How is CF Diagnosed and Treated?

How is CF diagnosed?

Newborn screening - As of 2010 all states screen newborns for cystic fibrosis.  The first step is a blood test that is done a couple of days after birth. This sample is sent to a lab to screen for multiple disorders.  The screening test for CF looks for elevated levels in an immunoreactive trypsinogen (IRT), which is an enzyme created by the pancreas.  If the IRT levels are high then the screening for CF is positive.  This doesn't mean that the child has CF, because there are other disorders that can cause this.  So in most states the blood is then sent for a DNA test.  The DNA test shows whether a newborn has faulty CFTR genes.  There are over 1,200 known mutations that cause CF so only the common ones are tested.  If the levels were elevated and no mutation was found, the results are sent to the primary physician to determine if furthur tests are necessary.  If a mutation is found then the child is either a carrier or has CF and the final test is done called the sweat test.

Sweat test - When the IRT, DNA or both tests suggest cystic fibrosis, a doctor will confirm the diagnosis with a sweat test.  This test measures the amount of salt in the sweat and is the most useful test for diagnosing cystic fibrosis.  The doctors trigger sweating on a small patch of skin on an arm or leg.  They rub the skin with a sweat-producing chemical and then use an electrode to provide a mild electrical current.  This may cause a tingling or warm feeling.  Sweat is collected on a pad or paper and then analyzed.  The sweat test usually is done twice.  High salt levels confirm a diagnosis of cystic fibrosis.

Treatments

The main treatments for people with CF are chest airway clearance, medicines and exercise.  Exercise is good for CF patients because it causes deep breathing and helps move the mucus through the airway.

Airway Clearance Techniques (ACT's) -  These techniques are used to move mucus from the small airways to the larger ones to be coughed or huffed out.  This is very important for people with CF because it helps move the sticky mucus out of the lungs.  If mucus is not moved out of the airways, it remains in the lungs causing blockages and infections.

Coughing is a reflex.  It clears mucus with high-speed airflow, but sometimes mucus cannot be cleared just with just coughing.

Huffing is a type of cough.  It also involves taking a breath in and actively exhaling.  It is more like "huffing" onto a mirror or window to steam it up.  It is not as forceful as a cough but can work better and be less tiring.

Chest Physical Therapy (CPT or Chest PT) or Postural Drainage & Percussion (PD&P).  This is an ACT that often includes postural drainage and chest percussion.  Postural drainage is accomplished when the person gets in varied positions (postures) that drain mucus from different parts of the lung.  Gravity pulls mucus from small to large airways where it can be coughed up.  Chest percussion is accomplished by clapping on the chest and back with cupped hands in order to dislodge and move mucus.  This is done in varied positions to drain all sections of the lung.

Oscillating Positive Expiratory Pressure (Oscillating PEP) is an ACT where the person blows all the way out many times through a device.  Types of Oscillating PEP devices include the Flutter, Acapella, Cornet

and Intrapulmonary Percussive Ventilation (IPV).  Breathing with these devices vibrates the large and small airways.  This vibration thins, dislodges and moves mucus.  After blowing through the device many times, the person coughs or huffs.  This cycle is repeated many times.






High-frequency Chest Wall Oscillation also is called the Vest.  An inflatable vest is attached to a machine that fills up the vest and vibrates it at a high frequency.  The vest vibrates the chest to loosen and thin mucus.  Every ten minutes the person stops the machine and coughs or huffs.





Medications and supplements include:
Anti inflammatory medicines to help with inflammation in the lungs:  Ibuprofen, Azithromycin
Bronchodilator meds:  Albuterol, Advair
Mucus alteration meds:  Pulmozyme (thins mucus)
Airway Surface Liquid:  Hypertonic saline (inhaled salt)
Oral antibiotics:  Cipro, Levoquin                                                                                                           Inhaled antibiotics:  TOBI, Cayston, Colistin
IV antibiotics:  Tobramycin, Ceftazidime, Zosyn (Pipercacillin-tazobactam), Colistin
Enzymes for digestion:  Creon, Zenpep
High Calorie supplements:  Boost, Ensure
Vitamin supplements
Insulin for CFRD

Not all CF patients use all of these medications.  Some patients may only need a few of these while others need more.  There are many medications used that I have not listed here.  These are just examples of some medications that are used.

Potentiators and Correctors:  All of the previous treatments help with the symptoms. There is now research being done in order to fix the under lying cause. The correctors are drugs that work on getting the protein channel into the membrane.  Potentiators help with the gating of the protein that is already in the membrane so it can transport Cl-.

An example of a potentiator is Kalydeco.  This is the first and only (at this point) FDA approved CFTR potentiator.  This drug works for people with the mutation G551D*.  This mutation is found in about 4-5% of cystic fibrosis cases.  With this mutation the CFTR protein makes it to the epithelial cell surface, but it does not transport chloride through the channel.  This drug improves the transport and is showing great success.

*G551D is a standard amino acid abbreviation for a mutation in which the amino acid glycine (G) in position 551 is replaced with aspartic acid (D).