Материал: 100_Cases_in_Clinical_Medicine
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CASE 21: TIREDNESS
History
A 55-year-old man presents to his general practitioner (GP), complaining of lack of energy. He has become increasingly tired over the past 18 months. He works as a solicitor and describes episodes where he has fallen asleep in his office. He is unable to stay awake after 9.30 pm, and sleeps through until 7.30 am. He finds it difficult to concentrate at work, and has stopped playing his weekly game of tennis. He had an episode of depression 10 years ago related to the break-up of his first marriage. He has no current personal problems. He has had no other major illnesses. His brother developed type 1 diabetes mellitus at the age of 13. On direct questioning, he has noticed that he has become more constipated but denies any abdominal pain or rectal bleeding. He has put on 8 kg in weight over the past year.
Examination
On examination he is overweight. His facial skin is dry and scaly. His pulse is 56/min, regular and blood pressure 146/88 mmHg. Examination of his cardiovascular, respiratory and abdominal systems is unremarkable. Neurological examination was not performed.
INVESTIGATIONS
|
|
Normal |
Haemoglobin |
10.3 g/dL |
13.3–17.7 g/dL |
Mean corpuscular volume (MCV) |
92 fL |
80–99 fL |
White cell count |
4.3 % 109/L |
3.9–10.6 % 109/L |
Platelets |
154 % 109/L |
150–440 % 109/L |
Sodium |
140 mmol/L |
135–145 mmol/L |
Potassium |
4.4 mmol/L |
3.5–5.0 mmol/L |
Urea |
6.4 mmol/L |
2.5–6.7 mmol |
Creatinine |
125 &mol/L |
70–120 &mol/L |
Glucose |
4.7 mmol/L |
4.0–6.0 mmol/L |
Calcium |
2.48 mmol/L |
2.12–2.65 mmol/L |
Phosphate |
1.20 mmol/L |
0.8–1.45 mmol/L |
Cholesterol |
6.4 mmol/L |
3.9–6.0 mmol/L |
Triglycerides |
1.4 mmol/L |
0.55–1.90 mmol/L |
Urinalysis: nothing abnormal detected (NAD)
Questions
•What is the likely diagnosis?
•How would you further examine, investigate and manage this patient?
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ANSWER 21
Fatigue is a very common symptom of both physical and mental illness. The differential diagnosis is extensive and includes cancer, depression, anaemia, renal failure and endocrine diseases. In this case the main differential diagnoses are depression and hypothyroidism. He has a past history of depression, but currently has no obvious triggers for a further episode of depression. He is not waking early in the morning or having difficulty getting to sleep, which are common biological symptoms of severe depression. There are a number of clues in this case to the diagnosis of hypothyroidism. Insidious onset of fatigue, difficulty concentrating, increased somnolence, constipation and weight gain are features of hypothyroidism. As in this case there may be a family or past medical history of other autoimmune diseases such as type 1 diabetes mellitus, vitiligo or Addison’s disease. Hypothyroidism typically presents in the fifth or sixth decade, and is about five times more common in women than men. Obstructive sleep apnoea is associated with hypothyroidism and may contribute to daytime sleepiness and fatigue.
On examination the facial appearances and bradycardia are consistent with the diagnosis. Characteristically patients with overt hypothyroidism have dry, scaly, cold and thickened skin. There may be a malar flush against the background of the pale facial appearance (‘strawberries and cream appearance’). Scalp hair is usually brittle and sparse, and there may be thinning of the lateral third of the eyebrows. Bradycardia may occur and the apex beat may be difficult to locate because of the presence of a pericardial effusion. A classic sign of hypothyroidism is the delayed relaxation phase of the ankle jerk. Other neurological syndromes which may occur in association with hypothyroidism include carpal tunnel syndrome, a cerebellar sydrome or polyneuritis. Patients may present with psychiatric illnesses including psychoses (‘myxoedema madness’).
Clues to the diagnosis in the investigations are the normochromic, normocytic anaemia, marginally raised creatinine, and hypercholesterolaemia. The anaemia of hypothyroidism is typically normochromic, normocytic or macrocytic; microcytic anaemia may occur if there is menorrhagia. A macrocytic anaemia may represent undiagnosed vitamin B12 deficiency. Renal blood flow is reduced in hypothyroidism, and this can cause the creatinine to be slightly above the normal range.
The most severe cases of hypothyroidism present with myxoedema coma, with bradycardia, reduced respiratory rate and severe hypothermia. Typically, shivering is absent.
In this case the thyroid function tests were as follows: thyroid-stimulating hormone (TSH) 73 mU/L (normal range: !6 mU/L); free thyroxine (T4) 3 pmol/L (normal range 9–22 pmol/L). The high TSH indicates primary hypothyroidism rather than hypopituitarism. The most common cause of hypothyroidism is autoimmune thyroiditis and the patient should have thyroid autoantibodies assayed.
!Causes of hypothyroidism
•Panhypopituitarism
•Autoimmune thyroiditis
•Post-thyroidectomy
•Post-radio-iodine treatment for thyrotoxicosis
•Drugs for treatment of hyperthyroidism: carbimazole, propylthiouracil
•Amiodarone, lithium
•Dietary iodine deficiency
•Inherited enzyme defects
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Treatment is with T4 at a maintenance dose of 75–200 &g/day. Response is measured clinically and biochemically by the return of TSH to the normal range. Elderly patients or those with coronary heart disease should be started cautiously on T4 because of the risk of precipitating myocardial ischaemia.
KEY POINTS
•Hypothyroidism should be considered in the differential diagnosis of any patient presenting with fatigue.
•A neurological examination should be part of the routine assessment of such patients.
•Clinical symptoms of hypothyroidism are usually non-specific.
•Hypothyroidism may present in unusual ways such as psychoses or decreased conscious level.
•Autoimmune thyroiditis is the commonest cause of hypothyroidism.
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