Lab news-3/02

MDS is in the process of converting to liquid or spatula then after a conventional smear has based collection for Gynecological Cytology.
been prepared. It is important that the attached The production of a monolayer slide in the lab- collection instructions are followed. In particu- oratory results in a more consistent preparation, lar, clockwise rotation of the device five (5) enhancement in slide quality and reduction in times will ensure that an optimal endo-cervical the number of slides reported as unsatisfactory or “limited by” when compared to conventional Please note that we will be able to process only Pap Smears. We have chosen the AutoCyte® sys- samples submitted in the Tripath fixative pro- tem of Tripath Imaging to prepare monolayers.
vided by MDS. Although we anticipate some Collection in your office is simplified because improvement in turn-around-time a significant the collection device is submitted to MDS in shortage of Cytotechnologists will persist into fixative along with all the cells obtained. You no the foreseeable future. It is essential that when longer need to prepare and fix the slide. A bet- expedited interpretation is required for clinical ter and more complete sample is available to the laboratory because the new technique results in many more cells being collected with the brush require treatment unless they are immunocom- promised, when infections tend to be pro- longed. Note that reliable curative treatment for this infection is currently not available. As clinicians continue to care for increasingnumbers of immunocompromised patients and Patients infected with Entamoeba histolytica should receive treatment regardless of sympto- management of infections due to intestinal par- matology. Patients with invasive infection (ie asites continues to be a challenge. In this issue colitis, amoebic abscess) should always receive of LabNews, treatment regimens for common an intraluminal agent such as iodoquinol after pathogenic parasites are summarized in Table 1.
treatment with metronidazole.3 Please note that Factors prompting referral to specialists for fur- the laboratory is not able to discriminate ther treatment advice may include: clinical and between pathogenic E. histolytica and nonpatho- immune status of the patient, pathogenicity of genic E. dispar by microscopic techniques.
the organism, and first-line therapy “failures”. Introduction . . . . . . . . . . . . . . . . 1 Physicians are encouraged to order specific E.
histolytica serology testing in order to delineate In some instances, the decision to offer specific Parasitic Infections . . . . . . . . . 1,2 treatment may depend upon the clinical status of the patient. For example, only symptomatic patients infected with Dientamoeba fragilis 1. Can J Infect Dis, 1998; 9(2): 69-70.
should receive treatment.1 The same principle 2. Lee et al., CID 2000; 30: 401-402.
3. The Medical Letter, January 1998; 40(1017): 1-12.
applies to patients with giardiasis, althoughfood handlers, the immunocompromised and those infected as a result of an outbreak should receive treatment, regardless of symptoms.2 Patients with cryptosporidiosis do not usually Table 1: Treatment Regimen for Common Pathogenic Parasites Ascaris lumbricoides
Cyclospora
Dientamoeba
fragilis
Entamoeba histolytica
asymptomatic infection
symptomatic infection Metronidazole
Enterobius
11 mg/kg once (max. 1 gram); 11 mg/kg once (max. 1 gram); vermicularis
Giardia lamblia
Trichuris trichura
Footnotes:
* These drugs must be obtained through the Special Access Programme by calling 613-941-2108.
** Contraindicated in pregnancy and children under the age of 8.
By: A. Sarabia, MD, FRCPC, Director, Medical Microbiology 2
A review of the MDS reference range was complet-ed prior to implementation on December 13, 2001.
Folic acid is an essential nutrient in the prevention of The revised PTH reference interval is 1.5-6.5 neural tube defects (NTD). In November 1998, pmol/L. Due to the important physiological Canada implemented a program to ensure folic acid relationship between PTH and calcium, it is supplementation of all pasta, flour and grain products.
always important to interpret PTH results in Following implementation of this program, a ret- conjunction with circulating levels of serum total rospective review of population data collected in Ontario by MDS indicates that significantlyfewer individuals are at risk for folate deficiency.
Defined as a decrease in RBC folate concentra-tion (< 215 nM), the number of folate deficient cases noted prior to fortification was 57 of 3200patients reviewed (1.8%). Post-implementation, Utilization of the 4 hour or 5 hour glucose toler- this number decreased to 17 of 4102 (0.4%) of ance test (GTT) for diagnosis of hypoglycemia is requests reviewed.1 In addition, the mean con- no longer recommended. The preferred test for centration (95 % CI) of RBC folate increased initial investigation of suspected postprandial from 680 (669-692 nM) to 852 (841-862 nM) hypoglycemia is measurement of a single blood glucose, collected 2-5 hours after a standardized Considering this data and that presented by mixed meal or carbohydrate load. The most QMP-LS, measurement of this analyte will be accurate assessment includes repeated blood glu- cose measurements at times when the patient is ed of having any of the following conditions may still benefit from folate testing: malnutrition, For the investigation of postprandial hypoglycemia, alcoholism, anemia, gastrointestinal malabsorption.
order a 2-5 hour post meal blood glucose level. Thetime of meal ingestion must be provided to the labo- ratory to permit correct interpretation of the results.
