GI Flashcards

1
Q

Duration of acute, persistent, chronic diarrhoea

A

<2w
2~4w
>1m

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2
Q

Equation for stool osmolar gap

A

290 - 2 ⨉ ([Na]s + [K]s)

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3
Q

Compare chronic secretory and osmotic diarrhoea

A

secretory: persist with fasting, ↓ stool osmolar gap
osmotic: cease with fasting, ↑ stool osmolar gap

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4
Q

Which test is used to differentiate inflammatory diarrhoea from others?

A

faecal calprotectin

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5
Q

Which test is used to test for exocrine pancreatic insufficiency?

A

faecal elastase

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6
Q

Indications of positive hydrogen breath test (2)

A

sugar malabsorption
small intestine bacterial overgrowth

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7
Q

What is coeliac disease?

A

autoimmune, inflammatory disorder triggered by gluten intake

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8
Q

Gene for cystic fibrosis

A

CFTR

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9
Q

Origins of ALP (5) (how to differentiate?)

A

liver, bone, placenta, small intestine, kidney
(isoenzyme electrophoresis)

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10
Q

Which liver enzyme is raised significantly in chronic alcoholism & anti-convulsant intake?

A

GGT (γ-glutamyl transpeptidase)

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11
Q

How does cirrhosis lead to ↑ globulin?

A

↓ liver function –> ↓ degradation of gut antigens –> ↑ monomeric / plasma IgA

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12
Q

RR for serum amylase

A

30~100

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13
Q

Which level of elevated serum amylase is sensitive for acute pancreatitis? Which is diagnostic?

A

300 (3 ⨉ ULN)
1000

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14
Q

FP for serum amylase

A

PPU, peritonitis, DKA, macroamylasemia

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15
Q

DDx for persistent elevation of serum amylase

A

pancreatic pseudocyst, macroamylasemia, (chronic pancreatitis)

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16
Q

Pathophysiology and diagnosis of macroamylasaemia

A

amylase bound to other macromolecules ==> macroamylase –> ↓ excretion

amylase clearance <1%

17
Q

Usage of serum lipase

A

diagnosis of acute pancreatitis, esp. for delayed presentation

(longer half-life, normalise in 2w, compared with 3~5d for serum amylase)

18
Q

Urea breath test procedure

A
  • oral urea with carbon radioisotope
  • urease from H. pylori will produce ammnonia & labelled CO2
  • testing for labelled CO2 in patient’s breath
19
Q

Tests for H. pylori

A
  1. Urea breath test
  2. Rapid urease test / CLO test
  3. Histology
20
Q

Screening tests for CRC (2) (what is the regimen in HK? Interval, age indication)

A
  1. Guaiac-based faecal occult blood test
  2. Faecal immunochemical test [HK, Q2Y if -ve, 50~75]
21
Q

Compare gFOBT and FIT mechanism

A

gFOBT: detect peroxidase reaction
FIT: detect Hb with anti-human Hb IgG

22
Q

FP and FN for gFOBT

A

FP: red meat
FN: vitamin C