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3.2 Coordination and control – the endocrine system

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Question 2

Doctors can determine if a patient is developing primary hypothyroidism (an underactive thyroid) by measuring the level of thyroid-stimulating hormone (TSH) in their blood.

  • If the TSH level goes above 4.5 mIU/L4.5\text{ mIU/L}4.5 mIU/L, this indicates that primary hypothyroidism may have started.

A patient has her TSH levels measured each month for six months:

  • January: 4.8 mIU/L4.8\text{ mIU/L}4.8 mIU/L
  • February: 4.2 mIU/L4.2\text{ mIU/L}4.2 mIU/L
  • March: 4.5 mIU/L4.5\text{ mIU/L}4.5 mIU/L
  • April: 5.3 mIU/L5.3\text{ mIU/L}5.3 mIU/L
  • May: 4.5 mIU/L4.5\text{ mIU/L}4.5 mIU/L
  • June: 4.7 mIU/L4.7\text{ mIU/L}4.7 mIU/L
a.

Calculate the percentage of these six monthly readings that are above the threshold of 4.5 mIU/L4.5\text{ mIU/L}4.5 mIU/L.

[2]
b.

What evidence is there from the data to suggest this patient may have started to develop primary hypothyroidism?

[1]
c.

Suggest two different types of further evidence the doctor could collect to confirm if she has primary hypothyroidism.

[2]
d.

The doctor discusses Levothyroxine replacement therapy with the patient and provides her with the following leaflet:

Information about Levothyroxine Therapy

  • Benefits of Levothyroxine: Levothyroxine relieves common hypothyroid symptoms such as severe fatigue and feeling cold, and it prevents long-term complications such as high cholesterol and goitre.
  • Risks of Levothyroxine:
    1. Levothyroxine can exacerbate cardiac arrhythmias or angina, particularly in patients with pre-existing coronary artery disease.
    2. Over-treatment with Levothyroxine can accelerate bone density loss (osteoporosis), especially in postmenopausal women.
    3. Absorption of the hormone is significantly reduced if taken alongside iron or calcium supplements.

The patient is a 72-year-old postmenopausal woman who has chronic angina and is suffering from severe fatigue and high cholesterol.

Discuss the benefits and risks this specific patient should consider when deciding whether to start Levothyroxine therapy.

[3]
Markscheme

3.2 Coordination and control – the endocrine system Questions

  1. GCSE
  2. /Biology
  3. /3.2 Coordination and control – the endocrine system

23 exam-style questions on OCR GCSE Biology 3.2 Coordination and control – the endocrine system, covering 3.2.1 Principles of hormonal coordination and control, 3.2.2 Roles of thyroxine and adrenaline, 3.2.3 Hormones in human reproduction, 3.2.4 Interactions of reproductive hormones, 3.2.5 Hormones in contraception, 3.2.6 Hormones in reproductive technologies, 3.2.7 Plant hormones in growth and coordination, 3.2.8 Effects of plant hormones, and 3.2.9 Uses of plant hormones. Each one has a worked solution and a mark scheme showing where the marks go.

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