Case Study

CASE STUDY ANSWERS: Sally Shell — Type 1 Diabetes Mellitus

1. What are the signs and symptoms of type I diabetes mellitus shown in Sally’s case?

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• Polyuria (frequent urination)

• Polydipsia (constant thirst)

• Polyphagia (constant hunger)

• Weight loss despite eating

• Fatigue

• Pale, dry skin

• Irritability and difficulty concentrating

• Increased respiratory and pulse rates

• Positive ketones in urine

• Elevated blood glucose (22 mmol/L)

Rationale:

2. What is the etiology of type I diabetes mellitus?

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• Autoimmune destruction of pancreatic beta cells → leads to absolute insulin deficiency.

• May be triggered by:

  • Genetic predisposition

  • Viral infections (e.g., coxsackievirus)

  • Environmental factors (unknown exact cause)

Rationale:

3. What was the most likely cause of Sally’s polyuria and weight loss before her hospitalization?

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• Polyuria: High blood glucose levels cause osmotic diuresis (sugar pulls water into the urine) → frequent urination.

• Weight loss: No insulin = glucose can't enter cells → body burns fat and muscle for energy.

Rationale:

4. After Sally has learnt how to regulate her insulin pump, when should she decrease the rate of insulin injection?

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• Before exercise or physical activity (e.g., sports training, running)

• During times of decreased food intake (e.g., illness, reduced appetite)

Rationale:

5. What are Sally’s symptoms when she forgets to readjust her insulin pump most likely a result of?

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• Hypoglycemia (low blood sugar)

Symptoms she showed:

• Difficulty concentrating

• Irritability

• Blurred vision

Rationale:

6. Why did Sally develop acidosis?

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• She stopped taking insulin while she was sick → no glucose could enter cells → body broke down fat for energy → production of ketones → ketones accumulate in blood → metabolic acidosis (Diabetic Ketoacidosis - DKA).

Rationale:

7. The first manifestation of renal dysfunction for Sally is most likely to be?

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• Microalbuminuria
  (small amounts of protein [albumin] in urine)

Rationale:

✏ QUICK RATIONALE SUMMARY

CASE STUDY 2: Mrs R — Graves' Disease

1. What is the most likely cause of Mrs R’s increased thyroid function?

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• Graves' disease is an autoimmune disorder where the immune system produces thyroid-stimulating immunoglobulins (TSI).

• These antibodies stimulate the thyroid gland to produce excessive T3 and T4 hormones.

Rationale:

2. What explains the physiological mechanism(s) in Mrs R’s oversecretion of thyroid hormones?

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• Autoantibodies (TSI) mimic thyroid-stimulating hormone (TSH) → bind to TSH receptors on the thyroid gland → constant activation of hormone production.

• This leads to hyperplasia (enlargement) of the thyroid (seen as a neck mass/goitre) and excessive release of T3 and T4 into the bloodstream.

Rationale:

3. Which of the symptoms experienced by Mrs R may not resolve with treatment of her hyperthyroidism?

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• Exophthalmos (bulging eyes) may not fully resolve.

• Eye changes are caused by inflammation and swelling of eye tissues, not just thyroid hormone levels.

Rationale:

4. Why has Mrs R. lost weight?

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• Excess T3 and T4 hormones increase basal metabolic rate (BMR).

• This causes rapid calorie burning even at rest, leading to weight loss despite an increased appetite.

Rationale:

5. Which pathophysiological mechanisms account for the majority of her symptoms?

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• Excessive circulating thyroid hormones (T3 and T4) increase metabolism and sympathetic nervous system activity.

Major effects causing symptoms:

• Increased heart rate → palpitations, pounding heart

• Increased gastrointestinal motility → diarrhea

• Increased nervous system sensitivity → irritability, restlessness, anxiety

• Increased thermogenesis → feeling hot, sweating

• Protein and fat breakdown → weight loss, muscle weakness

• Eye tissue swelling → bulging eyes (exophthalmos)

Rationale:

✏ QUICK RATIONALE SUMMARY