What is the recommended plan for a 60-year-old female (F) with a persistent dry cough for 6 weeks, following an upper respiratory illness (URI) with a sore throat, normal chest X-ray, and clear lungs, presenting with coughing fits and postnasal drip?

Differential Diagnosis for a 60-year-old female with a dry cough for 6 weeks

Single most likely diagnosis

• Postnasal drip syndrome: This is the most likely diagnosis given the presence of postnasal drip and a dry cough that started after a sore throat and upper respiratory illness. The normal chest X-ray and clear lungs also support this diagnosis, as postnasal drip syndrome is often associated with upper respiratory symptoms rather than pulmonary pathology.

Other Likely diagnoses

• Asthma: Although the lungs are clear, asthma can present with a dry cough, especially if it's an allergic or irritant-induced cough. The coughing fits could be consistent with asthma exacerbations.
• Gastroesophageal reflux disease (GERD): GERD can cause a dry cough, especially if stomach acid refluxes into the esophagus and then into the lungs, leading to irritation and coughing.
• Allergic rhinitis: Similar to postnasal drip syndrome, allergic rhinitis can cause a dry cough due to the constant irritation of the nasal passages and sinuses.

Do Not Miss (ddxs that may not be likely, but would be deadly if missed)

• Pulmonary embolism: Although the chest X-ray is normal and lungs are clear, a pulmonary embolism can sometimes present with a dry cough and no other symptoms. It's crucial to consider this diagnosis, especially in older adults.
• Lung cancer: A persistent dry cough in an older adult is always concerning for lung cancer, even with a normal chest X-ray. It's essential to consider this diagnosis and potentially order further imaging or refer to a specialist.
• Tuberculosis: Although less common, tuberculosis can present with a dry cough and no other symptoms. It's crucial to consider this diagnosis, especially if the patient has been exposed to someone with TB or has traveled to an area with high TB prevalence.

Rare diagnoses

• Sarcoidosis: This is a rare autoimmune disease that can cause a dry cough, among other symptoms. It's less likely, but could be considered if other diagnoses are ruled out.
• Eosinophilic pneumonia: This is a rare condition characterized by an accumulation of eosinophils in the lungs, which can cause a dry cough. It's less likely, but could be considered if other diagnoses are ruled out.

Recommended plan

The recommended plan would be to:

1. Order a chest CT scan to rule out any pulmonary pathology that may not be visible on the chest X-ray.
2. Perform pulmonary function tests (PFTs) to evaluate for asthma or other respiratory diseases.
3. Refer to an allergist to evaluate for allergic rhinitis or other allergic conditions.
4. Order a GERD evaluation, such as an upper endoscopy or ambulatory acid probe test, if GERD is suspected.
5. Consider a trial of postnasal drip syndrome treatment, such as antihistamines or decongestants, to see if symptoms improve.
6. Monitor the patient closely for any changes in symptoms or deterioration, and consider further testing or referral to a specialist if necessary.