Pathology Associates Of Lexington, P.A.
Pathology Associates Of Lexington, P.A.
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        Cough, Chronic, Causes
Cough Causes

A regular, spasmotic, coughing episode lasting off & on for 15-20 minutes can be a very dangerous thing, especially as a smokers' cough in women on hormone replacement. If such a patient also has an atrial septal defect (either as a defect or as a patent foramen ovale [PFO]), then small blood clots which are normally filtered out by the lung vessels can "ride" through that hole as the cough forces the right heart pressure higher than the left (a long macine-gun-like Valsalva maneuver occurs). That clot can cause a paradoxical embolic stroke of the brain or peripheral vascular infarcts causing odd pain patterns if not producing outwardly visible abnormalities.

It is not uncommon to have cough for complex (several combined reasons) reasons...meaning that it is not due just to one single cause. "In several studies of patients with chronic cough who were referred to pulmonologists: postnasal drip, asthma and/or GERD were found to be the cause of cough in 99 percent of immunocompetent nonsmokers who were not taking an ACE inhibitor (or beta blocker)...high blood pressure & cardiac drugs...and who had a normal or stable, near-normal chest radiograph. The methacholine inhalation challenge test (for asthma) was the most helpful test in making a diagnosis of asthma if the history was not suggestive. In 57 percent of patients diagnosed with asthma, the positive methacholine inhalation challenge was the only test indicative of the disease. In 23 percent of patients diagnosed with GERD, the prolonged esophageal pH monitoring test was the only indication of the disease. GERD is a recently recognized cause of chronic cough and is identified as the etiology of cough more frequently in studies that use prolonged esophageal pH monitoring as part of their diagnostic work-up. Sputum cytology may help if eosinophiles are identified (may indicate asthma or others, see chart below); lipid laden macrophages tend to reflect pulmonary aspiration of GERD material.

"In children, cough-variant asthma is the most common cause of chronic cough. However, in children younger than 18 months of age, congenital etiologies are an important cause. Chronic cough frequently has multiple causes. The authors of the studies cited in Table 1 found a single cause for cough in only 41 to 73 percent of patients, two causes in 23 to 42 percent of patients and three causes in 3 to 17 percent of patients (it is a "complicated" cough when more than one cause at same time). Many patients were correctly diagnosed by their primary physicians before being referred to a pulmonary specialist but had not been treated aggressively enough to stop the cough. The family physician is capable of directing the work-up, making the diagnosis and treating chronic cough in an estimated 90 percent of cases of chronic cough1." Cough causes can be mixed and not just a single cause, see above.

As a patient, you know what your habits are; but you may need to check your medications to see if any of them cause a chronic cough. There are two types of cough, (1) dry (non-productive) cough and (2) productive (sputum is produced) cough. A productive cough is more likely due to asthma, chronic irritant or allergic bronchitis, aspiration of gastric juices into the airways (post-stroke or GERD), and infections. Non-productive cough is more likely related to medications and non-lung causes. But some of the potentially fatal infectious "atypical pnuemonias" can be non-productive. Fever is a typical indicator of  infectious causes of cough...but "low grade" infections may not cause obvious fever. "Dry weather" or "winter cough" in normally moist geographic areas can complicate colds and other cough causes.

Some insight can be gained medically by looking at sputum coughed up from the lung (not snorted or coughed from the back of the throat or nose and not "spit" or saliva). Noticeable amounts of actual sputum are most likely available just after getting up from a night's sleep. Coughing the sputum into a white lavatory sink allows one to note slight color differences that are important. And, that same sputum can be used for bacterial or fungal cultures or for microscopic exam by smear or cell block. Put it into a cup or container and take to your doctor or the lab.

Acute bronchitis is when the process lasts 3 weeks or less. True chronic bronchitis is a cough that lasts at least 3 months per year for at least 2 consecutive years; and when more frequent or sustained, it is called ACEB (acute exacerbation of chronic bronchitis) and often in those with COPD (chronic obstructive pulmonary disease).

