فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

15 апреля 2024 16:13

STRAND-DISPLACEMEN AMPLIFICATION
Strand-displacement amplification (SDA) is an isothermal template amplification technique that can be used to detect trace amounts of DNA or RNA of a particular sequence. SDA as it was first described was a conceptually straightforward amplification process with some technical limitations (Walker et al., 1992a; Walker et al., 1992b). Since its initial description, however, it has evolved into a highly versatile tool that is technically simple to perform but conceptually complex. In its current iteration, SDA occurs in two discrete phases: target generation and exponential target amplification (Little et al., 1999). In the target generation phase, a dsDNA target is denatured and hybridized to two different primer pairs, designated as bumper and amplification primers (Fig. 69.7). The amplification primers include the single-stranded restriction endonuclease enzyme sequence for BsoB1 located at the 5′ end of the target binding sequence. The bumper primers are shorter and anneal to the target DNA just upstream of the region to be amplified. In the presence of BsoB1, an exonuclease-free DNA polymerase, and a dNTP mixture consisting of dUTP, dATP, dGTP, and thiolated dCTP (Cs), simultaneous extension products of both the bumper and amplification primers are generated.
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 21:39

Confirm ABO and Rh types on donor red cell units as required. • Confirmation testing for ABO group required on all units (serum testing not required). • Confirmation of Rh type required only on those units labeled as Rh negative (weak D testing is not required).
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 21:25

103) اینترلوکین 6 در موارد التهابی تولید می شود که منجر به کاهش موقتی آهن و افزایش چندین برابری فریتین (به علت اینکه نوع پروتئین التهالی است) می شود. و ربطی به MCV بالا ندارد.

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 21:04

101 )
The separated plasma ideally should be platelet free (<10 K) before freezing because frozen plasma that is rich in platelets upon thawing will cause disruption of platelets releasing platelet factor 4, which binds to heparin and may give false low anti-FXa activity, or phospholipids released from platelet membranes bind to lupus anticoagulant and may give false-negative results.
..
Thrombin Time (TT)
Thrombin time (TT) is usually not a commonly ordered test because of its limited utility in laboratory assessment of most bleeding disorders. In the TT test, bovine thrombin (3–5 U/mL) is added to the patient’s plasma and the clotting time recorded. The upper limit of the normal range should be adjusted close to 25 sec to make TT more sensitive to detect dysfibrinogenemia. The most frequent cause of prolonged TT is heparin followed by hypofibrinogenemia and then dysfibrinogenemia. Direct thrombin inhibitors (oral and parenteral) significantly prolong TT.
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 19:18

پاسخ سوال 99 )
TABLE 35.1
Use of CD13 and CD16 simultaneously to demonstrate neutrophilic maturation
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 19:04

Cytochemically, these cells contain acid phosphatase, which is resistant to inhibition by tartrate-resistant acid phosphatase; this is in contrast to the isoenzymes of acid phosphatase present in other hemic cells (Yam, 1971). Immunophenotype is mature B cell (CD19, CD20, CD22, CD79a, DBA.44, FMC-7, and surface membrane immunoglobulin [SMIg]) with expression of hairy cell–associated markers CD103, CD25, CD11c, CD123, annexin A1 (ANXA1), and (dim) cyclin D1 (Falini, 2004). Cells are negative for CD5, CD10, and CD23. Immunoglobulin heavy-and light-chain genes are rearranged, with somatic mutation of V gene regions. HCL shows consistent BRAF V600E mutation (Tiacci et al., 2011; Waterfall et al., 2014).
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:49

