Cystic fibrosis

Definition

An autosomal recessive inherited illness. It basically makes all the exocrine glands screw up, thus causing problems in the lungs, liver, pancreas and intestines.

Epidemiology

In white Europeans its about 1 in 2,500 births. For some reason, the less that description matches you, the rarer CF is. So in black Africans, its 1 in 10,000, and native Asians, more like 1 in 25,000.

Pathophysiology

Its complex. Simple version; the ion transporters in the exocrine cells don't work properly. This means the excretions end up super concentrated, becoming thick and gooey. As you might suspect, this might have some impact on various body organs:

• The lungs fill with goo - this makes them much better at picking up infections, and much less good at getting rid of them. Many CF sufferers end up with a chronic Pseudomonas infection, and frequently get pneumonia.
• The pancreas fills with goo - this blocks it up, and prevents enzymes from passing into the digestive tract, leading to malnutrition. It also blocks insulin passing through, and the built up enzymes attack the Islets of Langerhans, causing diabetes and pancreatitis.
• The liver fills with goo - the jury is out on exactly what this does, but liver failure is the second highest cause of death in CF sufferers. They often develop cirrhosis, and that's bad.
• The intestines fill with goo - and this can present as meconium ileus, where the first batch of a baby's poo gets stuck in the ileum as it mixes with the extra mucus. In 20% of CF sufferers, they will diagnosed soon after birth due to this happening.
• Infertility is very common - women get filled with goo which screws up the ovaries, and men get a congenital absense of the vas deferens

Risk Factors

Since this is an inherited condition, the only risk is family history, and specifically; if both of your parents are carriers of the CFTR gene, then you will get it. Parents can thus screen themselves before pregnancy to see if there is a risk for their children.

Clinical Features

clubbing

Investigations

For diagnostics, they use the sweat test - as it comes from an exocrine gland, the sweat is mega concentrated in sodium and other ions, and this shows up in testing.