Common causes of chronic cough:
Disorder Clinical Sputum Character Sputum Micro
20% of acute bronchitis cases go well beyond 3 weeks look out for whooping cough, especially if paroxysmal cough (hear it here); also Strep., Moraxella, & Haemophilus; and "atypical pneumonia" organisms sticky grey to yellowish polys
smoking     white with faint brownish areas pigment macrophages
environmental irritants   usually not sputum producer  
dry environment cough (especially seasonal dryness in a usually-moist environment) by itself, non-productive (often enhanced by irritants & allergens) usually not sputum producer n/a
allergens (broncho-pulmonary allergic reaction): chronic allergic naso-tracheo-bronchitis itching inner corners of eyes; copious, clear nasal discharge; cough which is sometimes spasmodic clear or with faint greyish tint sometimes...NOT obviously yellow eosinophiles
postnasal drip (PND) due to nasal congestion (alpha blockers like Flomax can do it)   usually not sputum producer no particular cells
asthma (see VCD, below)   sputum producer eosinophiles
GERD   clear-whitish, mucoid no eos. & no polys unless complicated by allergy or infection; lipid laden macrophages
chronic bronchitis see causes below as below  
COPD   usually sputum producer polys
mixed causes   sputum thick & sticky [S08-3396]  
AECB3 (acute exacerbation of chronic bronchitis) chest X-ray no different than chronic bronchitis & this helps distinguish AECB from pneumonia. These features:
  • cough
  • dyspnea
  • productive
  • purulent
  • RR >25/min.
  • decreased FEV
  • constitutional symptoms/signs

as per causes  
transient (say, after virus infection) airway hyper-responsiveness   usually not sputum producer not eosinophiles
meds: ACE inhibitors & beta blockers dry bronchospastic; worse @ night not sputum producer  
Less common causes of chronic cough:
Disorder Clinical Sputum Character Sputum Micro
congestive heart failure   usually not sputum producer  
vocal cord dysfunction (VCD) asthma like & can overlap with asthma non-productive cough n/a
endotracheal growths   usually not sputum producer  
esophagus  or lung ca.   usually not sputum producer  
interstitial lung diseased &/or COPD   usually not sputum producer  
bronchiectasis (with or without PCD...primary ciliary dyskinesia)   yellow purulent polys
chronic infections (TB & Fungal)   yellowish or contains whitish particles polys; eosinophiles if producing allergic, asthma like complications
recurrent aspiration (post-stroke; druggie; alcoholic; bad or neglected GERD)   usually a sputum producer  
mediastinal mass   usually not sputum producer  
irritation of cough receptors in external ear canal   not sputum producer  
occupational irritant inhalation   usually not sputum producer  
foreign body   likely a sputum producer  
as a reflex to premature atrial beats or PVCs   not sputum producer n/a
nervous habit (learned behavior) especially preteens & teens not a sputum producer  
psychogenic   not sputum producer  
Carrington's chronic eosinophilic pneumonia elevated CBC eos usually not much of a sputum producer eosinophiles
Check for their diagnosis decision chart.
Acute (lasting less than 3 weeks) Cough:
  Clinical Sputum Sputum Micro
acute bacterial bronchitis in healthy people 5-10% of acute cases & due to mycoplasmas, chlamydias, and B. pertussis (whooping cough [famous for inspiratory whoop & post coughing vomiting]...20% with cough greater than 2 weeks have this3). Test methods...PCR vs. culture & other...have large variability in results4. yellowish sputum polys
acute bacterial bronchitis in people who have broncial (even just smokers or GERD injury) or lung disease or just had viral bronchitis any of the above 3; or, also, Strep. pneumoniae, Hem. influenzae, & Moraxella catarrhalis. yellowish sputum polys
acute viral bronchitis 90% of acute cases mild amount of sputum polys
acute allergic bronchitis   sputum producer eosinophiles
acute asthmatic bronchitis   sputum producer eosinophiles
pulmonary emboli in increased risk of clotting (thrombophilia) situations not sputum producer n/a


  1. An Office Approach to the Diagnosis of Chronic Cough, W. Ross Lawler
    American Family Physician, Dec. 1998.By way of search engine in "Find Articles".
  2. Chronic Cough, ELIZABETH B. PHILP, M.B., CH.B., University of Alabama School of Medicine, Tuscaloosa, Alabama, American Family Physician, Oct.1, 1997.
  3. Lipsky M, Le J, Therapeutic Management of Bronchitis, Preventive Medicine ion Managed Care 5(1 sup):1-8, February 2005.
  4. Sept. 26 JAMA MMWR from CDC about pertussis test variations HERE.
(posted 2002; latest adjustment 17 April 2015)
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