پاسخ سوال 96)
In some cases, erythroid cells may show strong cytoplasmic PAS
positivity (Fig. 34.37). This is granular in early erythroid precursors and diffuse in later stages. Erythroid precursors are PAS negative in normal individuals and in most diseases, including nutritional megaloblastic anemia. They are sometimes positive, however, in iron deficiency anemia, thalassemia, and MDS with ring sideroblasts. Ring sideroblasts may be seen in erythroleukemia, and myeloblasts usually stain with SBB, MPO, and CAE. A nonspecific esterase-positive monocytic component may also be present. Neoplastic erythroid precursors are sometimes positive for ANA and ANB.
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:42

95) در عفونت های کرمی معمولا اول درمان را همراه پیگیری نتایج درمان طی چندماه بررسی می کنند . اینکه در سایر گزینه ها الف و ب و ج برویم سراغ کشیدن مغز استخوان، یا بررسی نئوپلاسم و .... منطقی نیست .

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:36

سوال 94 )
Laboratory Investigation of Hemoglobinopathies and
Thalassemias
گزینه الف )
Current practices include automated complete blood count (CBC); ferritin
or free erythrocyte protoporphyrin to rule out iron deficiency; and high-performance liquid chromatography (HPLC) or capillary electrophoresis for HbA2 and HbF measurement and detection of Hb variants; followed by alkaline and acid electrophoresis when a variant is found and additional studies (Sickledex, molecular studies), as necessary.
گزینه ب)
Hemoglobin Electrophoresis and Isoelectric Focusing.
Hb molecules in an alkaline solution have a net negative charge and move toward the anode in an electrophoretic system. A practical method for routine Hb electrophoresis is cellulose acetate at alkaline pH. It is rapid and reproducible and separates the major Hb variants S, D, G, C, and E from HbA (Figs. 33.17 and 33.18). Quantification of the major bands is easily accomplished. Those with an electrophoretic mobility greater than that of HbA at pH 8.6 are known as the “fast Hbs”; these include, in order of increasing mobility, Hbs K, J, Bart’s, N, I, and H. Hbs A2, C, E, and O Arab at the slow end are unresolved from each other, as are S, D, G, and Lepore. Citrate agar electrophoresis at an acidic pH provides ready separation of Hbs that migrate together on cellulose acetate: S from D and G, and C from E and O (Fig. 33.19). Isoelectric focusing separates Hbs based on their isoelectric point along a pH gradient, with high resolution (Fig. 33.20) (Basset, 1982).
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:30

Transient Erythroblastopenia of Childhood
Transient erythroblastopenia of childhood (TEC) occurs in previously
healthy children, usually younger than 8 years of age, with most affected children between 1 and 3 years of age. It is characterized by a moderate to severe normocytic anemia that develops gradually, severe reticulocytopenia, transient neutropenia (20%), and increased platelet counts (60% of patients). Macrocytosis is usually observed during recovery because of the effects of reticulocytes. A history of a viral infection within the previous 3 months is frequently elicited. The bone marrow is generally normocellular and shows virtual absence of erythroid precursors, except for a few early forms. Granulocytic maturation arrest may occur in some neutropenic patients. Patients recover within 1 to 2 months without therapy except in rare occasions in which RBC transfusions may be needed for symptomatic anemia. TEC can occur in siblings simultaneously and in seasonal clusters. Transient neurologic manifestations, such as hemiparesis and seizures, may accompany TEC. In most cases, the pathogenesis involves humoral inhibition of erythropoiesis; cell-mediated immunosuppression was identified in about 25% of cases, but parvovirus has not been proven to be the cause of TEC (Narla, 2019).
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:20

92)
Percent Saturation of TIBC. The ratio of serum iron to TIBC is the percent saturation of the TIBC. Normally, this is 20% to 55%; values below 15% indicate iron-deficient erythropoiesis. A marked diurnal variation in serum iron by as much as 30% normally occurs, with highest values in the morning and lowest values late in the day. Consequently, fasting morning blood specimens are preferred for the diagnosis of iron deficiency. The TIBC remains relatively constant in a normal individual. Pregnancy and oral contraceptives increase TIBC.

