Answering your questions: water during glucose test, Retortamonas intestinalis, occult blood developers, and amylase and lipase. (Tips from the Clinical Experts).
Water during glucose tolerance test glucose tolerance test
A test for evaluating the body's capability to metabolize glucose and based upon the ability of the liver to absorb and store excess glucose as glycogen.
Q: What is the current thinking about allowing a patient who is undergoing a three- or four-hour glucose tolerance test to have sips of water or ice chips? We used to allow the patient to have sips of water after the first-hour blood specimen was drawn. Can the patient have small sips of water at any point during the tolerance test after the 100 grams of glucose is taken?
A: Your question begs a larger one that challenges the usefulness of a glucose tolerance test (GTT GTT,
n See test, glucose tolerance.
GTT Glucose tolerance test, see there ) in the first place. In 1997, the criteria for the diagnosis of diabetes mellitus was revised to be based on a fasting (eight hour) glucose of >126mg/dL on at least two occasions. Formal GTT are no longer generally recommended. The criteria adopted by the World Health Organization and the American Diabetes Association The American Diabetes Association, or the ADA, is an American health organization providing diabetes research, information and advocacy. Founded in 1940, the American Diabetes Association conducts programs in all 50 states and the District of Columbia, reaching hundreds of as proposed by the National Diabetes Data Group suggest a diagnosis of diabetes mellitus be based on a two-hour post-loading dose (75 gram) blood glucose level blood glucose level,
n level of glu-cose in the bloodstream, normally about 70 to 115 mg/dL after fasting overnight. Higher levels may indicate diseases such as diabetes mellitus. of 200 mg/dL or more. (1) However, performing an oral GTT or extending the testing of a loading-dose level beyond two hours is of decreasing diagnostic value. Likewise, the collection and testing of urine specimens concurrently with diabetic testing is out of favor. Although urine glucose levels can be of some value in diagnosing renal glycosuria, testing urine is of little value in diagnosing diabetes mellitus.
Regardless, ingesting water during a glucose tolerance test is not likely to affect the results to any significant degree, and little evidence exists that it should be restricted. Even though drinking large volumes will undoubtedly hasten the hod/s metabolism of the loading dose and its excretion through the urinary tract, it is not likely to affect a diagnosis.
Dennis J. Ernst MT(ASCP ASCP American Society of Clinical Pathologists. )
Center for Phlebotomy Phlebotomy Definition
Phlebotomy is the act of drawing or removing blood from the circulatory system through a cut (incision) or puncture in order to obtain a sample for analysis and diagnosis. Education Inc. Ramsey. IN
(1.) Henry J., ed. Clinical diagnosis and management by laboratory methods. Philadelphia, PA:WB Saunders Co.; 2001.
Q: What is the clinical significance of recovering Retortarnonas intestinalis from urine sediment? How does it differ from Trichomonas and other parasites?
A: R. intestinalis is rarely seen in urine sediment and is generally not clinically significant because, of the six genera of flagellates flagellates (flaj´lāts),
n.pl one of four phyla of parasitic protozoa, also called
Mastigophora. that parasitize par·a·sit·ize
To live on or in a host as a parasite.
to live on or within a host as a parasite. the human intestinal or urogenital urogenital /uro·gen·i·tal/ (-jen´i-tal) genitourinary.
u·ro·gen·i·tal or u·ri·no·gen·i·tal
Genitourinary. tracts, only Giardia lamblia, Dientamoeba fragilis and Trichomonas vaginalis are considered pathogens. T. vaginalis infects the urogenital tract of males and females, while the other two species reside in the intestinal tract. The other intestinal flagellates, Chilomastix mesnili, Enteromonas bominis, Trichomonas bominis (now Pentatrichomonas bominis) and R. intestinalis are all nonpathogenic commensals. With the exception of D. fragilis and Trichomonas spp., they have both trophozoite trophozoite /tropho·zo·ite/ (-zo´it) the active, motile feeding stage of a sporozoan parasite.
n. and cyst stages. The intestinal flagellates are acquired through fecal-oral transmission while T. vaginalis is transmitted through sexual contact.
T. vaginalis is recovered from vaginal and urethral discharges, prostatic secretions and urine sediment, and is seen more often in urine sediment than the other protozoan protozoan (prō'təzō`ən), informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms that live as single cells or in simple flagellates. The recovery of R. intestinalis, T. bominis or other flagellates from urine sediment usually suggest that the specimen was contaminated by fecal material and warrants careful collection of another urine specimen.
