Crohns Disease

Everything you need to know about Crohns Disease - symptoms, causes, treatment options available in Australia, and when to see a doctor. Evidence-based medical information.

Dr. Louis J Sisk

BSc(Hons) MBChB MRCS(Glasg) MTrauma

Published: August 23, 2025

Overview

Crohn’s Disease (CD) is a chronic inflammatory condition of the gastrointestinal tract, characterised by its relapsing and remitting nature. It is a type of Inflammatory Bowel Disease (IBD), which also includes ulcerative colitis. The pathophysiology of Crohn’s Disease involves a complex interplay of genetic, environmental, and immunological factors. The disease is marked by transmural inflammation, which can affect any part of the gastrointestinal tract from mouth to anus, but most commonly impacts the terminal ileum and colon. Inflammation in Crohn’s Disease is discontinuous, often described as "skip lesions", and can lead to complications such as strictures, fistulas, and abscesses [1][2].

The underlying mechanisms involve an inappropriate immune response to intestinal microbiota in genetically susceptible individuals. Key cellular and molecular pathways include the dysregulation of T-helper cells, particularly Th1 and Th17, and the production of pro-inflammatory cytokines such as TNF-alpha, IL-12, and IL-23. These processes contribute to the chronic inflammation and tissue damage seen in Crohn’s Disease [3][4].

Statistics and Prevalence in Australia

In Australia, the prevalence of Crohn’s Disease is approximately 653 per 100,000 people, based on 2019 data. The broader category of IBD is projected to affect about 1% of the Australian population by 2030 [1][3][5]. The disease burden is notably higher among females, adults, and urban populations. As of recent estimates, around 180,000 Australians are living with IBD, highlighting the significant public health impact of this condition [2][4].

Symptoms and Clinical Presentation

The clinical presentation of Crohn’s Disease can vary widely, depending on the location and severity of inflammation. Common symptoms include abdominal pain, diarrhoea, weight loss, and fatigue. Early signs may be subtle, such as mild abdominal discomfort or changes in bowel habits. As the disease progresses, symptoms can become more severe and include bloody stools, fever, and malnutrition due to malabsorption [1][2].

Red flag symptoms that require immediate medical attention include severe abdominal pain, persistent vomiting, significant weight loss, and signs of intestinal obstruction or perforation. Atypical presentations can occur, particularly in children and the elderly, where growth retardation or unexplained anaemia may be the initial indicators [3][5].

Causes and Risk Factors

The exact cause of Crohn’s Disease remains unknown, but it is believed to result from a combination of genetic predisposition, environmental factors, and an abnormal immune response. Genetic factors play a significant role, with several susceptibility genes identified, including NOD2/CARD15, which are involved in the immune response to bacterial components [3][4].

Environmental factors such as smoking, diet, and stress have been implicated in the disease’s onset and exacerbation. Smoking is a well-established risk factor, associated with increased disease severity and complications. Additionally, a Western diet high in processed foods and low in fibre may contribute to the development of Crohn’s Disease [1][2].

Diagnosis

The diagnosis of Crohn’s Disease in Australia follows a comprehensive approach, incorporating clinical evaluation, laboratory tests, and imaging studies. The Royal Australian College of General Practitioners (RACGP) and the National Health and Medical Research Council (NHMRC) provide guidelines for the diagnostic process [6][8].

Initial assessment includes a detailed medical history and physical examination, supported by blood tests to check for inflammatory markers, anaemia, and nutritional deficiencies. Stool tests, particularly faecal calprotectin, are useful for detecting intestinal inflammation [2][6].

Endoscopy with biopsy remains the gold standard for diagnosis, allowing direct visualisation of the gastrointestinal tract and histological confirmation of inflammation. Imaging studies such as MRI or CT enterography are valuable for assessing the extent of disease and identifying complications like strictures or fistulas [7][9].

Treatment Options in Australia

The management of Crohn’s Disease involves a combination of pharmacological and non-pharmacological strategies, tailored to the individual’s disease severity and location. Treatment aims to induce and maintain remission, prevent complications, and improve quality of life [6][7].

First-line pharmacological treatments include aminosalicylates, corticosteroids, and immunomodulators such as azathioprine and methotrexate. Biologic therapies, including anti-TNF agents (e.g., infliximab, adalimumab) and newer agents targeting IL-12/23 pathways, are reserved for moderate to severe cases or those refractory to conventional treatments [6][8].

Non-pharmacological strategies encompass dietary modifications, smoking cessation, and stress management. Surgical intervention may be necessary for complications such as strictures, fistulas, or abscesses, with the goal of preserving as much bowel as possible [1][2].

In Australia, treatment access is supported by the Pharmaceutical Benefits Scheme (PBS), which subsidises many medications used in the management of Crohn’s Disease. Medicare also provides coverage for necessary diagnostic and therapeutic procedures [5][6].

Living with Crohns Disease

Living with Crohn’s Disease requires ongoing management and support. Regular monitoring and follow-up with healthcare providers are essential to assess disease activity, adjust treatment plans, and address any complications [3][4].

Patient education is a cornerstone of management, empowering individuals to recognise symptoms, adhere to treatment regimens, and make informed lifestyle choices. Self-management strategies, including dietary adjustments and stress reduction techniques, can significantly impact disease control and quality of life [1][2].

Psychosocial support, including counselling and support groups, can help address the emotional and mental health challenges associated with chronic illness. Care coordination is particularly important for individuals with complex disease, ensuring seamless communication between gastroenterologists, general practitioners, and other specialists [5][9].

Prevention

While there is no known way to prevent Crohn’s Disease entirely, certain strategies may reduce the risk of flare-ups and complications. Smoking cessation is strongly advised, as smoking is a modifiable risk factor that exacerbates disease severity [1][2].

Dietary modifications, such as increasing fibre intake and reducing processed foods, may help maintain remission and improve gut health. Stress management techniques, including mindfulness and relaxation exercises, can also play a role in preventing disease exacerbations [3][4].