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3.2 Coordination and control – the endocrine system

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Question 3

Doctors can diagnose subclinical hypothyroidism by measuring the level of Thyroid Stimulating Hormone (TSH) in a patient's blood.

  • If the TSH level is strictly above 4.5 mU/L4.5\text{ mU/L}4.5 mU/L, this suggests the patient may have hypothyroidism.
  • A patient has her TSH levels monitored monthly over a six-month period as shown in the table below:
MonthTSH level (mU/L\text{mU/L}mU/L)
July4.8
August4.2
September4.5
October5.1
November4.4
December5.3
a.

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

[2]
b.

Suggest two further steps or laboratory investigations the doctor should take to confirm whether the patient has permanent hypothyroidism.

[2]
c.

The doctor discusses a treatment option called levothyroxine (thyroid hormone replacement) with the patient, providing her with the following information:

Information about Levothyroxine treatment:

  • Benefits: Relieves symptoms such as fatigue, weight gain, and cold intolerance. Reduces the risk of developing high cholesterol.
  • Risks/Considerations:
    • Can cause bone thinning (osteoporosis) if the dose is too high, especially in postmenopausal women.
    • Increases the risk of an irregular heart rate (atrial fibrillation) in patients over the age of 65.
    • Requires life-long periodic blood tests to monitor thyroid levels and adjust doses.

The patient is a 68-year-old female with mild fatigue who has a strong family history of osteoporosis.

Discuss the factors this specific patient should consider when making her decision about whether to start levothyroxine treatment.

[4]
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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