Clinical Chemistry Test Questions – Flashcards

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question

low free PSA fraction or elevated bound PSA fraction

PSAfree:PSAtotal <10%

correlates with?

answer

Prostate cancer

PSA=protease-->minimize the viscosity of the ejaculate

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Prostatic manipulation and instrumentation --> effect

- PSAtotal

- PSAfree

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- minimal

- markedly=> measure before/several weeks after manipulation

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Specimen handling

PSAfree

answer

processed within 2hrs / freeze

-->less stable than bound PSA

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When % PSAfree measurement-->advantage?
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prostate volume < 60cc
question

PSAtotal = 2.5 - 4.0

?test can improve prostate Ca diagnosis

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increased pro-PSA and truncated PSA isoforms1

1pPSA-->anomalous clipping

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Correlation between PSA and tm reccurence
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weak in first 5yrs post treatment

preop--> PSA ~ tumor volume and stage

 

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Nonneoplastic coditions a/w elevated CEA1
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Smoking, peptic ulcer dz,IBD,pancreatitis, hypothyroidism, biliary/bowel obstruction, cirrhosis

1CEA < 10ng/mL

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CEA elevations in malignancies other than colon
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Gastric(well diff, intest. type), breast, lung,pancreas,cervical,urothelial, MTC
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Colorectal Ca and degree of CEA elevation

Affected by?

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Tumor stage, grade, site (L>R), ploidy

obstruction,liver function (metabolism)

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post-treatment surveillance of colorectal Ca
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serial CEA measurements

most sensitive--> liver mets

poorly sensitive--> locoregional recurrence

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Thyroglobulinserum - Cause of

1. Underestimation

2. Overestimation

answer

Anti-thyroglobulin Ab's-;10% (nml Indiv.),;20%Pt w thyroid Ca

2. Macro-thyroglobulin

;

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Pt w PTC/FTC and;anti-thyroglobulin Ab's

Tumor marker?

answer

Serial quantitative [anti-thyroglobulin Ab]serum

increase<--Ag stimulation<-- recurrence

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Marker for mucinous ovarian Ca, Urothelial Ca & RCC
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Tumor-Associated Trypsin Inhibitor (TATI)

also in pancreatic adenoca-->limited specificity (pancreatitis)

gastric ca (60%) --> diffuse, infiltrative,signet ring

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TATI expression and tumor prognosis
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Adverse prognostic factor
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Nonneoplastic cause of TATI elevation
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Renal failure

Pancreatitis--> degree of elevation ~ severity

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CA 125

Major role in monitoring of which Pt

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Non-mucinous epithelial ovarian neoplasm

elevated only ~ 50% --> stage I dz

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elevated CA 125

Nonneoplastic causes

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Pregnancy,fibroids, benign ovarian cysts, pelvic inflammation, ascites, endometriosis
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elevated CA 125

In which nonovarian neoplasms?

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Fallopian tube, endometrium, pancreas,breast, colon
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post-menopausal woman w palpable adnexal mass & CA 125> 65 U/mL

Dx?

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Ovarian malignancy ( epithelial, non-mucinous)

PPV >95%

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Serum markers for breast Ca
answer

CA27.29 (more sensitive &specific), CA15-3

--> different epitopes of a single Ag = protein product of breast ca assoc MUC1 gene

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elevated CA27.29/15-3

nonneoplastic causes?

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benign ovarian cysts, liver dz, benign breast dz

CA 15-3--> sarcoidosis and lupus

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elevated CA27.29

non-breast malignancies

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Colon, stomach, pancreas, prostate, lung
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Best prognostic markers in breast cancer
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IHC: ER, PR, Her-21 (c-erb-2) Nc staining % of tm cells

--> correlates well with biochemical assays (ligand binding)

1IHC & / FISH -->Rx: trastuzumab

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Her-2 assesment in breast cancer
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IHC:Only membranous staining-->only Inv. component

0-3+ --> 2+ => FISH

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Best marker for pancreticobiliary adenoca and assesment to treatment response
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CA19-9 >10001 U/L

1not seen in benign dz ( <100 U/L)

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CA 19-9

What type of Ag

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 = Lewis blood group Ag

not produced by Le- people

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AFP - physiologic effect

Site of synthesis?