The initial differentiation of R. intestinalis from other trophozoites recovered from urine sediment is based on size and motility motility /mo·til·i·ty/ (mo-til´ite) the ability to move spontaneously.mo´tile
Motility is spontaneous movement. . R. intestinalis, Trichomonas spp., and E. bominis exhibit a jerky motility. The trophozoites of R. intestinalis and E. bominis are pear-shaped or oval and small, measuring 4pm to 10 pm long by 3 pm to 6 pm wide. T vagina/is and T. bominis trophozoites, on the other hand, range in size from 7pm to 23 pm long by 5 pm to 15 pm wide, with T. bominis being slightly smaller. R. intestinalis also has a prominent cytostome, which extends half the length of the body.
David Sewell, PhD. ABMM ABMM American Board of Medical Microbiology
ABMM American Board of Medical Management
ABMM Anti-Ballistic Missile Missile
ABMM American Board of Medical Malpractice
Director of Microbiology
Veterans Affairs Medical Center Portland, OR
Occult blood developers
Q: I have a question regarding substituting occult blood card developers. If the control area of one brand of card reacts properly with the developing solution of a different brand, wouldn't that indicate that the combination of card/developer is acceptable?
A: It is not a good idea to mix reagents from different manufacturers in a test, even when they are similar (but proprietary). Although they might give acceptable control results, controls are usually set to give strong reactions, and the system could fail at a lower analyte concentration.
There is another reason why you should not do this. CLIA CLIA Clinical Laboratory Improvement Amendments of 1988 Congressional legislation that promulgated quality assurance practices in clinical labs, and required them to measure performance at each step of the testing process from the beginning to the end-point of a says that you must follow the manufacturer's instructions when performing a test, or you must have experimental data showing acceptable performance characteristics for the "home-brew" test. That is a hard job to do. It's not a good idea to be out of compliance with CLIA.
Daniel M. Baer, MD Professor Emeritus
Department of Pathology Oregon Health and Science University Portland, OR
Both amylase amylase (ăm`əlās'), enzyme having physiological, commercial, and historical significance, also called diastase. It is found in both plants and animals. Amylase was purified (1835) from malt by Anselme Payen and Jean Persoz. and lipase lipase (lī`pās), any enzyme capable of degrading lipid molecules. The bulk of dietary lipids are a class called triacylglycerols and are attacked by lipases to yield simple fatty acids and glycerol, molecules which can permeate the membranes ?
Q: We have a Beckman CX9 ALX and are trying to decide between running lipase or pancreatic amylase. Is there a significant clinical difference between the tests? We are a 70-bed hospital. If we run lipases, that means we have to stop testing on the CX9 to clean the cuvettes and run the lipase since we run HDL (Hardware Description Language) A language used to describe the functions of an electronic circuit for documentation, simulation or logic synthesis (or all three). Although many proprietary HDLs have been developed, Verilog and VHDL are the major standards. , cholesterol and triglyceride. I want to give the doctors the best test available to help them make the right treatment choice. At present, we are sending lipases to our reference lab, and the turnaround time is between two to three hours, which delays the treatment for our ER patients.
Acute pancreatitis increased ten-fold between 1960 and 1980, and it continues to be a significant cause of death. Roughly one in 10 patients with pancreatitis die during their hospitalization. Between 60% to 80% of the cases are due to alcoholism or a gallstone gallstone: see gall bladder.
Mass of crystallized substances that forms in the gallbladder. The most common type occurs when the liver secretes bile with too much cholesterol to stay in solution. obstructing the bile duct distal to the pancreatic duct. (1)
Amylase, lipase and other measurable digestive enzymes produced by pancreatic acini acini Plural of acinus, eg, milk-producing glands of breast are released into the circulation instead of the digestive tract when there is pancreatic tissue injury due to pancreatic ductal obstruction or other causes of pancreatic inflammation. The clinical usefulness of the measurement of any of these enzymes is related to the ease/cost with which the test(s) can be done and the likelihood that abnormal levels will be detected when the patient presents for diagnosis.
Pancreatic amylase can be measured quite simply now, since methods of inhibiting parotid parotid /pa·rot·id/ (pah-rot´id) near the ear.
1. Situated near the ear.
2. Of or relating to a parotid gland.
A parotid gland. (salivary) amylase with wheat germ or, more recently, monoclonal antibody to parotid amylase have been developed. Both pancreatic amylase and lipase are measured in the typical automated chemistry analyzers by functional assays employing specific substrates. The lipase reaction is sensitive to lipolytic lipolytic,
adj/n the ability to break up fat. or esterase esterase /es·ter·ase/ (es´ter-as) any enzyme which catalyzes the hydrolysis of an ester into its alcohol and acid.
