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15 - Endocrine, metabolic and miscellaneous causes of diarrhoea
- Edited by Ranjit N. Ratnaike, University of Adelaide
- Foreword by Gary R. Andrews
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- Book:
- Diarrhoea and Constipation in Geriatric Practice
- Published online:
- 17 August 2009
- Print publication:
- 12 August 1999, pp 171-184
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- Chapter
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Summary
Diarrhoea may be a consequence of endocrine disorders, hormone-secreting tumours, metabolic illnesses and a variety of miscellaneous conditions.
Hyperthyroidism
Between 15 and 18 per cent of patients with thyrotoxicosis are above the age of 60 years. There is a female predominance of four to one.
Only about 25 per cent of elderly patients with thyrotoxicosis manifest the disease clinically. In the majority the presentation is that of ‘apathetic hyperthyroidism’ a term coined by Lahey in 1931, and characterized by lethargy and apathy, and the absence of eye signs and tachycardia. Cardiovascular effects such as atrial fibrillation and the attendent risk of embolism produce the most frequent and severe morbidity in this age group. Occasionally, diarrhoea attributed to gastrointestinal hypermotility may be the only symptom and of sufficient severity to cause dehydration and hypokalaemia. In a number of patients steatorrhoea is present. The mechanism is unknown.
Hypothyroidism
In the elderly patient the symptoms of hypothyroidism are insidious and may be present for years before the diagnosis is made. Constipation is the pre-eminent gastrointestinal symptom. Diarrhoea sometimes occurs and may be associated with malabsorption and steatorrhoea. Decreased intestinal motility and prolonged intestinal transit time could predispose to small intestinal bacterial overgrowth and diarrhoea (see Chapter 9).
Diabetes mellitus
Diabetes mellitus is common in the elderly. Diarrhoea in patients with diabetes mellitus is well documented, especially in those on insulin treatment with poorly controlled blood glucose or evidence of peripheral vascular disease and neuropathy. Diabetic diarrhoea is classically nocturnal, though not invariably so.
5 - The investigation of diarrhoea
- Edited by Ranjit N. Ratnaike, University of Adelaide
- Foreword by Gary R. Andrews
-
- Book:
- Diarrhoea and Constipation in Geriatric Practice
- Published online:
- 17 August 2009
- Print publication:
- 12 August 1999, pp 40-69
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- Chapter
- Export citation
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Summary
The diagnosis of diarrhoea, due to the numerous causative factors, requires a multidisciplinary investigative approach. This chapter deals with several investigative procedures and laboratory tests.
The sections in this chapter are not prioritized to reflect greater importance to a particular specialty. For example, the decision whether to first request a stool microscopy and culture to identify an enteric pathogen or to request a double contrast barium study depends on the clinical circumstances.
INVASIVE PROCEDURES
Ranjit N.Ratnaike
Sigmoidoscopy is an extremely rewarding investigation and should be regarded as mandatory before a barium enema is performed. Sigmoidoscopy may reveal the presence of a tumour, lesions suggesting inflammatory bowel disease, ulceration due to infectious colitis, or plaques characteristic of pseudomembraneous colitis. In patients with proven bacillary dysentery, sigmoidoscopy is an extremely painful procedure and is unnecessary. A high rectal swab should be sent for immediate examination if a parasitic infection, for example amoebic dysentery, is suspected.
In diarrhoea suggesting large bowel pathology (diarrhoea with blood and mucus), the choice of the initial investigation lies between a double contrast barium enema (DCBE) and colonoscopy. In a study of 76 patients with colonic disease, colonoscopy was more accurate, particularly in the diagnosis of inflammatory bowel disease, where DCBE missed the diagnosis in 9 (64 per cent) of 14 patients. The advantages of colonoscopy include the opportunities to obtain biopsies and remove polyps.