The studies and clinical information you cite suggests that the source of the productive cough is your daughter’s lungs and not from an upper respiratory site. If that is the case, then she appears to have some type of chronic lung disease, assuming that GERD with recurrent aspiration has been completely ruled out. In this regard, a clinically negative response to 3 weeks of Protonix does not rule out the diagnosis of GERD and her doctors might want to consider further test to definitively rule out that diagnosis.
If the cough and sputum are a reflection of intrinsic lung disease, not secondary to GERD or to any other cause of recurrent aspiration, for example laryngeal dysfunction, then the next step would be to determine the underlying lung disorder. Bronchiectasis can develop with or without CF and is not rare. You should confirm with the pulmonologist that the negative testing for CF was comprehensive enough to, for all practical purposes, effectively rule out the diagnosis of CF. See the highlighted area in the following abstract from a recent (2007) report on extended CF mutation testing.
Other, rather uncommon, causes of the chronic productive cough would include Alpha-1 anti-trypsin deficiency, a condition called ABPM that can occur with asthma, and infection with an unusual bacterium, such as Non-tuberculous Mycobacteria. Your daughter’s pulmonary specialist is acting responsibly in taking the risk of radiation exposure from CT scanning into account. From here on that risk, one that can reasonably be quantified, should be weighed against the effect of this chronic illness on her lungs and, maybe, on her quality of life. And, should the problem prove to be localized in one lung, the potential (and risks) of curative surgery.
One more thought. The 12 month hiatus, during which she was free of cough and sputum might be seen as evidence that favors infection or GERD rather than an intrinsic lung disease.
Good luck,
Authors Full Name: Lebo, Roger V. Omlor, Greg J.
Institution: Department of Pathology, Akron Children's Hospital, Akron, OH 44308-1062, USA. ***@****
Title: Targeted extended cystic fibrosis mutation testing on known and at-risk patients and relatives.
Source: Genetic Testing. 11(4):427-44, 2007.
Abstract: This paper reports mathematically derived residual risks of being a carrier or being affected with cystic fibrosis following various screening scenarios to assist in interpreting test results and advising patients. While parental screening with 23 American College of Medical Genetics (ACMG) cystic fibrosis mutations defines the 64% of affected U.S. Caucasian fetuses with two detectable mutations, newborn screening for elevated immunoreactive trypsinogen (IRT) and sweat chloride identifies an additional 36% of affected newborns with zero or one detected mutation. The relatives of these affected newborns with less than two detectable mutations have higher posterior (after) 23 mutation-negative test risks of carrying undetected mutations. These calculations emphasize how knowledge of the mutations in the related affected patient substantially improves upon the quality of after-test advice to patients. Furthermore, negative tests of the partner without a family history and/or more extensive cystic fibrosis transmembrane conductance regulator (CFTR) gene testing also increases the likelihood that a negative report is truly negative. When a newborn patient with zero or one detected CFTR mutation has an inconclusive sweat test result, the sweat test should be repeated before ordering additional often unnecessary CFTR gene sequencing. Given the same composite mutation panel test