Internal Medicine

0521779407-C04 CUNY1086/Karliner 0 521 77940 7 June 14, 2007 20:37

Cystic Fibrosis 453

■Exacerbations:

➣Insidious presentation most common, with increasing cough,

dyspnea, fatigue, anorexia and often weight loss

➣Acute presentations after viral infections

➣Fever usually low grade or absent

➣Musculoskeletal or pleural pain

Complications:

■Hemoptysis: may be life-threatening

■Pneumothorax

■Respiratory failure

■Hyperglycemia, hypoglycemia, almost never ketoacidosis

■Bowel obstruction

tests

Laboratory

■Basic tests:

➣Sweat chloride: <40 mEq/L=normal; 40–60 mEq/L suggestive,

>60 diagnostic

➣Hematology: leukocytosis, mild anemia common

➣ABG: for suspected ventilatory failure

➣Abdominal pain: amylase, liver functions

➣Diabetes: fasting blood glucose, hemoglobin A1C

➣Pancreatic insufficiency: protime, vitamin A and E

■Cultures:

➣Gram stain/culture for bacteria:S aureus,P aeruginosa,H

influenza, other gram-neg rods

➣Culture for mycobacteria, fungus

➣Blood cultures rarely helpful

■Spirometry:

➣Key to decision making (eg, when worse by 10–20%)

Imaging

■CXR: hyperinflation, bronchial wall thickening, scattered nodular

densities, cystic changes; upper lobe predominance; look for pneu-

mothorax, consolidation

■CT rarely helpful

differential diagnosis

■Sinusitis

■Bronchiectasis of other cause

■Pneumothorax