Repeated USMLE Questions Step 2 CK- 438

A 9-month-old boy is brought to the pediatrician for persistent cough, poor weight gain, and several bouts of pneumonitis. Upon taking history from his mother, she mentions that her boy had been also having foul-smelling and very large stools for a few months.

Which of the following diagnostic techniques will help to provide the correct diagnosis of this condition?

A- TB skin test

B- CT of the chest

C- Serum immunoglobulins

D- Sweat chloride test


Keeping the symptoms of the baby in mind, this is most likely a case of cystic fibrosis, which generally presents during infancy with poor growth and recurrent respiratory and/or intestinal disorders. The sweat chloride test is one of the most common diagnostic tests used to evaluate a patient if you suspect cystic fibrosis. Cystic fibrosis impacts the manner in which chloride moves in and out of cells. As sweat contains chloride in the form of sodium chloride, sweat chloride test is used as the standard method for diagnosing cystic fibrosis.

The correct answer is D

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