LACTASE DEFICIENCY

TEST-BASED MCQs · FMGE / NEET-PG REVISION

10 MCQs · A4 · 3×2

MCQ 01–06

3 rows × 2 columns

MCQ 01

The most useful non-invasive test for suspected lactose malabsorption is:

A. Serum amylase

B. Hydrogen breath test after lactose load

C. Schilling test

D. Fecal occult blood test

MCQ 02

A positive lactose hydrogen breath test is caused by:

A. Hepatic urea formation

B. Colonic bacterial fermentation

C. Gastric hydrogen secretion

D. Pulmonary lactose excretion

MCQ 03

Which stool result supports carbohydrate malabsorption?

A. Alkaline stool; high fat

B. Acidic stool; reducing substances

C. Blood; high calprotectin

D. Normal pH; occult blood

MCQ 04

Lactose malabsorption on a lactose tolerance test is suggested by:

A. Marked glucose rise

B. Minimal or absent glucose rise

C. Increased bilirubin

D. Decreased amylase

MCQ 05

Symptoms cease on lactose withdrawal and recur on rechallenge. This supports:

A. Lactose intolerance

B. Milk-protein allergy only

C. Chloride diarrhea

D. Pancreatic insufficiency

MCQ 06

A preterm infant has transient diarrhea and distension with milk feeds. The likely basis is:

A. Developmental lactase deficiency

B. Permanent pancreatic failure

C. Congenital chloride diarrhea

D. Biliary atresia

Page 1 of 2Tests → mechanism → interpretation

MCQ 07–10

3 rows × 2 columns

MCQ 07

Which finding makes isolated lactase deficiency less likely?

A. Flatulence after milk

B. Watery acidic stool

C. Bloody stool with eczema

D. Dose-related symptoms

MCQ 08

Hydrogen becomes detectable in breath after lactose because:

A. Lactase enters exhaled air

B. Colonic bacteria produce H₂

C. Stomach directly produces H₂

D. Glucose blocks ventilation

MCQ 09

Symptoms resolve with lactose reduction and reproducibly recur after reintroduction. This:

A. Supports lactose intolerance

B. Confirms inflammatory bowel disease

C. Proves IgE allergy

D. Excludes malabsorption

MCQ 10

A child has secondary lactase deficiency due to celiac disease. The priority is:

A. Treat mucosal disease; temporarily reduce lactose if needed

B. Avoid all dairy lifelong

C. Lifelong pancreatic enzymes

D. Suppress colonic bacteria

PRINTING SPACE

Page 2 of 2Secondary deficiency may be reversible

Answer Key + One-Liners

Check only after attempting both pages.

01 · B
Breath H₂ detects fermentation of unabsorbed lactose.

02 · B
Colonic bacteria generate hydrogen.

03 · B
Organic acids lower stool pH; sugars remain reducing.

04 · B
Failure to hydrolyze lactose blunts the glucose rise.

05 · A
Elimination–rechallenge shows reproducible intolerance.

06 · A
Preterm lactase activity may be developmentally low.

07 · C
Blood plus eczema favors cow’s-milk protein allergy.

08 · B
Colonic H₂ is absorbed and then exhaled.

09 · A
Withdrawal and rechallenge support clinical intolerance.

10 · A
Treat villous injury; lactose restriction is often temporary.

Exam trap: A positive breath test demonstrates lactose malabsorption. Symptoms after exposure establish lactose intolerance.

Print using A4 portrait, default margins, and scale-to-fit.

Lactase Test MCQs