From the Guidelines
A 75-year-old patient presenting with constipation should only have a complete blood cell count (CBC) as the initial blood work, unless other clinical features warrant otherwise, as recommended by the American Gastroenterological Association 1. The rationale behind this recommendation is to avoid unnecessary testing, as metabolic tests such as glucose, calcium, and sensitive thyroid-stimulating hormone are not recommended for chronic constipation without other symptoms or signs 1. Key points to consider in the initial evaluation of constipation in the elderly include:
- A CBC to identify anemia or infection that may contribute to constipation
- Avoiding metabolic tests unless clinically indicated, as they are not recommended by the American Gastroenterological Association 1
- Considering a colonoscopy only if alarm features are present, such as blood in stools, anemia, or weight loss, or if age-appropriate colon cancer screening has not been performed 1
- Evaluating colonic transit if anorectal test results do not show a defecatory disorder or if symptoms persist despite treatment of a defecatory disorder 1 It is essential to note that the American Gastroenterological Association's recommendations are based on the best available evidence, although the quality of evidence may be low or moderate 1. In real-life clinical practice, it is crucial to prioritize the patient's symptoms, medical history, and physical examination findings when deciding on the initial blood work and further evaluation.
From the Research
Initial Blood Work Recommendations
For a 75-year-old patient presenting with constipation, the initial blood work recommendations are not explicitly stated in the provided studies. However, some studies suggest that blood tests may be useful in identifying underlying causes of constipation, such as:
- Thyroid function tests, as hyperthyroidism or hypothyroidism can cause constipation 2
- Electrolyte levels, as imbalances can contribute to constipation
- Complete blood count (CBC), as anemia or other blood disorders can cause constipation
Relevant Studies
The following studies provide some guidance on the evaluation and management of constipation in elderly patients:
- A study published in 2020 recommends a stepwise approach to managing chronic constipation in elderly patients, including lifestyle advice, adjustment of chronic medications, and prescription of laxatives 3
- A study published in 2002 discusses the diagnosis and treatment of slow transit constipation, including the use of stimulant laxatives, polyethylene glycol, and misoprostol 4
- A study published in 2013 presents a case report of an elderly patient with primary colonic dysmotility, highlighting the importance of considering underlying pathology in the evaluation of constipation 5
Laboratory Reference Values
A study published in 2006 established reference intervals for 45 clinical chemistry analytes in apparently healthy 75-year-old subjects, which may be useful in interpreting laboratory results for elderly patients with constipation 6