Clinical biochemistry: macroamylasaemia: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Clinical biochemistry: macroamylasaemia

Sample item

A 40-year-old man without abdominal pain has persistently raised serum amylase, but serum lipase is normal and urinary amylase excretion is low. What is the likely explanation?

AChronic pancreatitis with obstruction of the main pancreatic ductBMumps parotitis with release of salivary amylase into the bloodCMacroamylasaemia, with amylase bound to immunoglobulin and too large to be filteredDPerforated duodenal ulcer with leakage of pancreatic enzymes

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Macroamylasaemia, with amylase bound to immunoglobulin and too large to be filtered

In macroamylasaemia, amylase forms a complex with immunoglobulin or polysaccharide that is too large for glomerular filtration. Serum amylase stays high, urinary amylase is low and lipase is normal, and the condition is benign. Pancreatitis and other causes raise urinary amylase.

Option by option

A. Chronic pancreatitis with obstruction of the main pancreatic duct
Pancreatic disease would usually also raise lipase and cause symptoms.
B. Mumps parotitis with release of salivary amylase into the blood
Salivary amylase rises in mumps with a normal lipase but urinary amylase is raised.
C. Macroamylasaemia, with amylase bound to immunoglobulin and too large to be filtered (correct)
Correct. A large amylase-immunoglobulin complex is retained in the blood and not filtered.
D. Perforated duodenal ulcer with leakage of pancreatic enzymes
A perforation raises lipase as well and causes an acute abdomen.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is C, Macroamylasaemia, with amylase bound to immunoglobulin and too large to be filtered. In macroamylasaemia, amylase forms a complex with immunoglobulin or polysaccharide that is too large for glomerular filtration.

Why is "Chronic pancreatitis with obstruction of the main pancreatic duct" not the answer?

Pancreatic disease would usually also raise lipase and cause symptoms.

Why is "Mumps parotitis with release of salivary amylase into the blood" not the answer?

Salivary amylase rises in mumps with a normal lipase but urinary amylase is raised.

Why is "Perforated duodenal ulcer with leakage of pancreatic enzymes" not the answer?

A perforation raises lipase as well and causes an acute abdomen.

What concept does this question test?

It tests Clinical biochemistry: macroamylasaemia in Biochemistry. Serum amylase stays high, urinary amylase is low and lipase is normal, and the condition is benign. Pancreatitis and other causes raise urinary amylase.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Clinical biochemistry: macroamylasaemia?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.