Thyroid


Summary of Common Conditions in OSCEs


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The three main pathologies likely to appear in the examination are as follows:



  • Thyroglossal cyst
  • Hyperthyroidism
  • Hypothyroidism

Patients with hyper- or hypothyroidism may be brought to the examination, but it is equally likely that these conditions will be simulated by actors (particularly in short-station OSCEs). Simulating the signs of hyperthyroidism (e.g. tremor, irritability/fidgeting, ophthalmoplegias, heat intolerance) is particularly easy for well-trained actors. Therefore it is very important to inspect for subtle signs such as restlessness, frequent yawning, over- or underweight body habitus and tremor from the end of the bed as these signs can instantly give away the diagnosis.



Figure 9.1 Multinodular goitre: (a) frontal and (b) lateral view. Remember that patients with a goitre may have hyperthyroidism or hypothyroidism, or may be euthyroid. This patient was euthyroid


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Figure 9.2 After successful resection of the goitre


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Key Investigations



  • Thyroid function tests: Free thyroxine and triiodothyronine levels are more useful than total levels.
  • Thyroid autoantibodies: Anti-thyroid peroxidase may be increased in Hashimoto’s and Graves diseases. Its presence in Graves disease signifies an increased likelihood of post-treatment hypothyroidism.
  • Thyroid-stimulating hormone receptor antibody: Increased in Graves disease.
  • Blood lipids and glucose: Patients with hypothyroidism are at risk of cardiovascular disease and diabetes.
  • Ultrasound scan: Useful to distinguish cystic from solid lumps (which are more likely to be malignant).
  • Isotope scan: Can be used to differentiate different causes of a goitre and identify ectopic thyroid tissue and hot and cold nodules. Note that cold nodules are much more likely to be malignant than hot nodules.

Key Treatment Modalities for Thyroid Disease


Hyperthyroidism



  • Drugs:

    • Symptom control: beta-blockers, e.g. propranolol.
    • Disease modification: carbimazole + thyroxine (simultaneously) for 12–18 months. (NB. Agranulocytosis is a serious complication of carbimazole therapy.)

  • Radioiodine: This is contraindicated in active hyperthyroidism (due to an increased risk of thyrotoxic storm), pregnancy and breast-feeding.
  • Complete or partial thyroidectomy: This is reserved for cases refractory to medical treatment, compression of important structures, and patient preference for cosmetic reasons. (NB. Damage to local structures, including the recurrent laryngeal nerve and parathyroid glands, is a serious complication.)

Hypothyroidism


Treatment is with levothyroxine – but remember that:



  • Enzyme-inducing drugs increase the breakdown of levothyroxine
  • Thyroxine can increase the risk of a myocardial infarction in patients with ischaemic heart disease.

Hints and Tips for the Exam


Examination of the thyroid gland and thyroid function are very commonly tested in short- and long-station finals. Beware as there is a lot to do, especially in just 5 or 10 minutes. There is no ‘right’ or ‘wrong’ order in which to perform the examination, but it would be wise to dedicate most of your time examining the thyroid gland itself (as opposed to peripheral stigmata), especially if it appears abnormal in any way upon general inspection.


Performing a Slick Examination



  • Inspection from the end of the bed: Be quick! Have a system. For example, start with the bedside paraphernalia, then move on to the general body habitus and then on to the face.
  • Examining the thyroid gland: Do not forget to ask about pain and check for scars (even underneath necklaces and collars!). To palpate the gland, stabilise one lobe with one hand and palpate the other lobe with the other hand using the flat of your fingers. Once you have started palpating, try not to lift your hand off the neck until you finish palpating that lobe so that you do not miss small lumps. If you detect a lump, use the same protocol to describe it as you would for any other lump – comment on site, size, surface, texture, temperature, tenderness, consistency, pulsatility and adherence to any underlying or overlying structures. Specifically for thyroid lumps, you must also comment on whether they move with swallowing or tongue protrusion. It is extremely important to palpate the cervical lymph nodes. If you notice a lump, it may be wise to examine Pemberton’s sign.
  • Examining the hands: Again, be quick because this is probably the easiest part of the examination and could give you vital clues to the diagnosis. Look for tar staining because Graves eye disease is much more common in smokers.
  • Examining the legs: Expose the shins to look for pretibial myxoedema (Figure 9.3). When testing for proximal myopathy, sit the patient on the edge of the couch, and instruct them to fold their arms and then stand from the sitting position without using their hands. Remember that reflexes are slow-relaxing in hypothyroidism – the twitch is normal but relaxation back to the resting position afterwards is delayed.
  • Examining the eyes: If there is proptosis or exophthalmos, you should check that the eyes can be shut because inability to shut the eyes can result in corneal damage. To test lid lag, instruct the patient to keep their head still and follow your rapidly downwards-moving horizontal finger with the eyes only. It is sometimes necessary to place your other hand gently on the patient’s forehead to prevent head movements. To test for, test eye movements in an ‘H’ pattern (see Chapter 5 on the central nervous system) and on vertical upwards and downwards gaze. Ophthalmoplegia in hyperthyroidism is typically most marked on upwards gaze.

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May 17, 2017 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Thyroid

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