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:14

٩١- درخصوص اندازهگیری‌ طول عمر موثر گلبولهای‌ قرمز خون به‌ کمک‌ کروم رادیواکتیو کدام گزینه‌ صحیح‌ است‌؟

الف‌) پایش‌ اندازه گیری‌ بقاء گلبولهای‌ قرمز با تزریق‌ مستقیم‌ 51Cr به‌ خون محیطی‌ از طریق‌ ورید سفالیک‌ انجام می‌شود.

ب) 51Cr به‌ مارپیچ‌ بتا در زنجیره آلفا وصل‌ شده و قسمت‌ اعظم‌ آن تا تخریب‌ کامل‌ گلبولهای‌ قرمز باقی‌ می‌ماند.

ج) پایش‌ رادیواکتیویته‌ 51Cr تا از بین‌ رفتن‌ ٥٠ درصد اکتیویته‌ زمان صفر ادامه‌ می‌یابد.

د) میران نرمال نیمه‌ عمر گلبولهای‌ قرمز با استفاده ار روش 51Cr حدود ٦٠ روز است‌.

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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

27 марта 2024 20:13

Under conditions of acute stress, AVP and copeptin are secreted in stoichiometrically equivalent amounts, but copeptin is more suitable for laboratory analysis because of its greater stability. Following demonstration that copeptin is elevated following MI (Khan et al., 2007), studies suggested that copeptin measurement could improve early rule-out of NSTEMI compared with cTn alone (Reichlin et al., 2009; Ricci et al., 2016).
....
BOX 19.2:
Recommendations of a Joint Committee of the American Heart Association and the Centers for Disease Control and Prevention on CRP Testing to Assess CHD Risk.
.....
علت غلط بودن گزینه الف ) صفحه 275 داریم :
OTHER HEART FAILURE BIOMARKERS
Given the limited diagnostic power of BNP testing, there has been interest in developing additional markers and possibly pursuing a multimarker strategy for diagnosis and management of HF Two markers of current interest are Gal-3 (galectin-3) and ST-2 (suppressor of tumorigenicity 2) (Karayannis et al., 2013). Gal-3, first named “Mac-2” when it was discovered in mice (Ho & Springer, 1982), was later characterized as one of a family of lectins with an affinity for β-galactosides. Having a role in cell adhesion and other cellular processes, it is present in diverse tissues and elevated in many diseases
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

27 марта 2024 19:56

٨٩- یک‌ بیمار با دیابت‌ شدید در حالت‌ بیهوشی‌ به‌ اورژانس‌ بیمارستان ارجاع گردید و انـدازهگیـری‌ HbA1c انجـام شـد. نتایج‌ نشان داد که‌ میزان HbA1c= 5% می‌باشد. اگرچه‌ همراهان بیمار تصدیق‌ کردند که‌ وی‌ مبتلا به‌ دیابت‌ می‌باشد. آزمایش‌ مجددا تکرار شد ولی‌ نتایج‌ همچنان حاکی‌ از میزان HbA1c= 5% بود. همه‌ مـوارد زیـر بـا احتمـال بـالایی‌ می‌تواند دلیل‌ یافته‌ فوق باشد، بجز:

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

27 марта 2024 19:50

٨٨- بیماری‌ با دفع‌ پتاسـیم‌ ادراری‌ کمتـر از mEq/mg of creatinine 0.01 بـه‌ اورژانـس‌ بیمارسـتان ارجـاع داده شـد. آزمایشات تکمیلی‌ نشان داد که‌ آنیون گپ‌ ادراری‌ وی‌ mmol/24h 20 می‌باشد (آنیون گپ‌ نرمال در ادرار mmol/24h (40 است‌. محتمل‌ترین‌ دلیل‌ یافته‌های‌ فوق کدام است‌؟

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 21:40

سوالات بعدی پاسخ 106 تا 120 #ژنتیک فلوشیپ ورودی 402 است 👇
برای دسترسی به اولین سوالات ازمون روی پین کانال کلیک کنید

