A 15 year old boy with cystic fibrosis presents with a 3-6kg weight loss over the past month unaccompanied by changes in his pulmonary and gastrointestinal symptoms. You suspect that he has developed which of the following?
**Core Concept**
Cystic fibrosis is a genetic disorder characterized by abnormal chloride transport in the epithelial cells, leading to thickened secretions in various organs, including the lungs and pancreas. The condition often results in malnutrition and growth retardation due to pancreatic insufficiency and malabsorption.
**Why the Correct Answer is Right**
The patient's weight loss, despite stable pulmonary and gastrointestinal symptoms, suggests the development of a new complication. In cystic fibrosis, the accumulation of fat-soluble vitamins, particularly vitamin D and vitamin K, is common due to malabsorption. This can lead to osteoporosis and increased risk of fractures. Moreover, the deficiency of vitamin K can cause an increase in the levels of prothrombin time and INR. However, the most likely complication is the development of **osteoporosis**.
**Why Each Wrong Option is Incorrect**
**Option A:** The patient's presentation does not match the typical symptoms of cystic fibrosis-related diabetes (CFRD), which includes polyuria, polydipsia, and weight gain.
**Option B:** While cystic fibrosis-related diabetes (CFRD) is a common complication, the patient's presentation is more suggestive of a different complication.
**Option C:** Cystic fibrosis-related liver disease is a complication but not typically associated with weight loss without accompanying liver dysfunction.
**Clinical Pearl / High-Yield Fact**
In cystic fibrosis, patients with a body mass index (BMI) below 18.5 have a higher risk of developing complications, including osteoporosis, and should be closely monitored for these conditions.
**Correct Answer:** C.