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Case-based large group learning

Total number of slides in presentation: 22

3 case scenarios – each presenter will get 4 min

Last 10 min is for application and summary

Total duration of lecture: 40 to 45 min

Post-test at the end to conclude the chapter: Duration 10 min

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At the end of the lecture class the learner must be able to:

List the tests done to assess gastric, pancreatic and thyroid function

Categorise the function tests and their importance

Apply them in clinical situations

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Assessment of Gastric functions Fractional Test Meal (FTM)

- requires aspiration of gastric contents

- aspiration: ‘Ryle’s tube’ Pentagastrin Stimulation Test

- synthetic ‘peptide’

- having biological active sequence of gastrin Augmented Histamine test

- Most potent stimulus of gastric secretion Serum Gastrin level

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Pentagastrin Stimulation Test Fasting gastric juice is aspirated by Ryle’s tube

→ ‘Residual juice’ Gastric juice collected for next one hour is

collected → ‘Basal secretion’ Gastric secretion is stimulated by giving

‘pentagastrin’ Dose: 6mg/Kg body weight Gastric secretion is collected every 15 min for

next one hour

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Pentagastrin Stimulation Test Normal Response by assessment of free and

total acidity:

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Trait Men Women

Basal Acid Output 0 to 10 mmol/hr 0 to 5.5 mmol/hr

Maximal Acid Output 7 to 45 mmol/hr 5 to 30 mmol/hr

Peak Acid Output 12 to 60 mmol/hr 8 to 40 mmol/hr

Clinical Application – Gastric functions

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Hyperacidity HypoacidityDuodenal ulcer Gastritis

Gastric cell hyperplasia Gastric carcinoma

Carcinoid tumours Partial gastrectomy

Zollinger-Ellison syndrome Pernecious anaemia

Multiple Endocrine Neoplasia – Type 1 Chronic iron deficiency anaemia

Basophilic leukemia

Classification – Thyroid Function Test Based on Thyroid Function & Clinical Utility

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Group I Primary function of thyroid

Radio-iodine uptake T3 – suppression testTSH – stimulation testTRH stimulation test

Group II Measurement of blood levels of thyroid hormones

Total T3 and T4 levelsFree T3 and Free T4 levelsCirculating TSH levelPlasma tyrosine level

Group III Metabolic effects of Thyroid hormones

Basal Metabolic RateSerum cholesterol levelSerum creatine levelSerum uric acid levelSerum creatine kinase level

Group IV Immunological tests for auto-immune disorders

Agar gel diffusion testComplement fixation test

Tests based on primary function of thyroid Radioactive ‘Uptake’ studies I131 → ‘tracer’ used for thyroid studies Normal: 20 to 40% TSH – stimulation test Basal levels of thyroid hormones is measured 3 injections of TSH each of 5 USP units is given 8

hourly Failure to produce thyroid hormones → Primary

hypothyroidism Stimulation of gland by production of thyroid

hormones → secondary hypothyroidism9

A 50 year school teacher came with the complaints of coarse speech, dry skin, puffy face, non-pitting pedal edema, easy fatigability and constipation. Personal history suggested she had noticed gaining weight despite decreased appetite over the past few months. O/E patient had a palpable swelling in front of the neck with brittle nails.

What is your probable diagnosis? Suggest the biochemical investigations to confirm

your diagnosis.10

Measurement of blood levels of thyroid hormones

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Hormone Method Reference Range

Total T4 ELISAChemiluminescenceRadioimmunoassay

5 to 12 µg/dl

Total T3 120 to 190 ng/dl

TSH 0.5 to 4.5 mIU/ml

Free T3 Chemiluminescence 0.2 to 0.5 ng/dl

Free T4 0.7 to 1.8 ng/dl

Plasma Tyrosine 60 to 70 µ Mol/L

A 49 year old female came to the medical OPD with complaints of intolerance to heat, loss of weight in spite of good appetite and excessive sweating. She also complained of excessive hair loss. O/E patient has protruding eyes and tremors of hands.

What is your probable diagnosis? Suggest the biochemical investigations to confirm

your diagnosis.

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Clinical Application of Thyroid Hormone Measurement

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Disorder Causes Thyroid profile Levels

Primary Hypothyroidism

CongenitalRadiation damageSurgical removalViral infectionAuto-immune

T3T4

TSH

↓↓↑

Secondary Hypothyroidism

Damage to the pituitary gland

T3T4

TSH

↓↓↓

Hyperthyroidism Graves diseaseToxic adenomaMulti-nodular goitreThyroid hormone overdose

T3T4

TSH

↑↑↓

Tests based on metabolic effects of thyroid gland

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Parameter Measurement & Normal Levels

Clinical Application

Basal Metabolic Rate (BMR)

Benedict Roth apparatusNormal: - 15 to + 20

5 to +20% → Normal-10 to + 10% → Euthyroid< - 20% → Hyperthyroid+ 50% to +75% → Hyperthyroid

Serum total cholesterol

Zak’s methodCholesterol oxidase methodNormal: 150 to 200 mg%

↑↑↑ levels → hypothyroidismNormal or lower limit of normal → Hyperthyroidism

Serum creatine HPLCNormal: 0.6 to 1 mg%

> 1.6 mg% → hyperthyroidism

Serum uric acid Uricase methodNormal: 3 to 7 mg%

↑ levels → myxoedema

Serum Creatine kinase

EnzymaticNormal: 38 to 300 U/L

↑ levels → hypothyroidism

Immunological tests for thyroid functions

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Anti-thyroid antibodies• anti-TG antibodies → attack thyroglobulin• anti-thyroperoxidase, or anti-TPO → attack

thyroperoxidase• TSH receptor antibodies Antithyroid antibodies are present in ‘Hashimoto’s

disease’ Antithyroid antibodies are detected in blood by:

- hemeagglutination

- RIA

A 50 year old man who was a chronic alcoholic was admitted to the casualty with the complaints of severe epigastric pain & vomiting. Symptoms started following consumption of a large meal after alcohol intake. O/E he had mild fever with tenderness in the upper abdominal region.

What is your probable diagnosis? Suggest the biochemical investigations to confirm

your diagnosis.

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Pancreatic Function Tests Exocrine functions: Secretin test Dimethadione test (DMO test) Triolein breath test Pancreatic insufficiency Para amino benzoic acid (PABA) test Faecal fat test Enzymes: Amylase and lipase Endocrine function Oral GTT

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Pancreatic Enzymes• Amylase– only digestive enzyme secreted by the pancreas in

an active form– functions optimally at a pH of 7– hydrolyzes starch and glycogen to glucose, maltose,

maltotriose, and dextrins– Reference Range: 50 to 120 U/L

• Lipase– function optimally at a pH of 7 to 9– emulsify & hydrolyze fat in the presence of bile salts– Reference Range: 50 to 175 U/L

Gastric, Pancreatic and Thyroid Function Test - Summary

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Synthetic peptide used to stimulate gastric secretion

Pentagastrin

Primary function of thyroid assessment Radioactive iodine – I131

Decrease in T3, Decrease in T4 & Increase in TSH

Primary hypothyroidism

Increase in T3, Increase in T4 & Decrease in TSH

Hyperthyroidism

Anti-thyroid antibodies Hashimoto’s thyroiditis

Amylase and lipase levels Pancreatitis

Examination Tips

• Thyroid function test

• Pentagastrin test• Pancreatic function test

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POST TEST

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