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 21:34

Choosing Which AHG Reagent to Use

The DAT is an important diagnostic serologic technique used for the detection of antibody binding to RBC membranes in vivo. Laboratory indications include testing cord cells for HDFN, investigation in HTR, and in AIHA studies. The reason for the testing will indicate the type of reagent that should be used. Polyspecific AHG reagents containing both anti-IgG and anticomplement activity are typically used for initial DAT evaluation. This is especially important when the DAT is being performed to aid in the diagnosis of CAIHA and some forms of drug-induced hemolytic anemia in which complement may be the only evidence of immune-mediated hemolysis. Circulating red cells that have been involved in complement activation will have mostly C3d on their surface as the result of complement regulatory protein degradation of C3b (see Fig. 36.1). Therefore, polyspecific AHG sera used in DATs must contain anti-C3d reactivity and usually contain some anti-C3b reactivity as well. One notable exception to the use of polyspecific AHG for DATs is cord blood. Because only IgG can cross the placenta, the DAT may be performed with an anti-IgG reagent only (see Prenatal and Postnatal Testing section).

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 21:08

پاسخ سوال 102)
TABLE 43.6

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 20:03

Combined Deficiency of Vitamin K–Dependent Clotting Factors Vitamin K–dependent clotting factor deficiency affecting multiple vitamin K–dependent coagulation (II, VII, IX, and X) and anticoagulant (protein S and protein C) factors occurs with vitamin K deficiency and hepatic dysfunction. It also results from heritable dysfunction of hepatic enzyme γ-glutamyl carboxylase (type I) or the vitamin K epoxide reductase enzyme complex (type II) (Brenner et al., 1998; Zhang & Ginsburg, 2004).
Severely affected individuals may present as neonates with fatal hemorrhages,umbilical stump bleeding, or spontaneous intracranial hemorrhage; in infancy or early childhood with hemarthroses, soft-tissue hematomas, or gastrointestinal hemorrhages; or as adults with easy bruising, mucosal bleeding, and bleeding following surgery. Diagnosis is established by the prolongation of both APTT and PT and associated reductions in levels of vitamin K–dependent clotting factors. These patients may respond to vitamin K (oral or parenteral) supplementation with normalization of APTT, PT, and factor levels, as well as the resolution of bleeding symptoms. This makes the establishment of a diagnosis of an inherited abnormality difficult in that other acquired causes of vitamin K deficiency (hemorrhagic disease of the newborn, liver disease, and prolonged use of broad-spectrum antibiotics) or factitious warfarin administration could manifest similarly. For patients who do not respond fully to vitamin K administration, fresh frozen plasma can be used for acute bleeding or surgery. In addition, prothrombin complex concentrates and combination therapy and vitamin K supplementation may constitute alternative treatment options (Napolitano et al., 2010).

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 19:09

Classical Hodgkin Lymphoma
Mixed cellularity, nodular sclerosis, lymphocyte-depleted, and lymphocyte-rich classical subtypes have similar biology, and a common neoplastic cell referred to as the Hodgkin Reed-Sternberg (HRS) cell. They are all referred to as “classical” HL (King et al., 2014; Swerdlow, 2017; Venkataraman et al., 2014). The most common phenotype of HRS cells in classical HL is expression of CD30, CD15, PAX5, MUM1, and fascin with absence of CD45 and T-cell markers. B-cell– associated markers CD20 and/or CD79 are expressed in a minority of cases (<30%) and are usually focal and weak. Occasional cases show strong CD20 expression. B-cell
transcription factors
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:51