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Major component of fetal serum --> ~ albumin

Yolk sac, fetal liver/GI tract

undetectable-->post partum, adults < 5.4ng/mL

benign conditions < 100 ng/mL

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AFP and malignancy
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Yolk sac tm--> [AFP] ~ prognosis

HCC -->[AFP] ~ overlap w benign dz

Hepatoid variant of gastric Ca

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low level elevation of hCG in non-pregnant woman
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Marijuana use
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Marker for monitoring transplant rejection
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beta2-Micoglobulin --> surface-most nucleated cells

-->non-covalent link to MHC I

Increased cell turnover1 => elevated beta2M2

1solid tm & hematolymphoid neoplasms,2renal isufficiency

question

Raised Alkaline Phosphatase

Causes

answer

-->osteoblastic activity (osteogenic sarcoma, bone mets,

active Paget disease of bone)

~ Liver function--> hepatic mets (carcioids~prognosis)

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Pt with gonadal/urologic cancer and elevated placental-type alkaline phosphatase
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Regan isoenzyme of Alk Phos
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modest quantity of 5-HT(serotonin), histamine, catecholamines &5-HTP

Dx: Tumor? Location?

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Carcinoid

Foregut: stomach, proximal duodenum and lung

 

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Only serotonin production in high quantities

Dx: Tumor? Location?

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Carcinoid

Midgut: distal duodenum,jejunum,ileum,appendix,right colon

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Carcinoid tumor

non secretory for indoles

Location?

answer

 

Distal 1/3 of transverse, descending colon,sigmoid colon and rectum

~hCG

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Most accurate marker for detection of carcinoid tm
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Platelet serotonin

--> take up serotonin from the serum @ constant rate

--> not affected by diet (tryptophan rich)

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Urine test

 elevated 5-HIAA

DDx:

answer

Carcinoid --> 20-30% ~ normal (foregut,hindgut)

False elevation--> tryptophan rich diet

5-HT--> platelets -->some 5-HT--> renal tubules => 5-HIAA

question

Plasma marker in neuroendocrine tm

--> Tm burden and treatment response

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Chromogranin A

Small cell NE, pheo,carcinoid,islet cell tm

 

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Increased [Calcitonin]plasma

DDx?

answer

MTC

Hashimoto, C-cell hyperplasia, breast ca

20 -->chronic renal failure, Zollinger-Ellison syndrome

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[Calcitonin]plasma < 10ng/L

more sensitive test?

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provocative testing - pentagastrin/omeprazole/Ca++

--> in MEN II families

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MTC

Marker of worse prognosis

answer
high CEA => greater de-differentiation
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Tumor with secretion of:

Epinephrine & norepinephrine

Dx?

answer

Pheochromocytoma--> adrenal medulla --> norepinephrine --PNMT-->epinephrine

Extra-adrenal tm --> mainly norepinephrine

question

Urinary VMA

DDx?

answer

Paraganglioma1/Pheochromocytoma2/ Neuroblastoma3

--> fractionation of catecholamines/metanephrines

1norepinephrine--> normetanephrine --> VMA

2epinephrine--> metanephrine --> VMA

3also homovanillic acid--> metabolic product of DOPA & dopamine

question

Most accurate test for initial screening of

tumors of chromaffin cells

answer

1.free Metanephrineplasma

2. Metanephrine/Catecholamineurine

plasma catecholamines --> poor sensitivity --> episodic release

plasma metanephrines--> long term catecholamine secretion

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free Metanephrineplasma Metanephrine/Catecholamineurine

--> equivocal results --> ?test to clarify tests?

answer
Clonidine suppression test
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low VMA:HVA and prognosis
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<-- poorly difeerentiated Neuroblastoma

=> worse prognosis

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Monitoring of patients w known hx/o urothelial Ca

Marker? DDx of + results

answer

urinary NMP22--> sensitive,nonspecific (1-6wks post Sx)

Inflammation-->rapid cell turnover --> false +

Leukocytes--> false +

question

Bladder tumor antigen

false +

answer
Stone disease, inflammation, BPH
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Urine test for Prostatic adenoCa
answer

PCA3/DD3

RNA fro urine sediment--> quantitative real time PCR

=> # DD3 RNA transcripts (nontranslated mRNA)

question

elevated [PSA]serum 1 in prostatic adenoca

Cause?

answer

1Increase leakage into the extracellular matrix

KLK3 gene (encodes PSA) --> not upregulated in Prostate adenoca 

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