Cystic Fibrosis

Question

My daughter has an elevated sweat test value. 60-80 would be normal. She is at 75.

The test was done due to an anal prolapse, and she is also small in stature. The test will be repeated in February. I am all run down. The doctor says there are 1200 sub-groups and the disease will not necessarily appear. And who could it come from, since it is hereditary.

Answer

Hello,
CF is a hereditary disease with a dysfunction or absense of a chloride channel, which is located in the membrane of the cell and causes a thickening of secretions produced by the affected cell. The main organs which are involved are the lung and the pancreas. Due to a lack of secreted pancreatic enzymes, the food can not be digested fully anymore, leading to problems such as fatty, voluminous stools, intestinal obstruction and lacking weight gain of the patient. An anal prolapse can also be a symptom.
The genetic material in humans consists of pairs of chromosomes, that means every gene location is there in duplicate. A patient is only suffering from CF if both of his genes coding for the chloride channel, are affected; so if a child is born with the illness of CF, it has become one affected gene from each parent. As only two affected genes lead to the illness, the parents are healthy as each parent carries a normal and an affected gene.
Anal prolapse develops in CF patients in case of pancreatic hypofunction. It is also found with long-lasting congestion even in otherwise healthy children. Therefore, one should check your daughter's stool for Elastase I. If that test shows the pancreatic function to be normal, then CF would be rather unlikely.

If there is a suspicion, a sweat test is performed which is considered to be pathologic if the chloride value is above 60 mmol/l. However, it is important to have this test performed in a center which much experience in performing the test in order to get reliable results. A first pathologic test should always be affirmed with a second sweat test, other diagnostic tools may be helpful such as a genetic analysis, especially in borderline cases.

Generally, you should not accept the fact that the test will be repeated only in February. Understandably, you are very concerned about the suspicion that was voiced. Therefore, this needs to be clarified as soon as possible. The sweat test should be repeated at a certified CF center close-by. Should that not be sufficient for clarification, the doctors at the center will discuss the further diagnostic procedure.
Kind regards,
Dr. H.-G. Posselt

05.01.2009