٩٧- بیماری‌ ٦٠ ساله‌ با ضعف‌، تب‌، درد شدید ناحیه‌ پهلو و اسپلنومگالی‌ محسوس به‌ بخش‌ مراجعه‌ نمـوده اسـت‌. بررسـی‌ خون محیطی‌ سیتوپنی‌ شدید رده مونوسیتی‌ و گلبول های‌ قرمز را نشان می‌ دهد. بیوپسی‌ مغـز اسـتخوان در بـار اول بوده (اصطلاحاً: تَپ‌ِ او س ش‌ است‌!) و در بیوپسـی‌ دوم نمـایی‌ شـبیه‌ لنفـوم سـلول B بـزرگ (large B cell lymphoma) گزارش می‌ شود. در بررسی‌ سیتوشیمیایی‌ لام مغز استخوان ایزوآنزیم‌ خاصی‌ از اسید فسـفاتاز گـزارش شده است‌. برای‌ تشخیص‌ قطعی‌ و افتراقی‌ این‌ بیماری‌ کدام پانل‌ منطقی‌ تر به‌ نظر می‌رسد؟

الف‌) CD14, CD5, FMC7, CD20, CD19
ب) CD11c, CD25, CD20, CD19, CD117
ج) CD5, CD33, CD34, CD20, CD19
د) CD25, CD103, CD5, CD10, CD19
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:44

٩٦- در تشخیص‌ آزمایشگاهی‌ لوسمی‌های‌ میلوئید حاد کدام گزینه‌ صحیح‌ نمی‌باشد؟

الف‌) میلوبلاست‌های‌ اولیه‌ با استفاده از مارکرهای‌ CD117, CD33 قابل‌ ردیابی‌ هستند.

ب) در AML with t (8;21) بیان CD33 ضعیف‌ بوده و گاهی‌ با بیان CD56 همراه است‌.

ج) برای‌ بررسی‌ inv (16) در AML-M4 علاوه بر کاریوتایپ‌ می‌توان از روشهای‌ FISH و RT-PCR استفاده کرد.

د) با توجه‌ به‌ مثبت‌ بودن رنگ‌ PAS در پیش‌ سازهای‌ نرمـال رده اریتروئیـدی‌ نمـی‌ تـوان از ایـن‌ رنـگ‌ جهـت‌ افتـراق آنمـی‌ مگالوبلاستیک‌ از AML-M6 استفاده کرد.
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:37

٩٥- بیماری‌ ٢٠ ساله‌ با علایم‌ شدید درد شکم‌ و سابقه‌ درمان عفونت‌ کرمی‌ رودهای‌ به‌ بخش‌ مراجعه‌ نموده است‌ در بررسـی‌ آزمایشگاهی‌ وی‌ تمامی‌ پارامترهای‌ خونی‌ نرمال بوده و تنها افزایش‌ خفیف‌ بازوفیل‌ (٣ درصد) دیده مـی‌ شـود. کـدام روند برای‌ ادامه‌ بررسی‌ بیماری‌ را توصیه‌ می‌کنید؟

الف‌) بررسی‌ سریع‌ جهت‌ نئوپلاسم‌های‌ میلوپرولیفراتیو از جمله‌ CML
ب) انجام کومبس‌ مستقیم‌ جهت‌ بررسی‌ آنمی‌های‌ همولیتیک‌ با توجه‌ به‌ افزایش‌ بازوفیل‌ها
ج) انجام بیوپسی‌ مغز استخوان جهت‌ پایش‌ بیماری‌های‌ ذخیره چربی‌
د) اقدام فوری‌ لازم نیست‌ و آزمایش‌ها می‌بایست‌ در چند ماه آینده تکرار شود
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:31

٩٤- در پایش‌ آزمایشگاهی‌ هموگلوبینوپاتی‌ها و تالاسمی‌ها کدام گزینه‌ صحیح‌ است‌؟

الف‌) واریانت‌های‌ تشخیص‌ داده شده با روش HPLC معمولا با یک‌ روش دیگر همانند الکتروفورز تایید می‌شوند.

