globulins are lost concurrently, thereby maintaining a normal A:G. There are exceptions to this, e.g. Basenjis with immunoproliferative bowel disease have hyperglobulinemia. 4) Severe exudative dermatopathies. This is also associated with concommitant albumin and globulin loss (A:G tends to remain normal). Sequestration: Hypoalbuminemia can be due to sequestration of albumin within body cavities, e.g. peritonitis. Catabolism: Increased albumin catabolism occurs with a negative energy or protein balance, e.g. chronic infections, neoplasia, trauma.