Any of various enzymes that catalyze the hydrolysis of an ester. reagents in other assays, so, in an automated system, it requires scrupulous attention to preanalytical factors, such as reaction chamber carryover of reagents from tests such as triglycerides or cholesterol. (2)
Various authors report somewhat differing timetables for the peak levels and duration of abnormality of pancreatic amylase and lipase. (1,3) More current reviews tell us that the amylase will peak at 12 hours to 72 hours and will fall to normal within a week. Lipase, on the other hand, peaks in about 24 hours after onset of pain, and will remain elevated for eight to 14 days.
In a Tennessee study of 306 ER patients with acute abdominal pain, the 208 nonpancreatic cases had lower maximum enzyme levels than the 48 with acute pancreatitis. The maximum amylase level was 71 times the upper reference limit (URL URL
in full Uniform Resource Locator
Address of a resource on the Internet. The resource can be any type of file stored on a server, such as a Web page, a text file, a graphics file, or an application program. ), whereas the maximum lipase value was 435 times the URL. (4) Another study, comparing a mass concentration assay of lipase to amylase, showed that the median increase in peak pancreatic amylase was about 14 times the upper reference limit (URL), while lipase was about 37 times the URL. (5) Since patients with significant acute pancreatitis usually present to the physician or ER within a week of onset of symptoms, it appears that either test would serve to assist the physician in the diagnosis, and doing both would be redundant. Lipase has the advantage of having the greatest likelihood of being abnormal -- both in amplitude or duration after onset of symptoms.
Physicians are well aware that the enzyme levels may be normal in an acute attack of pancreatitis, so other assessments, both clinical and imaging, are a part of the work-up of acute abdominal pain. Ultrasound and computed tomography are fairly sensitive to demonstrate gallstone obstruction at the Ampulla of Vater Ampulla of Vater
The widened portion of the duct through which the bile and pancreatic juices enter the intestine. Ampulla is a Latin word for a bottle with a narrow neck that opens into a wide body.
Mentioned in: Jaundice or soft tissue changes indicative of edema, necrosis or microcalcifications of the pancreas. They would likely be done in all such cases, not just those in which the enzyme levels were elevated. The laboratory may sometimes document hyperproduction of amylase with increased clearance leading to a "normal serum amylase" by performing the "Amylase/Creatinine Clearance Ratio." Immunochemical assays have been developed to measure the various protein enzymes released by pancreatitis. One of the most promising of these is a urine dipstick dipstick /dip·stick/ (dip´stik) a strip of cellulose chemically impregnated to render it sensitive to protein, glucose, or other substances in the urine. assay (Actim Pancreatitis) which has been designed to measure trypsinogen-2 at thresholds of detection of 50 ng/mL (screening) and 2,000 ng/mL (confirmatory high-specif icity assay). (6)
In conclusion, I would suggest that your situation justifies your present course of action with regard to the costcomplexity vs. benefit analysis. You have a reference laboratory that can support, in a respectable time frame, the occasional need for a lipase assay to help confirm a diagnosis. If you want "to give the doctors the best test available," the literature leans slightly toward lipase.
Louis Buettner, MD
Dynacare--Alabama Reference Laboratories/LabSouth Tuscaloosa, AL
(1.) MunozA & Katerndahl DA. Diagnosis and Management of Acute Pancreatitis. Am Fam Physician. 2000;62:164-74.
(2.) Beckman-Coulter Bulletins 9157EE and 9157FF. Beckman Coulter, Inc., Brea, CA.
(3.) Leclerc P & Forest JC. Variation is amylase seenzymes and lipase daring acute pancreatitis, and in other disorders causing hyperamylasemia. C/in Chum. 1983;29:1020-3.
(4.) Chase CW et al. Serum Amylase and Lipase is the Evaluation of Acute Ahdominal Pain. Am Surg. 1996;62:1028.
(5.) Van Ingen HE & Sanders GT. Clinical evaluation of a pancreatic lipase mass concentration assay. Clin Chum. 1992;38:2310-3.
(6.) Kemppainen EA et al. Rapid Measurement of Urinary Trypsinogen-2 as a Screening Test for Acute Pancreatitis. NEJM NEJM New England Journal of Medicine . 1997;336:1788-93.
MLO's Tips from the Clinical Experts department provides practical, up-to-date solutions to readers' technical and clinical issues from a panel of experts in various fields. Readers may send questions to Dan Baer by fax, (503) 636-7932; or e-mail, Baer.d@portland.VA.gov.
Daniel M. Beer is professor emeritus of laboratory medicine at Oregon Health and Science University n Portland, OR, and a member of MLO's editorial advisory board.