ب) به‌ هموگلوبین‌ هایی‌ همانند هموگلوبین‌ N و I که‌ در pH:8.6 سریع‌ تر از هموگلوبین‌ A حرکت‌ می‌ کننـد هموگلـوبین‌ هـای‌ سریع‌ گفته‌ می‌شود.

ج) در افراد نرمال با استفاده از روش الوشن‌ اسیدی‌ در pH:3.3 کمتر از ١ درصد گلبول های‌ قرمز حاوی‌ هموگلـوبین‌ F بـوده و F cell نامیده می‌شوند.

د) از روش Gap- PCR به‌ صورت عمده در تشخیص‌ حذفهای‌ بزرگ بتاتالاسمی‌ استفاده می‌شود.

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:21

٩٣- در آپلازی‌ خالص‌ رده اریتروئیدی‌ (PRA) کدام گزینه‌ صحیح‌ است‌؟

الف‌) در فرد دارای‌ آنمی‌ همولیتیک‌ که‌ حملات آپلازی‌ پاروو ویروسی‌ دارد به‌ خاطر کاهش‌ سلول های‌ BFU-E در مغز استخوان، برای‌ رهایی‌ از این‌ وضعیت‌ حداقل‌ ٢ ماه زمان نیاز دارد.
ب) در کودکی‌ که‌ دچار اریتروبلاستوپنی‌ گذرا (TEC) می‌ شود آنمی‌ نرموسیتیک‌ شـدید دیـده شـده و در اکثـر مـوراد پلاکـت‌ افزایش‌ نشان می‌دهد.
ج) در آنمی‌ بلک‌ فان دیاموند (DBA) در اکثر موارد سطح‌ هموگلوبین‌ F نسبت‌ به‌ افراد نرمال ٥ تـا ٢٥ درصـد کـاهش‌ نشـان می‌دهد.
د) اکثریت‌ بیماران مبتلا به‌ آپلازی‌ رده اریتروئید اکتسابی‌ همانند تیموما به‌ درمان به‌ داروهای‌ سرکوبگر سیستم‌ ایمنـی‌ پاسـخ‌ می‌دهند.

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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

13 апреля 2024 18:18

پاسخ سوال 91 :
MEASUREMENTS OF EFFECTIVE SURVIVAL OF
ERYTHROCYTES IN BLOOD
The erythrocyte survival can be determined by removing a sample of blood, labeling the erythrocytes with chromium-51 (51Cr), inactivating the excess 51Cr remaining in the plasma, and reinjecting the labeled erythrocytes into the patient. The 51Cr is bound to the β-chain of the hemoglobin molecule and, for the most part, is not released until the red blood cell is removed from the circulation and the hemoglobin is degraded. Measurements of radioactivity in the red blood cells are made at 2 hours or 24 hours (the zero time, or 100% level) and at 1-to3-day intervals until over 50% of the activity has disappeared. The results are usually expressed as the 51Cr half-survival time. The normal range is 28 to 38 days. (The reason it is not 60 days is that 51Cr is eluted from the hemoglobin at the rate of about 1% per day.) If production of erythrocytes equals destruction (i.e., if a steady state exists), the erythrocyte survival is also a measure of effective production of erythrocytes.

فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

27 марта 2024 20:19

سوالات بعدی پاسخ ۹۱ تا ۱۰۵ #خون_شناسی فلوشیپ ورودی 402 است 👇
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

