Is 1 Liter of Nasal Fluid Produced a Day Truly Normal?
The vast majority of references found on simple google searching are quotes from ENT's interviewed for a magazine or newspaper article.
On deeper searching, 1 liter of normal nasal drainage can be found mentioned in research articles or medical texts, but still no explanation on how this volume was determined.
• "Approximately 1 liter of fluid is produced by nasal epithelium each day." [Medical Textbook, page 120]
• "A rough calculation of the daily volume of secretion and transudate from the nose is 1000 cc." [Research paper, page 126]
• "Mucociliary clearance is defined as cleaning of upper and lower airway by interaction of nasal mucus (about 200 g or 2 litre/day produced by the respiratory mucosa)" [Research paper, reference #36]
• I was able to find actual research describing methods to determine nasal secretion volume in animal studies. Here's one on guinea pigs.
• Using similar methods in animals, here's a research paper that described inserting filter paper into the nasal cavity of people and weighing how much secretions were absorbed after a period of time, but such information may not be entirely accurate due to nasal irritation from the filter paper itself.
• Here's another research paper describing a method of measuring nasal fluid by the urea concentration present.
Why is this Important?
One of the most common complaints people have when seeing a doctor is post-nasal drip or post-nasal drainage.
Typically such an abnormal sensation is NOT attributable to actual increase in nasal fluid volume, but rather changes in consistency and/or protein concentration along with environmental factors related to humidity and temperature.
However, if the underlying facts related to normal nasal fluid volume is incorrect, it does bring into question whether current treatment strategies is not ideal or at worst, frankly inaccurate.
Thus far, I have been stumped regarding where exactly the claim that a normal human nose produces 1 liter of fluid.
If any reader can shed light on this claim, that would be wonderful! Please report your findings below under the comment section.
Ideally, the information I am most interested in is the original source reference as well as the methodology used to determine the nasal fluid volume.
Nasal anatomy, physiology, and function. J ALLERGY CLIN IMMUNOL 72:123-128, 1983
Bacteriology of Humans: An Ecological Perspective. By Michael Wilson. John Wiley & Sons, Jan 26, 2009 - Science - 360 pages
A new method of the measurement of nasal secretion in guinea pigs. Int Arch Allergy Appl Immunol. 1991;95(1):29-34.
The Source of Nasal Secretion in the Normal Condition: Fluorescein Tests. Acta Oto-Larnyngologica. 1949;37:446-50.
Physiology and pathophysiology of respiratory mucosa of the nose and the paranasal sinuses. GMS Curr Top Otorhinolaryngol Head Neck Surg. 2010; 9: Doc07. Published online 2011 Apr 27. doi: 10.3205/cto000071
A standardized filter paper technique for assessing nasal secretory activity. Clinical Allergy, 1981, Volume 11, pages 287-292
Estimation of nasal epithelial lining fluid using urea as a marker. J ALLERGY CLIN IMWJNOL 1993;92:457-65.)
Allergologie-Handbuch: Grundlagen und klinische Praxis. Stuttgart: Schattauer; 2006.