Immunology Investigations Quiz

Study Notes

Investigations

Immunology

Antibodies to a-gliadin (AGA) are less sensitive, not recommended for diagnostics.
Anti-endomysial antibody (EMA) [IgA] has 90-95% sensitivity and specificity for diagnosing coeliac disease.
Anti-tissue transglutaminase antibodies (tTG) are preferred for screening due to high sensitivity and specificity.
In patients with IgA deficiency, IgG antibodies are utilized.

Hematology

Iron deficiency anemia occurs in 50% of cases, typically presenting as microcytic and hypochromic anemia.
Coexisting iron deficiency anemia can lead to dimorphic anemia, which features both microcytic and macrocytic red blood cells.

Features of Hyposplenism

Characteristic findings include hypersegmented polymorphonuclear leucocytes, Heinz bodies, and Howell-Jolly bodies.
Prothrombin time (PT) may be prolonged in affected individuals.

Biochemistry

Hypoalbuminemia indicates low serum albumin levels.
Hypocalcemia is commonly associated with vitamin D deficiency.
Hypocholesterolemia reflects low cholesterol levels.
Low serum carotene levels are noted.

Intestinal Biopsy

Duodenal/jejunal biopsy is the gold standard for diagnosing coeliac disease.
Villous atrophy is a key histological feature, which typically improves on a gluten-free diet.

Bone Densitometry (DXA)

Recommended for all patients due to the elevated risk of osteoporosis.

Electrolyte Imbalances

Common imbalances include hypokalemia, hypocalcemia, and hypomagnesemia.
Metabolic acidosis is also a potential complication.

Oral Glucose Tolerance Tests

Important to assess glucose metabolism in affected patients.

Excretion of Breath Hydrogen

Elevated levels may occur due to bacterial fermentation of unabsorbed lactose in coeliac sprue.

Oral D-Xylose Tolerance Test

Helps identify carbohydrate malabsorption.
D-xylose is absorbed in the proximal small intestine and excreted unchanged in urine.
In untreated coeliac sprue, urinary D-xylose excretion and peak blood xylose levels are decreased.

Treatment and Management

Main treatment involves adhering to a gluten-free diet.
Gluten-free diet includes rice, potatoes, and corn (maize).
Wheat, rye, barley, and oats can potentially be reintroduced in small amounts after monitoring for symptoms.
Patients with excellent clinical responses may require repeat jejunal biopsies.
Some patients may not achieve remission and could be refractory to treatment.
Surgical resection may be necessary in rare cases.

Prognosis and Complications

Risk of enteropathy-associated T-cell lymphoma.
Increased likelihood of squamous carcinoma of the small bowel.
Occurrence of ulcerative jejunoileitis.
Symptoms may include fever and metabolic bone disease.
Diagnosis of small bowel cancer can be particularly challenging.

Description

Test your knowledge on immunological investigations, focusing on antibodies related to coeliac disease. This quiz covers key aspects such as the sensitivity and specificity of various antibodies like EMA and tTG. Understanding the importance of these antibodies is crucial for accurate diagnosis and screening.

Immunology Investigations Quiz

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Questions and Answers

What is the most useful antibody test for diagnosing coeliac disease?

What laboratory finding is characteristic of microcytic and hypochromic anemia?

Which of the following is a gold standard method for diagnosing coeliac disease?

Which of the following is NOT typically included in a gluten-free diet?

What specific feature may be seen in the blood of patients with hyposplenism?

Which complication is associated with untreated coeliac disease?

In patients with both iron deficiency anemia and macrocytic red blood cells, what is the expected anemia type?

Which of the following findings suggests vitamin D deficiency?

What is a potential test to assess carbohydrate malabsorption in patients?

Which electrolyte imbalance is commonly observed in untreated coeliac disease?