27 марта 2024 20:01

89)
All HbA1c assays are affected by blood loss, blood transfusions, and conditions that affect the age or survival of red blood cells, such as
hemolysis, pregnancy, and the use of drugs that stimulate erythropoiesis (Little et al., 2019). Shortened red blood cell survival or lower mean age will lower HbA1c levels as a result of reduced exposure to plasma glucose. HbA1c assays vary in reliability in the presence of a variety of other factors. Interference by carbamylated hemoglobin can occur with uremia in some older methods, and salicylates can cause interference by acetylated species. Hemoglobinopathies (HbSS, HbSC, HbCC, HbD trait, HbE trait, elevated fetal hemoglobin HbF) can adversely affect accuracy in certain assays as can iron deficiency and hemodialysis (Tarim et al., 1999; Little et al., 2019). Vitamins C and E can falsely lower levels by inhibiting glycosylation, but vitamin C can also increase levels in some assays. Sample storage effects may occur. Hyperglycemia has been associated with a decrease in erythrocyte survival, suggesting that HbA1c levels in poorly controlled patients may underestimate their mean plasma glucose concentration (for an updated list, see
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

27 марта 2024 19:55

88)
Diarrhea as the cause of metabolic acidosis is first suspected from history, but history is often misleading because the severity of diarrhea cannot be easily determined. The measurement of urine anion gap is useful in determining the severity of diarrhea. The urine anion gap, which is measured as urine (Na+ + K+) − urine Cl−, is reduced or negative when diarrhea is severe. The low urine anion gap in diarrhea is explained by the preferential loss of Na+ + K+ in excess of Cl− because diarrheal fluid contains more Na+ + K+ than Cl−, as some of these cations are balanced by bicarbonate and organic anions. In other types of metabolic acidosis, the urine anion gap is not altered as long as there is no extrarenal loss of electrolytes that are components of the urine anion gap (Oh & Carroll, 2002). Once extrarenal acidosis is excluded, renal acidosis is the only
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فلوشیپ یا دوره تکمیلی علوم آزمایشگاهی

22 февраля 2024 14:07

55.
IN VIVO TEST TECHNIQUES: SKIN TESTS AND END-ORGAN
CHALLENGE TESTS
In discussing the use of laboratory tests in the diagnosis and management of allergic diseases, it is important to mention commonly used in vivo tests, particularly the skin prick test and end-organ challenge tests. In vivo tests are regarded by many allergy specialists in the United States as standards of diagnostic accuracy and reliability. The ability to reproduce a specific allergic reaction by in vivo challenge is considered the most highly predictive technique for demonstrating sensitization and for defining allergic reactivity to aeroallergens, venoms, and drugs. Despite this widely held opinion, the results of skin tests can be highly variable (McCann, 2002). Sources of variability include lack of standardization for the majority of diagnostic skin testing extracts, differences in the potency of allergen extracts available for testing, and differences in the techniques employed by different operators. Skin tests are performed by prick/puncture and intradermal injection methods (Demoly, 1998). The response to intradermal injection of an allergen extract is graded by measuring the diameter of the wheal and Skin tests also are performed by the prick method. Skin prick testing makes use of more concentrated allergen extracts, up to 1000-fold greater concentrations than are used for intradermal testing. A mean wheal diameter of 3 mm is commonly considered the threshold for a positive reaction. The wheal size provides an estimate of the degree of sensitization. A more quantitative estimate of sensitization can be obtained by the technique of endpoint titration. Serial, tenfold dilutions of allergen extract are used, beginning with the most dilute solution (Turkeltaub, 2000). The endpoint is defined as the greatest dilution that produces a 1+ reaction. End-organ challenge tests are useful both in the diagnosis and clinical management of the allergic patient. Adaptations include the bronchial provocation test in the evaluation of asthma; the double-blind, placebo-controlled food elimination and open food challenge test in the diagnosis of food allergy; and the rarely used sting challenge in the diagnosis of anaphylactic sensitivity to insect venom. Use of challenge tests in routine clinicalsituations is limited by the lack of well-standardized allergen extracts of defined potency and by the limited number of allergens that can be tested in an individual on a single occasion. As an example, double-blind food elimination and challenge procedures require periods of abstinence of several days between introduction of suspected foods (Sampson et al., 2012). Although generally regarded as the most reliable test for food allergy, the double-blind, placebo-controlled food challenge test is performed by relatively few practicing allergists.
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