1. Ray JG, Vermeulen MJ, Boss SC and Cole DEC. Clin.
Biochem. 2000; 33(5): 337-343.
A post meal glucose level of less than 2.5 mmol/L, 2. QMP-LS Endocrinology Committee Comments,
Folate patterns of practice survey
on more than one occasion, is suggestive of reac- R-9908-PP, Endocrinology 2000; 3(2.2): 49-56.
tive hypoglycemia. To rule out true fasting hypo-glycemia, individuals should, subsequently, beevaluated using a supervised 72 hour fastingtest. For further assistance, please consult the MDS Clinical Biochemist at extension 2363. C-PeptideDue to a manufacturers change in the calibrationof the C-peptide kit, physicians may observe asignificant decrease of up to 40% in reported serum C-peptide concentrations. A review and validation of the manufacturers stated referencerange is in progress. Implementation of the Deep insertion of a collection device into the cer- reformulated kit is scheduled for March 4, 2002. vical canal is inadvisable in pregnancy. In orderto obtain a sample in pregnant women, the Cervex® broom provided by MDS can be used in a man- The PTH assay utilized by MDS has been refor- ner similar to the spatula which was included in mulated to include the use of a new pair of mono- the kits for conventional smears. The central bris- clonal and polyclonal antibodies. This change in tles of the Cervex® brush should not be inserted format has resulted in an assay of increased sensitiv- deep into the canal but by firm pressure and rota- ity and specificity to the intact PTH molecule.
tion in a clockwise direction, the device may be Note that reported concentrations of serum PTH used to sample the external os and ectocervix. A may be up to 28% lower than previous values. vaginal pool sample may also be obtained.
3
(continued from page 3 - Lab Notes) This type of analysis may also be useful in the investigation of patients with isoen- CK activity. A relative index greater than Creatine Kinase, CK, exists in five molecu- zyme secreting tumours, heterophilic anti- bodies or persistent asymptomatic elevated infarction, (AMI), while, indices between variants. The three CK isoenzymes are CK- total CK activities. Analysis is not auto- 2-4% are “borderline high” and warrant mated and is labour intensive, hence pro- derived from brain, myocardial and skeletal isoenzymes analysis precludes its use as a muscle, respectively, while CK variants are routine test for investigating acute myocar- dial infarction. CK isoenzyme analysis or appropriate medical response is to direct fractionation does not provide added value the patient to a near-by hospital with emer- in patients suspected of muscle disorders.
gency services so that immediate care can other isoenzymes or fractions appear as a monitored with quantitation of total CK.
If further assistance is required, please con- healthy older women, often associated with normal or slightly elevated total CK but are (U/L) is used in the investigation of sus- 1. Moss DW et al. Enzymes: In Tietz Textbook of
Clinical Chemistry, 2nd ed., Burtis C. A. &
Ashwood E. R. eds., W. B. Saunders Co. 1994,
797 – 809.
assays are preferred due to improved preci- 2. Lee KN, Csako G, Bernhardt P and Elin RJ.
tionation is used to investigate patients sion, rapid analysis capabilities, enhanced Clin Chem 1994; 40: 1278 – 1283.
with unexplained total CK results or pres- sensitivity and specificity. Results of CK- 3. Thompson RJ, Jackson AP and Langlois N. Clin
Chem 1986; 32: 476 – 481.
MB assays are usually expressed in absolute patients receiving animal derived therapies.
concentration (ug/L) and as the “relative 4
Published byMDS Laboratory Services a division of MDS Inc.
Your comments and suggestions are welcomed. Please contact us at: Medical Support Department100 International Blvd.,Toronto, OntarioM9W 6J6 F O U R S I M P L E S T E P S
disconnect the entire brush from requisition form with patient O N E C L E A R R E S U L T
In clinical trial studies, cervical samples were taken and first smeared onto slides. Residual cells from the conventional smear
were used in the AutoCyte PREP process. In each case, the same patient sample, with very different results.
The conventional smear, although diagnosed as “within normal limits” can be considered an unsatisfactory specimen, and the patient “limited” with the cells hidden by excessive is called back in for another sample.
diagnosed as “within normal limits.” C a n c e r D e t e c t i o n a n d P r e v e n t i o n 100 International Blvd., Toronto, Ontario M9W 6J6

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