Poor uptake of vitamin D from the diet because of malabsorption can lead to the bone disease osteoporosis in which weakened bones are more susceptible to fractures. Infertility
Infertility affects both men and women. At least 97% of men with cystic fibrosis are infertile, but not sterile, and can have children with assisted reproductive techniques. The main cause of infertility in men with CF is congenital absence of the vas deferens (which normally connects the testes to the ejaculatory ducts of the penis), but potentially also by other mechanisms such as causing no sperm, abnormally shaped sperm, and few sperm with poor motility. Many men found to have congenital absence of the vas deferens during evaluation for infertility have a mild, previously undiagnosed form of CF. Around 20% of women with CF have fertility difficulties due to thickened cervical mucus or malnutrition. In severe cases, malnutrition disrupts ovulation and causes a lack of menstruation. Causes
CF is caused by a mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR). The most common mutation, ΔF508, is a deletion (Δ signifying deletion) of three nucleotides that results in a loss of the amino acid phenylalanine (F) at the 508th position on the protein. This mutation accounts for two-thirds (66–70%) of CF cases worldwide and 90% of cases in the United States; however, over 1500 other mutations can produce CF. Although most people have two working copies (alleles) of the CFTR gene, only one is needed to prevent cystic fibrosis.
Nutrient supplementation
It is uncertain whether vitamin A or beta-carotene supplementation have any effect on eye and skin problems caused by vitamin A deficiency.There is no strong evidence that people with cystic fibrosis can prevent osteoporosis by increasing their intake of vitamin D.For people with vitamin E deficiency and cystic fibrosis, there is evidence that vitamin E supplementation may improve vitamin E levels, although it is still uncertain what effect supplementation has on vitamin E‐specific deficiency disorders or on lung function.Robust evidence regarding the effects of vitamin K supplementation in people with cystic fibrosis is lacking as of 2020.Various studies have examined the effects of omega-3 fatty acid supplementation for people with cystic fibrosis but the evidence is uncertain whether it has any benefits or adverse effects. Procedures
Several mechanical techniques are used to dislodge sputum and encourage its expectoration. One technique good for short-term airway clearance is chest physiotherapy where a respiratory therapist percusses an individuals chest by hand several times a day, to loosen up secretions. This "percussive effect" can be administered also through specific devices that use chest wall oscillation or intrapulmonary percussive ventilator. Other methods such as biphasic cuirass ventilation, and associated clearance mode available in such devices, integrate a cough assistance phase, as well as a vibration phase for dislodging secretions. These are portable and adapted for home use.Another technique is positive expiratory pressure physiotherapy that consists of providing a back pressure to the airways during expiration.